PATENT DOCUMENT

Publication Number: US-9591181-B2
Application Number: US-201213629305-A
Country: US
Kind Code: B2

Title: Sharing images from image viewing and editing application

Abstract:
Some embodiments provide an image-editing application. The image-editing application uploads an image to a remote image hosting website. From the image hosting website, the application receives data that identifies the image on the remote image hosting website. The application uses the received data to identify when a user of the remote image hosting website has commented on the image. The application displays the user comments from the remote image hosting website in the image-editing application.

Claims:
I claim: 
     
       1. A machine readable medium of a client device, the machine readable medium storing an image-editing application executable by at least one processing unit of the client device, the image-editing application comprising sets of instructions for:
 performing a set of image editing operations on an image with a set of tools of the image-editing application; 
 uploading the edited image to a remote third-party image hosting website from the image-editing application; and 
 while the edited image is displayed in a display area of a graphical user interface (GUI) of the image-editing application:
 retrieving a comment stream associated with the edited image from the remote third-party image hosting website, the comment stream comprising user comments; 
 displaying the user comments from the remote third-party image hosting website in a comment display area of the GUI of the image-editing application; 
 receiving additional comments through input to the comments display area via the GUI of the image-editing application; and 
 sending the received additional comments to the remote third-party image hosting website to associate the received additional comments with the edited image. 
 
 
     
     
       2. The machine readable medium of  claim 1 , wherein the image-editing application further comprises a set of instructions for displaying a notification that new comments are available. 
     
     
       3. The machine readable medium of  claim 2 , wherein the notification is displayed as a number that indicates a number of new comments since the last time the image-editing application accessed the comments for the edited image. 
     
     
       4. The machine readable medium of  claim 2 , wherein the notification is displayed over a selectable item for viewing the comments within the image-editing application. 
     
     
       5. The machine readable medium of  claim 1 , wherein the set of instructions for uploading the edited image comprises a set of instructions for uploading a caption for the edited image to the remote third-party image hosting website. 
     
     
       6. The machine readable medium of  claim 5 , wherein the image-editing application further comprises a set of instructions for receiving the caption as user input through the GUI of the image-editing application. 
     
     
       7. The machine readable medium of  claim 6 , wherein the user input comprises touchscreen input through a touchscreen keyboard. 
     
     
       8. The machine readable medium of  claim 1 , wherein the image-editing application further comprises a set of instructions for receiving, from the remote third-party image hosting website, an image identifier that identifies the edited image on the remote third-party image hosting website. 
     
     
       9. The machine readable medium of  claim 8 , wherein the set of instructions for retrieving the comment stream comprises sets of instructions for:
 sending the received image identifier to the remote third-party image hosting website as a request for the comment stream; 
 receiving the comment stream; and 
 determining whether any comments in the comment stream are new comments in order to identify whether a user of the remote third-party image hosting web site has commented on the edited image. 
 
     
     
       10. The machine readable medium of  claim 9 , wherein the comment stream comprises a timestamp for each comment in the comment stream, wherein the set of instructions for determining whether any comments in the comment stream are new comments comprises a set of instructions for comparing the timestamp of a most recent comment to a timestamp of the last time the application accessed the comments for the edited image. 
     
     
       11. For a client device, a method for sharing an image through an image-viewing application of the client device, the method comprising:
 uploading an image to a remote third-party image hosting website; 
 in response to receiving a request to display the image, retrieving a comment stream from the remote third-party image hosting website, the comment stream comprising user comments about the image; 
 displaying the image in a first display area of a graphical user interface (GUI) of the image-viewing application and the user comments from the remote third-party image hosting website in a comments display area of the GUI of the image-viewing application; 
 receiving additional comments through input to the comments display area via the GUI of the image-viewing application; and 
 sending the received additional comments to the remote third-party image hosting website to associate the received additional comments with the image. 
 
     
     
       12. The method of  claim 11  further comprising receiving, from the remote third-party image hosting website, an image identifier that identifies the image, wherein retrieving the comment stream comprises:
 sending the received image identifier to the remote third-party image hosting website as a request for the comment stream; 
 receiving the comment stream; and 
 determining whether any comments in the comment stream are new comments in order to identify whether any user of the remote third-party image hosting website has commented on the image. 
 
     
     
       13. The method of  claim 12 , wherein the comment stream comprises a timestamp for each comment in the comment stream, wherein determining whether any comments in the comment stream are new comments comprises comparing the timestamp of a most recent comment to a timestamp of the last time the image-viewing application accessed the comments for the image. 
     
     
       14. The method of  claim 11  further comprising displaying a notification that new comments are available. 
     
     
       15. The method of  claim 14 , wherein the notification is displayed as a number that indicates a number of new comments since the last time the image-viewing application accessed the comments for the image. 
     
     
       16. The method of  claim 14 , wherein the notification is displayed over a selectable item for viewing the comments within the image-viewing application. 
     
     
       17. The method of  claim 11 , wherein uploading the image comprises uploading a caption for the image to the remote third-party image hosting website. 
     
     
       18. The method of  claim 11 , wherein the method further comprises receiving the caption as user input through the GUI of the image-viewing application. 
     
     
       19. The method of  claim 18 , wherein the user input comprises touchscreen input through a touchscreen keyboard. 
     
     
       20. A client device comprising:
 a set of processing units; and 
 a machine readable medium storing an image-editing application executable by at least one of the processing units of the client device, the image-editing application comprising sets of instructions for:
 uploading an image to a remote third-party image hosting website; and 
 while the image is displayed in a display area of a graphical user interface (GUI) of the image-editing application:
 identifying when a user of the remote third-party image hosting website has commented on the image; 
 displaying the user comments from the remote third-party image hosting website in a comments display area of the graphical user interface (GUI) of the image-editing application; 
 receiving additional comments through input to the comments display area via the GUI of the image-editing application; and 
 sending the received additional comments to the remote third-party image hosting website to associate the received additional comments with the image. 
 
 
 
     
     
       21. The client device of  claim 20 , wherein the image-editing application further comprises a set of instructions for displaying a notification that new comments are available. 
     
     
       22. The client device of  claim 21 , wherein the notification is displayed as a number that indicates a number of new comments since the last time the application accessed the comments for the image. 
     
     
       23. The client device of  claim 21 , wherein the notification is displayed over a selectable item for viewing the comments within the image-editing application. 
     
     
       24. The client device of  claim 20 , wherein the image-editing application further comprises a set of instructions for receiving, from the remote third-party image hosting website, an image identifier that identifies the image on the remote third-party image hosting web site. 
     
     
       25. The client device of  claim 24 , wherein the set of instructions for identifying comprises sets of instructions for:
 sending the received image identifier to the remote third-party image hosting website as a request for a comment stream comprising user comments; 
 receiving the comment stream; and 
 determining whether any comments in the comment stream are new comments. 
 
     
     
       26. The client device of  claim 25 , wherein the comment stream comprises a timestamp for each comment in the comment stream, wherein the set of instructions for determining whether any comments in the comment stream are new comments comprises sets of instructions for comparing the timestamp of a most recent comment to a timestamp of the last time the application accessed the comments for the image. 
     
     
       27. The client device of  claim 20 , wherein the image-editing application further comprises a set of instructions for performing a set of image editing operations on the image with a set of tools of the image-editing application.

Description:
CLAIM OF BENEFIT TO PRIOR APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application 61/607,550, entitled “Application for Viewing Images”, filed Mar. 6, 2012. U.S. Application 61/607,550 is incorporated herein by reference. 
    
    
     BACKGROUND 
     Digital image editing and viewing applications provide photographers, both professional and amateur, with tools to both organize and edit their photos. These applications give users the ability to organize collections of photos and to modify various image properties of the photos in a variety of ways. 
     In the modern world, touchscreen devices are becoming ubiquitous. Many tablets and smartphones on the market use touchscreens, and many people own such a touchscreen device. In addition, many users both take photographs with their portable touchscreen devices and load photographs from other sources (e.g., digital cameras) onto their portable touchscreen devices. As such, an application is needed for viewing, organizing, and editing photos that is adapted to the unique controls available for a touchscreen device. 
     BRIEF SUMMARY 
     Some embodiments of the invention provide a novel application for viewing and working with images. In some embodiments, the application operates in multiple different modes, with different graphical user interfaces (GUIs) for the different modes. For instance, in some embodiments, the application operates on a touch device in both left-handed and right-handed modes. In addition to the different GUIs for the different modes, some embodiments present specific user interface tools in different manners (e.g., different orientations) in the different modes. The application provides various features for working with one or multiple images. For instance, some embodiments enable various methods for viewing multiple different images, including (i) novel touch interactions for selecting multiple items and (ii) novel methods for identifying similar images from a group of images. In addition, the application provides various novel interactions for working with multiple selected images, such as interactions for cycling through images and tagging images. 
     As mentioned, the application of some embodiments provides multiple different modes (e.g., left-handed and right-handed modes). Some embodiments switch between modes according to the location in the GUI of a particular GUI item. When switching between modes, some embodiments preserve a relationship in the GUI (e.g., an order) of a first set of GUI items while modifying a relationship of a second set of GUI items. In addition, the application of some embodiments presents certain tools in different manners (e.g., orientations) when the tools are activated in the different modes. 
     In some embodiments, the application provides a user-interface mechanism for switching between the modes. For example, the GUI of some embodiments includes a thumbnail display area that displays thumbnails of a group of images and an image display area that displays larger (and in some cases, editable) versions of selected images. In some embodiments, the thumbnail display area is moveable, and the application switches between left- and right-handed modes based on the location in the GUI to which the thumbnail display area is moved (e.g., left-handed mode when the thumbnail display area is on the right side of the GUI and right-handed mode when the thumbnail display area is on the left side of the GUI). 
     When the application switches between the two modes, some embodiments preserve the order of a first set of GUI items while changing the order of a second set of GUI items. Specifically, the application preserves the order of a set of GUI items associated with various editing tools to maintain an order in which the editing tools are typically utilized. On the other hand, the application reverses the order of a second set of GUI items in order to keep the GUI items in the same location relative to the thumbnail display area. 
     In addition, the image viewing, editing, and organization application provides certain GUI tools in different manners in the different modes. For instance, some embodiments display specific tools in different orientations depending on whether the application is in left- or right-handed mode. One such specific tool is a zoom tool that magnifies a particular area of the image display area. The zoom tool of some embodiments is a circular magnifier capable of varying degrees of magnification. To modify the magnification, the user performs a rotation gesture of two separate touch inputs (e.g., with the thumb and index finger). When operating in right-handed mode, the application displays magnification information on the left side of the magnifier, and vice versa when operating in left-handed mode. This prevents the user&#39;s hand from blocking the view of the magnification information on the zoom tool. Furthermore, some embodiments switch the directions of rotation for zooming in and out between the two different modes. 
     As mentioned, in some embodiments, the thumbnail display area is moveable between two different sides of the application GUI. In addition, the application enables the user to move the thumbnail display area on and off the application GUI via swipe gestures (e.g., right and left swipe gestures on a touchscreen). Furthermore, users can modify the size (and number of columns of thumbnails) of the thumbnail display by moving the boundary between the thumbnail display area and the image display area with a drag gesture on the touchscreen. 
     In addition to operating in different modes, the image viewing, editing, and organization application provides a variety of novel operations and interactions for viewing and working with images. For instance, some embodiments enable several different operations for selecting multiple images to display in the image display area. One such operation involves simultaneous selection (e.g., via two different touch inputs) of first and second thumbnails in the thumbnail display area in order to select the first and second thumbnails and all thumbnails in between. In response to such a block selection, the application displays all of the images corresponding to the selected thumbnails in the image display area. 
     Some embodiments additionally differentiate between different types of thumbnail selection inputs. For example, when a user selects a particular thumbnail in a first manner (e.g., a tap on a touchscreen or a single click), the application selects only the particular thumbnail and displays only its corresponding image in the display area. However, when a first thumbnail is already selected and a user selects a second thumbnail in a second manner (e.g., with a press and hold on a touchscreen or a click and hold), the application maintains the selection of the first thumbnail while selecting the second thumbnail. The application displays both the first and second images (and any other selected images) in the image display area. In this manner, some embodiments allow the user to add any number of images to the image display area. 
     Furthermore, the image viewing, editing, and organization application of some embodiments can display all images that are similar to a selected image according to a particular set of criteria. When a user selects an image in a third manner (e.g., via a double tap on a touchscreen, a double-click, etc.), the application compares all images in a collection of associated images (e.g., the images whose thumbnails are eligible for display in the thumbnail display area) to the selected image, and identifies which of the images are within a threshold similarity to the selected image according to the particular set of criteria. Some embodiments generate histograms of the pixels of an image (e.g., based on color, texture, and gradient values for the pixels) and compare the histograms to identify similar images. In some embodiments, the application generates different histograms for different regions of the images and compares the histograms of corresponding regions. The images are divided into the regions in such a way that some pixels are part of multiple regions while other pixels are part of only one region. This enables the application to give greater consideration to the pixels that are more indicative of the content of the image (e.g., those in the center) in making the comparison between two images. 
     When displaying multiple images in the image display area, some embodiments maintain a constant visual weight between the different images. That is, rather than try to fill all of the space in the image display area by displaying the images as different sizes, the application displays each image as the same size irrespective of the dimensions of the image. In order to keep the visual weighting constant between different images, some embodiments calculate the average aspect ratio of all of the images to display in the image display area, then identify an optimal division of the image display area into the correct number of regions having the average aspect ratio. Within these regions, the application then displays the images such that each image is displayed using the same number of pixels. 
     Once multiple thumbnails are selected and multiple images displayed in the image display area, some embodiments provide various novel interactions for viewing and interacting with the images. For instance, a user can perform a selection operation (e.g., a tap on a touchscreen, a mouse click) on one of the displayed images. Some embodiments display only the selected image (i.e., the primary selection image) in the image display area, but maintain secondary selection of the other images. To indicate these selections, the application highlights the thumbnails of the secondary image selections with a first selection indicator, while highlighting the thumbnail of the primary selection image (the displayed image) with a second selection indicator (e.g., using thick and thin highlighted boundaries). 
     When in this viewing mode for multiple images, some embodiments allow the user to cycle through the different selected images with horizontal swipe gestures. In addition, the user can remove an image from the set of selected images with a vertical swipe gesture. When an image is removed from the set, the application removes the selection indicator from the corresponding thumbnail. When multiple images are displayed in the image display area, the user can apply a tag (e.g., a favorites tag) to all of the images, or select one of the images for primary display and then apply a tag to only the primary image selection. 
     While viewing images, the application of some embodiments allows the user to interact bidirectionally with image hosting and social media websites. For instance, the user can add a caption to an image, which is attached to the image both within the image-viewing application as well as when the image is exported to an external application or website. Furthermore, when a user of an external website comments on the hosted image, some embodiments automatically retrieve this information and display the external comments within the image-viewing application. 
     In addition to the above-described features, the application of some embodiments provides a context-sensitive help feature. Specifically, when a help tool is invoked, the application displays help indicators that are tailored to the items with which a user is currently working. When a user changes the active set of tools in use, the application displays help indicators for the active set of tools. For moveable tools (e.g., sliders), some embodiments move the help indicators along with the tools as the tools are moved. 
     The preceding Summary is intended to serve as a brief introduction to some embodiments of the invention. It is not meant to be an introduction or overview of all inventive subject matter disclosed in this document. The Detailed Description that follows and the Drawings that are referred to in the Detailed Description will further describe the embodiments described in the Summary as well as other embodiments. Accordingly, to understand all the embodiments described by this document, a full review of the Summary, Detailed Description and the Drawings is needed. Moreover, the claimed subject matters are not to be limited by the illustrative details in the Summary, Detailed Description and the Drawings, but rather are to be defined by the appended claims, because the claimed subject matters can be embodied in other specific forms without departing from the spirit of the subject matters. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The novel features of the invention are set forth in the appended claims. However, for purpose of explanation, several embodiments of the invention are set forth in the following figures. 
         FIG. 1  illustrates two different modes of a GUI for an image-viewing application of some embodiments. 
         FIG. 2  illustrates the selection of multiple images to simultaneously display within the image display area of a GUI. 
         FIG. 3  illustrates a process for displaying all images that are similar to a selected image according to a particular set of criteria. 
         FIG. 4  illustrates the application of a tag to images in a GUI. 
         FIG. 5  illustrates the use of a context-sensitive help feature in a GUI. 
         FIG. 6  illustrates the creation of a new collection of images according to some embodiments. 
         FIG. 7  conceptually illustrates a process of some embodiments for creating a new collection of images (e.g., an album). 
         FIG. 8  conceptually illustrates a collection data structure  800  of some embodiments. 
         FIG. 9  illustrates navigation between the image organization, viewing, and editing GUI and the collection organization GUI. 
         FIG. 10  illustrates a user navigating within the collection organization GUI to view a newly created album. 
         FIG. 11  illustrates a user navigating through the collection organization GUI over according to some embodiments. 
         FIG. 12  illustrates a vertical scrolling technique according to some embodiments. 
         FIG. 13  illustrates navigation between the image viewing and editing GUI and the collection organization GUI over four stages for the mobile phone and media player implementation of some embodiments while in portrait mode. 
         FIG. 14  illustrates a detailed view of a GUI of some embodiments for viewing, editing, and organizing images. 
         FIG. 15  conceptually illustrates a data structure for an image as stored by the application of some embodiments. 
         FIG. 16  illustrates a GUI over four stages in which the user moves a thumbnail display area from the left side to the right side of the GUI in order to switch from right-handed mode to left-handed mode. 
         FIGS. 17-19  illustrate left-handed and right-handed GUI modes of some embodiments, in both portrait and landscape mode. 
         FIG. 20  conceptually illustrates a state diagram showing states and changes in the state for the thumbnail display area in the image viewing GUI of some embodiments. 
         FIG. 21  illustrates a user increasing the size of the thumbnail display area. 
         FIG. 22  illustrates a user decreasing the size of the thumbnail display area. 
         FIG. 23  illustrates a swipe gesture to remove the thumbnail display area from the GUI while in the right-handed GUI mode. 
         FIG. 24  illustrates a similar swipe gesture to remove the thumbnail display area from the GUI while in the left-handed mode. 
         FIG. 25  illustrates the selection of a GUI item that causes the thumbnail display area to slide off of the GUI. 
         FIG. 26  illustrates a swipe gesture to return the thumbnail display area to the GUI while in the right-handed GUI mode. 
         FIG. 27  illustrates a similar swipe gesture to return the thumbnail display area to the GUI while in the left-handed GUI mode. 
         FIG. 28  illustrates the selection of a GUI item that causes the thumbnail display area to slide onto the GUI. 
         FIG. 29  illustrates a user scrolling through the thumbnail display area. 
         FIG. 30  illustrates a portrait mode GUI as a user scrolls through the thumbnails of a collection in the thumbnail display area. 
         FIG. 31  illustrates the modification of the size of the thumbnail display area in the portrait GUI. 
         FIG. 32  illustrates the horizontal scrolling of the thumbnail display area when sized down to one row. 
         FIG. 33  illustrates a user scrolling through images in the thumbnail display area of the mobile phone and media player GUI of some embodiments. 
         FIG. 34  conceptually illustrates a process of some embodiments for invoking a zoom tool. 
         FIG. 35  illustrates an example of invoking and deselecting a zoom tool through the right-handed GUI of some embodiments. 
         FIG. 36  illustrates an example of invoking a zoom tool through the GUI when the GUI is in a left-handed mode. 
         FIG. 37  conceptually illustrates state diagram that presents various operations of a zoom tool in some embodiments. 
         FIG. 38  illustrates the magnification operation of the zoom tool in a right-handed GUI. 
         FIG. 39  illustrates the de-magnification operation of the zoom tool in a right-handed GUI. 
         FIG. 40  illustrates the move operation of the zoom tool. 
         FIG. 41  illustrates the magnification operation of the zoom tool in a left-handed GUI. 
         FIG. 42  illustrates the de-magnification operation of the zoom tool in a left-handed GUI. 
         FIG. 43  conceptually illustrates a process of some embodiments for identifying and displaying similar images within a collection. 
         FIG. 44  illustrates a GUI for an image viewing application in which a user selects a particular image and the application identifies the set of images within a collection that are similar to the selected image. 
         FIG. 45  conceptually illustrates a division of an image into nine different tiles, each of which is one-fourth the size of the image. 
         FIG. 46  indicates the sixteen quadrants of pixels that result from this particular division of the image, and which of the tiles include pixels from each quadrant. 
         FIG. 47  conceptually illustrates a process  4700  for generating a set of histograms according to some embodiments of the invention. 
         FIG. 48  conceptually illustrates the HSV color space  4800 . 
         FIG. 49  illustrates a circular cross section of the HSV color space (i.e., at a constant value), with two regions defined. 
         FIG. 50  illustrates a three-dimensional portion of the HSV color space divided into two regions. 
         FIG. 51  illustrates nine pixels used by some embodiments to calculate the texture for the center pixel. 
         FIG. 52  conceptually illustrates the software architecture of portions of the image viewing, editing, and organization application of some embodiments that generate histograms and compare images for similarity. 
         FIG. 53  conceptually illustrates a process of some embodiments for selecting a block of thumbnails within the image display area. 
         FIGS. 54 and 55  illustrate examples of the selection of blocks of thumbnails. 
         FIG. 56  conceptually illustrates a process of some embodiments for translating user input over an unselected thumbnail into a selection of the thumbnail. 
         FIG. 57  illustrates various selection inputs in the GUI of some embodiments. 
         FIG. 58  illustrates a similar set of selection operations in the mobile phone and media player GUI of some embodiments. 
         FIG. 59  conceptually illustrates a process of some embodiments for displaying multiple images simultaneously within an image display area. 
         FIG. 60  illustrates a GUI in which the user makes a block selection of four thumbnails. 
         FIG. 61  illustrates the average aspect ratio region of the four selected images. 
         FIG. 62  illustrates that the ideal number of columns for a 187:144 aspect ratio region within the 4:3 image display area  6005  is two, with two rows. 
         FIG. 63  illustrates the different aspect ratio images fit within the grid region. 
         FIG. 64  illustrates the sizes of the images when fit to occupy the same area in the image display area as a particular one of the other images. 
         FIG. 65  illustrates the four images displayed within the image display area. 
         FIG. 66  conceptually illustrates a state diagram that describes different states and transitions between these states of the GUI of some embodiments relating to the selection/deselection of images and viewing of selected images. 
         FIG. 67  illustrates a transition from displaying multiple selected images in the GUI to displaying one of the selected images as the active image. 
         FIG. 68  illustrates a series of rightward swipe gestures in the GUI in order to cycle between selected images. 
         FIG. 69  illustrates a leftward swipe gesture in the GUI in order to cycle between selected images. 
         FIG. 70  illustrates a downward swipe gesture in the GUI of some embodiments. 
         FIG. 71  illustrates examples of a user tapping on the selected thumbnails in the GUI. 
         FIG. 72  conceptually illustrates a state diagram for the GUI of some embodiments relating to the application of a tag in three different states. 
         FIG. 73  illustrates the application of the hide image tag to an image. 
         FIG. 74  illustrates the application of a flag image tag to an image. 
         FIG. 75  illustrates the application of the flag image tag to multiple images. 
         FIG. 76  illustrates the use of the tag filtering button. 
         FIG. 77  illustrates the application of the favorites tag to an image. 
         FIG. 78  illustrates the application of the favorites tag to multiple images. 
         FIG. 79  conceptually illustrates a process performed by the application of some embodiments upon receipt of a tag to apply to an image. 
         FIG. 80  illustrates a user navigating from an album to a collection of favorite images. 
         FIGS. 81-83  illustrate the access of image information for one or more images in the GUI. 
         FIG. 84  illustrates a user adding a caption to an image. 
         FIG. 85  illustrates user interaction with a GUI in order to share an image via a social media site according to some embodiments. 
         FIG. 86  conceptually illustrates a process of some embodiments for sharing an image via a social media or photo sharing website. 
         FIGS. 87A-87C  illustrate a user uploading an image to Facebook®. 
         FIG. 88  illustrates a user selecting two images for upload to Facebook®, including an edited version of the image uploaded in  FIGS. 87A-87C . 
         FIG. 89  conceptually illustrates a process of some embodiments for retrieving comments posted to an image on a photo sharing or social media website. 
         FIG. 90  illustrates a user posting a comment to a shared image through the information window in the GUI of some embodiments. 
         FIG. 91  conceptually illustrates a state diagram that presents various operations of the help feature in some embodiments. 
         FIG. 92  illustrates an example of displaying the help icon in a conspicuous manner according to some embodiments. 
         FIG. 93  illustrates an example of invoking the help tool. 
         FIG. 94  illustrates an example of modifying the help tool level when the user selects a new set of tools within the GUI. 
         FIG. 95  illustrates an example of the application automatically moving a help indicator along with a corresponding tool. 
         FIG. 96  illustrates an example of displaying a detailed help article related to one of the GUI items. 
         FIG. 97  illustrates another example of the display of help indicators for different GUI items in some embodiments. 
         FIG. 98  conceptually illustrates the software architecture of an image viewing, editing, and organization application of some embodiments. 
         FIG. 99  is an example of an architecture of a mobile computing device on which some embodiments are implemented. 
         FIG. 100  conceptually illustrates an electronic system with which some embodiments are implemented. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description, numerous details, examples and embodiments are set forth for purpose of explanation. However, one of ordinary skill in the art will realize that the invention is not limited to the embodiments set forth and that the invention may be practiced without some of the specific details and examples discussed. In other instances, well-known structures and devices are shown in block diagram form in order not to obscure the description of the invention with unnecessary detail. 
     Some embodiments of the invention provide a novel application for viewing and working with images. In some embodiments, the application operates in multiple different modes, with different graphical user interfaces (GUIs) for the different modes. For instance, in some embodiments, the application operates on a touchscreen device in both left-handed and right-handed modes. In addition to the different GUIs for the different modes, some embodiments present specific user interface tools in different manners (e.g., different orientations) in the different modes. The application provides various features for working with one or multiple images. For instance, some embodiments enable various methods for viewing multiple different images, including (i) novel touch interactions to select multiple items and (ii) novel methods for identifying similar images from a group of images. In addition, the application provides various novel interactions for working with multiple selected images, such as interactions for cycling through images and tagging images. 
     As mentioned, the image editing, viewing, and organization application (referred to below as an image-viewing application, an image-editing application, etc.) of some embodiments provides multiple different modes (e.g., left-handed and right-handed modes). Some embodiments switch between modes according to the location in the GUI of a particular GUI item. When switching between modes, some embodiments preserve a relationship in the GUI (e.g., an order) of a first set of GUI items while modifying a relationship of a second set of GUI items. In addition, the application of some embodiments presents certain tools in different manners (e.g., orientations) when the tools are activated in the different modes. 
       FIG. 1  illustrates two different modes of such a GUI  100  for an image-viewing application of some embodiments. Specifically, this figure illustrates the GUI  100  in a right-handed mode in two stages  110  and  120 , while illustrating the GUI  100  in a left-handed mode in two stages  130  and  140 . 
     The GUI  100  includes a thumbnail display area  105 , an image display area  115 , a first set of GUI items  125 , and a second set of GUI items  135 . The thumbnail display area  105  displays thumbnails of a set of images (e.g., a user-created album or other collection of associated images). The thumbnails are scaled down versions of the images in the collection. In some embodiments, the thumbnails do not necessarily display entire images, but instead display only a portion of each image so that each thumbnail has the same aspect ratio (e.g., a square). Users can select thumbnails (e.g., via a touch interaction, a mouse click, etc.) in order to cause the corresponding image to appear in the image display area  115 . 
     The image display area  115  displays larger versions of one or more selected images. In this case, the thumbnail  107  is selected in the thumbnail display area  105 , and thus the corresponding image is displayed in the image display area  115 . As shown, some embodiments display an indication for each of any selected thumbnails in the thumbnail display area. In this case, the thumbnail  107  is shown with a thick dashed border; however, one of ordinary skill in the art will recognize that many different selection indications are possible. 
     In addition to providing viewing functionality in the image display area, some embodiments provide the user with various editing, tagging, and other operations to apply to the displayed images. The first set of GUI items  125  includes three items  126 - 128  that activate different sets of editing tools for editing images. The items  126 - 128  are arranged in a particular left to right order that follows the order in which a user will often want to make edits to the image. The second set of GUI items  135  includes three items  136 - 138  that are arranged in an order designed to provide functionality based on relative location to the other items in the GUI (e.g., the thumbnail display area  105  and image display area  115 ). 
     As stated, stage  110  illustrates the GUI  100  in the right-handed mode. In this mode, the thumbnail display area  105  is on the left side of the GUI. In addition, the GUI items  126 - 128  are arranged on the left side of the GUI, with item  126  on the left, item  127  in the center, and item  128  on the right. The GUI items  136 - 138  are arranged on the right side of the GUI, with item  136  on the left, item  137  in the center, and item  138  on the right. 
     The stage  130  illustrates the GUI in the left-handed mode. In this case, the thumbnail display area  105  is located on the right side of the GUI. This ensures that when a user moves her left hand over the GUI, her arm will not block the view of the thumbnail display area. Similarly, with the thumbnail display area  105  located on the left side of the GUI in right-handed mode, the user&#39;s right arm will not block their view of the thumbnail display area  105 . 
     In the stage  130 , the first set of GUI items  125  are located on the right side of the GUI  100  underneath the thumbnail display area  105 , while the second set of GUI items  125  are located on the left side of the GUI  100 . However, the first set of items  125  maintains the same left-to-right order that matches the order in which a user typically will use the associated editing tools, while the order is reversed for the second set of items  135  as compared to these items in right-handed mode. 
     In some embodiments, the application provides a user-interface mechanism for switching between these two modes. For example, in some embodiments the thumbnail display area is moveable, and the application switches between the left- and right-handed modes based on the location in the GUI to which the thumbnail display area is moved. In order to get from the stage  110  to the stage  130 , the user could pick up and drag the thumbnail display area  105  from the left side of the touchscreen display to the right side of the touchscreen display. Upon doing so, the application automatically moves the first and second sets of tools  125  and  135 , and reverses the order of the second set of tools  135 . 
     In addition, the image-viewing application provides certain GUI tools in different manners in the different modes. For instance, some embodiments display specific tools in different orientations depending on whether the application is in left- or right-handed mode.  FIG. 1  illustrates an example of such a GUI tool  145  that is activated in different orientations in the two different modes. In this case, the GUI tool  145  is a zoom tool that magnifies a particular area of the image display area. 
     As shown, in the stage  110 , a user interacts with the image display area with their right hand in order to activate the zoom tool  145 . While this figure shows a one-finger interaction, different embodiments respond to different types of inputs in order to activate such a tool. For example, some embodiments require two separate touch interactions that coincide at least partially in time in order to activate a zoom tool. 
     Stage  120  illustrates the result of this interaction while in the right-handed display mode. The application displays the zoom tool  145  over the location of the user&#39;s touch interaction. As shown, the application displays the tool  145  in a first orientation, with the + sign (indicating greater magnification) on the right and the − sign (indicating less magnification) on the left. 
     Correspondingly, in the stage  130 , the user interacts with the image display area with their left hand in order to activate the zoom tool  145 . The stage  140  illustrates the result of this interaction while in the left-handed display mode. As in stage  120 , the application displays the zoom tool  145  over the location of the user&#39;s touch interaction. In this case, however, the application displays the zoom tool  145  in a second orientation, with the + sign on the left and the − sign on the right. 
     In some embodiments, the zoom tool is capable of varying degrees of magnification. To modify the magnification, the user performs a rotation gesture of two separate touch inputs (e.g., with the thumb and index finger). In some embodiments, when the application is operating in right-handed mode, clockwise rotation increases the magnification while counter-clockwise rotation decreases the magnification. When in left-handed mode, the opposite is true, with counter-clockwise rotation increasing the magnification and clockwise rotation decreasing the magnification. 
     Furthermore, some embodiments display magnification information (e.g., the level of magnification inside the active tool) as part of the tool. When in right-handed mode, this magnification information is displayed on the left side of the magnifier, while in left-handed mode the information is displayed on the right side of the magnifier. This prevents the user&#39;s hand from blocking the view of the magnification information on the zoom tool while zooming in or out. 
     As mentioned, in some embodiments, the thumbnail display area is moveable between two different sides of the application GUI. In addition, the image-editing application enables the user to move the thumbnail display area on and off the application GUI via swipe gestures (e.g., right and left swipe gestures on a touchscreen). Furthermore, users can modify the size (and number of columns of thumbnails) of the thumbnail display area by moving the boundary between the thumbnail display area and the image display area with a drag gesture on the touchscreen. 
     In addition to operating in different modes, the image-viewing application provides a variety of novel operations and interactions for viewing and working with images. For instance, some embodiments enable several different operations for selecting multiple images to display in the image display area.  FIG. 2  illustrates the selection of multiple images to simultaneously display within the image display area of a GUI  200  over four stages  210 - 240 . 
     The GUI  200  includes a thumbnail display area  205  and an image display area  215 , which are similar to the corresponding display areas described above for the GUI  100 . In this figure (and many other figures in this application) the GUI is shown in right-handed mode, with the thumbnail display area to the left. One of ordinary skill will recognize that many of the interactions shown are equally applicable to the left-handed GUI mode. 
     The first stage  210  illustrates that a thumbnail  225  has been selected, and the corresponding selected image  227  is displayed at the largest possible size in the image display area (while maintaining the aspect ratio of the image). In the second stage  220 , the user selects a second thumbnail  235  corresponding to a second image  237  via a touch interaction. One of ordinary skill in the art will recognize that touchscreen devices provide the ability to differentiate between various types of interactions (e.g., taps, double taps, press and hold, separate simultaneous interactions, multi-finger interactions, etc.). 
     The third stage  230  illustrates that the image display area  215  now displays both of the selected images  227  and  237 . Furthermore, the application displays the thumbnails  225  and  235  with a lighter dashed boundary than in the previous stage. Some embodiments use different selection indications in the thumbnail display area (e.g., thick and thin borders or highlights, different colors, etc.) to differentiate between a single selected image and multiple selected images. 
     The two images  227  and  237  shown in the image display area  215  do not have the same aspect ratio, but are displayed as approximately the same size. When displaying multiple images in the image display area, some embodiments maintain a constant visual weight between the different images. That is, rather than trying to fill all of the space in the image display area by displaying the images as different sizes, the application displays each image as the same size irrespective of the dimensions of the image. In order to keep the visual weighting constant between different images, some embodiments calculate the average aspect ratio of all of the images to display in the image display area, then identify an optimal division of the image display area into the correct number of regions having the average aspect ratio. Within these regions, the application then displays the images such that each image is displayed using the same number of pixels. 
     The third stage  230  also illustrates the user selecting a third thumbnail  245  corresponding to an image  247  via another touch interaction. As a result, in the fourth stage  240 , the image display area  215  displays the three selected images  227 ,  237 , and  247 . In order to display the third image, the application has not had to reduce the size of the other two images, as the same visual weighting for the three images could be maintained without a size reduction. 
     As mentioned, some embodiments respond to various different touch interactions in order to display multiple images in the image display area. One such touch operation involves simultaneous selection (e.g., via two different touch inputs) of first and second thumbnails in the thumbnail display area in order to select the first and second thumbnails and all thumbnails in between. In response to such a block selection, the application displays all of the images corresponding to the selected thumbnails in the image display area. 
     Some embodiments additionally differentiate between different types of thumbnail selection input. For example, when a user selects a particular thumbnail in a first manner (e.g., a tap on a touchscreen or a single click), the application selects only the particular thumbnail and displays only its corresponding image in the display area. However, when a first thumbnail is already selected and a user selects a second thumbnail in a second manner (e.g., with a press and hold on a touchscreen or a click and hold), the application maintains the selection of the first thumbnail while selecting the second thumbnail. The application displays both the first and second images (and any other selected images) in the image display area. In this manner, some embodiments allow the user to add any number of images to the image display area. 
     Furthermore, the image-viewing application of some embodiments can display all images that are similar to a selected image according to a particular set of criteria.  FIG. 3  illustrates such a process over three stages  310 - 330  of a GUI  300 . The GUI  300  includes a thumbnail display area  305  and an image display area  315 , similar to the corresponding areas of the previous figures. 
     The first stage  310  of  FIG. 3  illustrates that a thumbnail  335  is selected and its corresponding image  340  is displayed in the image display area  315 . In the second stage  320 , the user has performed a touch operation on the selected thumbnail  335 . One of ordinary skill in the art will recognize that this is a generic user input, and that other embodiments might provide for the activation of the similar images feature differently (e.g., a double tap or double click of a thumbnail (whether or not already selected), a hotkey or sequence of hotkeys, a touch gesture or sequence of gestures, a menu item or UI button, etc.). The third stage  330  illustrates that the application has identified images similar to the selected image  340  and displayed the identified images  345  and  350  in the image display area  315 . Furthermore, the corresponding thumbnails  335 ,  355 , and  360  are all selected in the thumbnail display area  305 , as shown by the dashed lines. 
     To identify these similar images, some embodiments compare all images in a collection of associated images (e.g., the images whose thumbnails are eligible for display in the thumbnail display area) to the selected image, and identify which of the images are within a threshold similarity of the selected image according to the particular set of criteria. Some embodiments generate histograms of the pixels of an image (e.g., based on color, texture, and gradient values for the pixels) and compare the histograms to identify similar images. In some embodiments, the application generates different histograms for different regions of the images and compares the histograms of corresponding regions between images. The images are divided into the regions in such a way that some pixels are part of multiple regions while other pixels are part of only one region. This enables the application to give greater consideration to the pixels that are more indicative of the content of the image (e.g., those in the center of the image) in making the comparison between two images. 
     Once multiple thumbnails are selected and multiple images are displayed in the image display area, some embodiments provide various novel interactions for viewing and interacting with the images. For instance, a user can perform a selection operation (e.g., a tap on a touchscreen, a mouse click) on one of the displayed images (rather than its corresponding thumbnail). Some embodiments display only the selected image (i.e., the primary selection image) in the image display area, but maintain secondary selection of the other images. To indicate these selections, the application highlights the thumbnails of the secondary image selections with a first selection indicator, while highlighting the thumbnail of the primary selection image (the displayed image) with a second selection indicator (e.g., using thick and thin highlighted boundaries). 
     When in this viewing mode for multiple images, some embodiments allow the user to cycle through the different selected images with horizontal swipe gestures. In addition, the user can remove an image from the set of selected images with a vertical swipe gesture. When an image is removed from the set, the application removes the selection indicator from the corresponding thumbnail. When multiple images are displayed in the image display area, the user can apply a tag (e.g., a favorites tag) to all of the images, or select one of the images for primary display and then apply a tag to only the primary image selection. 
       FIG. 4  illustrates the application of such a tag to the images  340 - 350  in the GUI  300  over three stages  410 - 430 . The first stage  410  illustrates the GUI  300  in the same state as the third stage  330  of  FIG. 3 , with the images  340 - 350  displayed in the image display area  315 . At the second stage  420 , the user selects a GUI item  405  for applying a tag to the selected images. The GUI item  405  is a conceptual item, and some embodiments of the image-editing application might implement such a functionality through a different UI item, a particular type of selection gesture, hotkeys, etc. Furthermore, the item  405  represents a generic tag, while some embodiments might include various different tags, such as a favorites tag, a flag, custom information tags, etc. 
     The third stage illustrates the result of the selection of the GUI item  405 . The three thumbnails  335 ,  355 , and  360  now display a marker indicating that they have been tagged. In some embodiments, the application displays icons for some tags within the thumbnails, while simply storing other tags as properties of the tagged images. In addition, the GUI item  405  is now highlighted, indicating that all of the selected images have been tagged. Some embodiments indicate that all of the images displayed in the display area are tagged with a particular tag by highlighting the tag button in the GUI. A subsequent selection of the tag button removes the tag from the selected images. 
     While viewing images, the application of some embodiments also allows users to interact bidirectionally with image hosting and social media websites. For instance, users can add a caption to an image, which is attached to the image both within the image-viewing application as well as when the image is exported to an external application or website. Furthermore, when a user of an external website comments on the hosted image, some embodiments automatically retrieve this information and display the external comments within the image-viewing application. 
     In addition to the above-described features, the application of some embodiments provides a context-sensitive help feature. Specifically, when a user invokes a help tool, the application displays help indicators that are tailored to the items with which a user is currently working.  FIG. 5  illustrates the use of such a context-sensitive help feature in the GUI  100  over four stages  510 - 540 . The GUI includes a help activation item  137  for invoking the context-sensitive help feature. The first stage shows the GUI  100  with one selected image displayed in the image display area  115 . 
     In the second stage  520 , the user selects the help activation item  137  via a touch interaction. As with the other GUI items described above, the help activation item  137  is a conceptual item that could actually be invoked in a variety of different manners, including various touch interactions, cursor interactions, etc. 
     The third stage  530  illustrates that the help activation item  137  is now active, and help indicators  505  have appeared for the GUI items  126 - 128 . These help indicators  505  display the purpose of the different GUI items, and in some embodiments are selectable in order to access a help manual with additional information about the selected item. The third stage also illustrates the user selecting the exposure item  127 . 
     When a user changes the active set of tools in use, the application displays help indicators for the active set of tools. As a result, the fourth stage  540  shows a different set of help indicators  515 . These help indicators  515  display the purpose of the different exposure adjustment items that have appeared in the GUI  100 . The help indicators  505  for the crop, exposure, and color items are no longer displayed, because the user has navigated into a specific one of these sets of editing tools. In addition, for moveable tools (e.g., the exposure adjustment sliders), some embodiments move the help indicators along with the tools as the user moves the tools. 
       FIGS. 1-5  illustrate various examples of the novel features provided by some embodiments for viewing and working with images. Several more detailed embodiments are described below. Section I describes image collections and navigating between different groups of collections within the application. Before describing different GUI modes and various interactions with the GUI in the different modes in Section III, Section II describes the GUI and image data structure of some embodiments. Section IV then describes different techniques for selecting multiple images and how the application of some embodiments displays multiple images at once. Section V describes various operations that may be applied to one or more operations in some embodiments, including selection and deselection operations and tagging operations. Next, Section VI describes an image sharing feature and Section VII describes a context-sensitive help feature of some embodiments. Section VIII then describes the software architecture of the media-editing application of some embodiments. Finally, Section IX describes an electronic system with which some embodiments of the invention are implemented. 
     I. Image Collections 
     Before describing the various features involved in working with collections of images, this application will describe the creation and organization of such collections according to some embodiments of the invention. The image editing, viewing, and organization application of some embodiments enables users to import images (e.g., photographs), associate the images into collections (e.g., albums, etc.), create shareable media (e.g., journals) from the images, edit the images, etc. Some embodiments automatically associate images imported together from a separate device (i.e., a device other than the device on which the application runs) as an event. Albums, on the other hand, are user-created collections of images. While the media organized by the application is described predominantly herein as images, some embodiments of the invention also organize, view, and edit other types of media, such as videos. 
       FIG. 6  illustrates the creation of a new collection of images over four stages  610 - 640  according to some embodiments. Specifically, the stages illustrate a user selecting a particular event collection, selecting several images within the event, and then forming an album from the selected images. In this figure, as well as many others within this document, user interactions are shown in a first stage and the resulting change in the GUI shown in the subsequent stage, for explanatory purposes. However, one of ordinary skill in the art will recognize that in most cases, the delay between receiving a user interaction and the change in the display will be nearly instantaneous. 
     The first stage  610  illustrates a collection organization GUI  600  for displaying the collections of images available on the device. The GUI  600  includes a set of tabs  605  that allow a user to switch between different types of collections. The tabs  605  allow a user to choose albums (user-created collections of images), photos (one collection that amalgamates all of the images from the various other collections), events (collections of images that were imported together to the device on which the image-viewing application operates), and journals (a specific way of presenting and sharing collections of images). In some embodiments, the user can select the different tabs  605  to switch between the different types of collections. One of ordinary skill in the art will recognize that some embodiments include different tabs (e.g., a specific videos tab, tabs for other types of shareable collections, etc.). 
     The GUI  600  also includes shelves  615  that display icons representing the various collections available to a user. In some embodiments, the shelves  615  are displayed to give a three-dimensional appearance of glass shelves, with reflections and shadows. The icons representing albums, photos, events, and journals have the appearance of resting on the glass shelves and casting shadows that are seen in the GUI. At stage  610 , the GUI includes an icon  625  representing a collection of images called “Event  2 ” that the user selects (in this case, through a touch operation). 
     The second stage  620  illustrates a GUI  650  that results from the user selecting the icon  625 , as well as the results of additional selections within the resultant GUI  650 . When a particular collection is selected, the application displays a GUI for the particular collection. The GUI  650  includes a thumbnail display area  655 , an image display area  660 , as well as various other GUI items that will be described in further detail below by reference to  FIG. 14 . The GUI  650  also displays, at its top, the name of the collection that it is displaying (in this case, “Event  2 ”). 
     In this stage, the user has selected three thumbnails in the thumbnail display area  655 , and the application displays the three corresponding images in the image display area  660 . Details regarding different manners of selecting multiple images will be described in detail below in Section IV. 
     In the third stage  630 , the user selects a settings GUI item  665  (e.g., via a touch interaction, a cursor controller, etc.). The settings item, in some embodiments, activates a menu that is based on the context of the user&#39;s previous actions within the application. For instance, when the user has activated a particular set of editing tools, the settings menu may include options related to the activated editing tools. 
     In this case, however, the user is in a viewing mode, and the settings menu includes an option of “Create new album”. The fourth stage  640  illustrates the user selecting this menu option to create a new album. In some embodiments, selecting this option causes the application to create a new album from the selected images. Some embodiments include other options related to albums in the settings menu, such as adding selected images to a previously-created album. In addition, some embodiments provide different mechanisms for creating a new album. For instance, in some embodiments, a user can create a new album through the collections organization GUI  600 , then add new images to the album by accessing a different collection. 
     Furthermore, upon creating a new album, some embodiments display a new window or dialog box through which the user can set the parameters of the new album. For instance, users can enter an album name and, in some cases, determine whether to include all selected images, all images in the present collection, or choose images from another collection, as well as other options. 
     Some embodiments, however, do not provide the option to create new albums. Albums can be imported into the image-viewing application from additional applications running on the same device (e.g., a separate image organization application). Instead, the only form of collection that the user may create from a selection of several images is a journal. In addition, by flagging an image or setting an image as a favorite, the user causes the image to be added to an album specific to those tags. 
       FIG. 7  conceptually illustrates a process  700  of some embodiments for creating a new collection of images (e.g., an album). As shown, the process  700  begins by receiving (at  705 ) a command to create a new collection of images. In some embodiments, this command is a user command such as the “Create new album” menu option shown in  FIG. 6 , though one of ordinary skill will recognize that the command could be received through various different user input devices as well as through various different GUI constructs. Furthermore, as stated above, in some embodiments the only type of collection that a user could create by request is a journal. 
     The process  700  next identifies (at  710 ) the presently selected images. In some embodiments, a user can select a subset of the images in a particular collection, and then instruct the application to create a new collection from the selected images. 
     The process then associates (at  715 ) the identified images as a new collection. In  FIG. 6 , three images are shown as presently selected, and thus these three images will be associated as a new collection. In some embodiments, the application creates a new collection data structure for the newly generated collection, and stores references (e.g., pointers, database reference IDs, etc.) to each of the images in the collection. 
       FIG. 8  conceptually illustrates a collection data structure  800  of some embodiments. When a user generates a new album or imports new images for a new event, the application automatically creates a new collection data structure for the album or event. The collection data structure  800  includes a collection ID, a collection type, a collection name, a key image, and references to a set of images. The collection ID is a unique identifier for the collection that the application uses when referencing the collection. The collection type is the type of collection (e.g., album, event, journal, etc.). In some embodiments, the application includes the “photos” collection, which references each image imported into the application irrespective of which other collections also include the image. The collection name is the user-assigned name for the collection, which is displayed at the top of the image viewing and editing GUI when the collection is selected as well as the name used for the collection&#39;s icon in the collection organization GUI. 
     The key image is an image set by the user to represent the collection. In some embodiments, the application displays the key image as the selectable icon for the collection on the glass shelf in the collection organization GUI. In addition, the collection data structure  800  includes an ordered series of references to each image in the collection. The order of the images determines the order in which the thumbnails are displayed within the thumbnail display area in some embodiments. As will be described below, some embodiments store data structures for each image imported into the application, and the collections reference these data structures. These references may be pointers, references to database entries, etc. 
       FIG. 9  illustrates navigation between the image organization, viewing, and editing GUI  650  (referred to in some places below as an image viewing GUI, image editing GUI, etc.) and the collection organization GUI  600  over four stages  910 - 940 . As shown, in the first stage  910 , the user selects a back button  905 . In some embodiments, this button causes the application to transition back to the collection organization GUI  600 . In some embodiments, the application animates this transition by minimizing the image viewing GUI  650  so that it shrinks into the collection icon of the collection that had been displayed. Stages  920 - 940  illustrate this animation. 
     In the second stage  920 , the image viewing GUI  650  has begun to shrink, so that the edges of the collection organization GUI  600  are visible. As shown, the application does not necessarily minimize the image viewing GUI  650  towards the center, but instead towards the location of the icon that represents the collection displayed in the GUI. The third stage  930  shows the application display at a point at which the image viewing GUI is barely larger than the collection icon  625 . Finally, at the fourth stage  940 , the image viewing GUI has fully minimized and only the collection display area is shown. While this figure illustrates the entire GUI  650  (i.e., the thumbnail display area, toolbars, and image display area) minimizing, some embodiments remove the thumbnail display area and toolbars from the display as soon as the user hits the back button, so that only the image display area is shown being minimized. 
       FIG. 10  illustrates a user navigating within the collection organization GUI  600  to view the newly created album, over four stages  1010 - 1040 . Within the collection organization GUI  600 , users can use the tabs  605  to choose between the albums, photos, events, and journals. As described below, users can also use swipe gestures to navigate between the different tabs. The first stage  1010  illustrates a selection of the albums tab  1005  while the events tab  1015  is active. As shown, some embodiments highlight the selected tab during the selection (e.g., while a finger is pressing down over the tab, while a mouse button is held down with a cursor over the tab, etc.). 
     The second stage  1020  illustrates that the albums tab  1005  is now active. In some embodiments, the application animates the transition between the different tabs (i.e., shows the events sliding out of the GUI while new shelves with the albums slide into the display). The shelves for the albums only include an icon  1025  that represents “Album 1”. At this stage, the user selects the icon  1025  in order to access this album. In some embodiments, this causes a transition to the image viewing GUI  650 . 
     As shown in stage  1030 , the application of some embodiments animates this transition as the opposite of the minimization animation shown in  FIG. 9 . Thus, at stage  1030 , the image viewing GUI  650  has begun to expand out of the selected icon  1025 . The fourth stage  1040  illustrates the result of this selection with the application displaying the image viewing GUI  650 . The GUI indicates at the top that the currently active collection is “Album 1”. In the thumbnail display area, the only thumbnails are those for the three images that were shown as selected for “Album 1” in  FIG. 6 . Some embodiments do not initially display any of the images in the image display area, instead waiting for a user to select one or more images. Other embodiments, however, initially select the first image in the ordered series for the collection or the key image for the collection. Yet other embodiments store persistent data for each collection that indicates which image or images were selected the last time the collection was opened on the device, and use this persistent data to display the collection upon its selection. 
       FIG. 11  illustrates a user navigating through the collection organization GUI  600  over four stages  1110 - 1140  according to some embodiments. As shown in the first stage  1110 , the application stores information on at least nine albums, including a Favorites album, a Camera Roll album, a Flagged photos album, as well as other albums. In some embodiments, users can tag an image as a favorite or flagged, which automatically places the image in the corresponding album. In addition, some embodiments automatically add to the Camera Roll album any image captured with the device on which the application operates. 
     In some embodiments, a swipe gesture causes the application to navigate between the tabs.  FIG. 11  illustrates such a gesture. As shown, in the first stage  1110  the user contacts the touchscreen with two fingers. In the next stage  1120 , the user moves the two fingers leftwards while maintaining contact with the touchscreen. As shown, the shelves  1105  begin moving to the left, as a second set of shelves  1115  approaches from the right side of the GUI. In the third stage  1130 , the user has released the point of contact with the touchscreen after sliding her fingers at least a threshold distance to qualify as a swipe gesture. In addition, the new set of shelves  1115  have continued moving to the left, replacing the shelves  1105 , as shown by the arrows. 
     The fourth stage  1140  illustrates that the shelves  1115  have fully moved into the GUI  600 . Furthermore, the photos tab  1125  is now highlighted in the display. Using these swipe gestures, the user can easily navigate between the different tabs without being required to specifically select the tab. When the user navigates to the photos tab, some embodiments display a similar set of shelves as for the other tabs, but display individual image thumbnails instead of collections. These shelves include a thumbnail for each image imported into the image viewing application, which enable the user to navigate directly to a specific image (e.g., to edit the image, share the image, etc.). 
     Although the shelves  1105  are entirely filled in the first stage  1110  of  FIG. 11 , a particular instance of the application might store more than the maximum number of collections that can be shown on the device at once. As such, the application of some embodiments enables users to scroll through the shelves vertically.  FIG. 12  illustrates such a scrolling technique according to some embodiments over two stages  1210  and  1220  of the GUI  600 . 
     In stage  1210 , the user contacts the touchscreen with two fingers. In the next stage  1220 , the user moves the two fingers upwards while maintaining contact with the touchscreen. This causes the shelves to slide upwards through the GUI  600 . As a result, an additional shelf has appeared at the bottom of the GUI  600  and the top shelf has disappeared. As this is a smooth scrolling technique, in some embodiments the shelves do not move discretely, but instead may scroll partially on or off the top and bottom of the display depending on the distance of the user&#39;s swiping gesture. 
     The image-viewing application of some embodiments allows users to create an essentially unlimited number of albums, so long as the storage capacity is available on the device. Similarly, users can have an unlimited number of events, photos, or journals. One of ordinary skill in the art will recognize that other gestures and inputs may be used to navigate between sets of shelves. For example, some embodiments include an unlimited number of shelves stacked vertically, so that swiping upwards scrolls continuously through the shelves. In addition, some embodiments respond to tap or click inputs on the left and right sides of the screen as an alternative to or in conjunction with the swipe inputs. 
     The image viewing, editing, and organization application of some embodiments operates on a mobile device. Some embodiments operate on a tablet device (e.g., an iPad®), while other embodiments operate on a mobile phone (e.g., an iPhone®) or a media player (e.g., an iPod®). The GUI of the tablet implementation of some embodiments is different from the GUI of the mobile phone/media player implementation of some embodiments, though other embodiments of the tablet implementation may use the mobile phone/media player GUI, and vice versa. 
       FIG. 13  illustrates the navigation between the image viewing and editing GUI  1350  and the collection organization GUI  1300  over four stages  1310 - 1340  for the mobile phone and media player implementation of some embodiments while in portrait mode. The first stage  1310  illustrates the image viewing and editing GUI  1350 , which includes many of the same features as the image viewing and editing GUI  650 . This GUI will be described in greater detail below. In this stage, a user selects the back button  1305 , in order to navigate back to the collection organization GUI. 
     The second stage  1320  illustrates the collection organization GUI  1300  of some embodiments. Like the GUI  600 , this GUI displays a set of shelves (e.g., glass shelves) with icons that represent the different collections. However, whereas the GUI  600  included a set of tabs for the different types of collections, the GUI  700  includes a set of selectable icons  1315  at the bottom of the display. These icons include selections for albums (currently selected), photos, events, and journals. In addition, the display includes a settings menu. 
     At this stage  1320 , the user selects the events icon  1325 . The third stage  1325  illustrates that the events icon  1325  is now selected, and icons for different collections (two events) are shown on the shelves. The user selects one of these events, and the fourth stage  1340  illustrates the image viewing GUI  1350  for the selected collection as a result. 
     II. Image Viewing 
     The above-described figures illustrated various examples of the image viewing GUI of some embodiments.  FIG. 14  illustrates a detailed view of a GUI  1400  of some embodiments for viewing, editing, and organizing images. The GUI  1400  will be described in part by reference to  FIG. 15 , which conceptually illustrates a data structure  1500  for an image as stored by the application of some embodiments. 
     The data structure  1500  includes an image ID  1505 , image data  1510 , edit instructions  1515 , Exchangeable image file format (Exif) data  1525 , a caption  1530 , shared image data  1535 , cached versions  1540  of the image, any tags  1545  on the image, and any additional data  1550  for the image. The image ID  1505  is a unique identifier for the image, which in some embodiments is used by the collection data structures to refer to the images stored in the collection. 
     The image data  1510  is the actual full-size pixel data for displaying the image (e.g., a series of color-space channel values for each pixel in the image or an encoded version thereof). In some embodiments, this data may be stored in a database of the image viewing, editing, and organization application, or may be stored with the data of another application on the same device. Thus, the data structure may store a pointer to the local file associated with the application or an ID that can be used to query the database of another application. In some embodiments, once the application uses the image in a journal or makes an edit to the image, the application automatically makes a local copy of the image file that contains the image data. 
     The edit instructions  1515  include information regarding any edits the user has applied to the image. In this manner, the application stores the image in a non-destructive format, such that the application can easily revert from an edited version of the image to the original at any time. For instance, the user can apply a saturation effect to the image, leave the application, and then reopen the application and remove the effect at another time. The edits stored in these instructions may be crops and rotations, full-image exposure and color adjustments, localized adjustments, and special effects, as well as other edits that affect the pixels of the image. Some embodiments store these editing instructions in a particular order, so that users can view different versions of the image with only certain sets of edits applied. 
     The Exif data  1525  includes various information stored by the camera that captured the image, when that information is available. While Exif is one particular file format that is commonly used by digital cameras, one of ordinary skill in the art will recognize that comparable information may be available in other formats as well, or may even be directly input by a user. The Exif data  1525  includes camera settings data, GPS data, and a timestamp. The camera settings data includes information about the camera settings for a image, if that information is available from the camera that captured the image. This information, for example, might include the aperture, focal length, shutter speed, exposure compensation, and ISO. The GPS data  1525  indicates the location at which an image was captured, while the timestamp indicates the time (according to the camera&#39;s clock) at which the image was captured. 
     The caption  1530  is a user-entered description of the image. In some embodiments, this information is displayed with the image in the image viewing area, but may also be used to display over the image in a created journal, and may be used if the image is posted to a social media or photo-sharing website. When the user posts the image to such a website, the application generates shared image data  1535  for the image. This information stores the location (e.g., Facebook®, Flickr®, etc.), as well as an object ID for accessing the image in the website&#39;s database. The last access date is a date and time at which the application last used the object ID to access any user comments on the image from the social media or photo sharing website. 
     The cached image versions  1540  store versions of the image that are commonly accessed and displayed, so that the application does not need to repeatedly generate these images from the full-size image data  1510 . For instance, the application will often store a thumbnail for the image as well as a display resolution version (e.g., a version tailored for the image display area). The application of some embodiments generates a new thumbnail for an image each time an edit is applied, replacing the previous thumbnail. Some embodiments store multiple display resolution versions including the original image and one or more edited versions of the image. 
     The tags  1545  are information that the application enables the user to associate with an image. For instance, in some embodiments, users can mark the image as a favorite, flag the image (e.g., for further review), and hide the image so that the image will not be displayed within the standard thumbnail grid for a collection and will not be displayed in the image display area when the user cycles through a collection that includes the image. Other embodiments may include additional tags. Finally, the image data structure  1500  includes additional data  1550  that the application might store with an image (e.g., locations and sizes of faces, etc.). 
     One of ordinary skill in the art will recognize that the image data structure  1500  is only one possible data structure that the application might use to store the required information for an image. For example, different embodiments might store additional or less information, store the information in a different order, etc. 
     Returning to  FIG. 14 , the GUI  1400  includes a thumbnail display area  1405 , an image display area  1410 , a first toolbar  1415 , a second toolbar  1420 , and a third toolbar  1425 . The thumbnail display area  1405  displays thumbnails of the images in a selected collection. Thumbnails are small representations of a full-size image, and represent only a portion of an image in some embodiments. For example, the thumbnails in thumbnail display area  1405  are all squares, irrespective of the aspect ratio of the full-size images. In order to determine the portion of a rectangular image to use for a thumbnail, the application identifies the smaller dimension of the image and uses the center portion of the image in the longer direction. For instance, with a 1600×1200 pixel image, the application would use a 1200×1200 square. To further refine the selected portion for a thumbnail, some embodiments identify a center of all the faces in the image (using a face detection algorithm), then use this location to center the thumbnail portion in the clipped direction. Thus, if the faces in the theoretical 1600×1200 image were all located on the left side of the image, the application would use the leftmost 1200 columns of pixels rather than cut off 200 columns on either side. 
     After determining the portion of the image to use for the thumbnail, the image-viewing application generates a low resolution version (e.g., using pixel blending and other techniques) of the image. The application of some embodiments stores the thumbnail for an image as a cached version  1540  of the image. Thus, when a user selects a collection, the application identifies all of the images in the collection (through the collection data structure), and accesses the cached thumbnails in each image data structure for display in the thumbnail display area. 
     The user may select one or more images in the thumbnail display area (e.g., through various touch interactions described in Section IV below). The selected thumbnails are displayed with a highlight or other indicator of selection. In thumbnail display area  1405 , the thumbnail  1430  is selected. In addition, as shown, the thumbnail display area  1405  of some embodiments indicates a number of images in the collection that have been flagged (i.e., that have a tag  1545  for the flag set to yes). In some embodiments, this text is selectable in order to display only the thumbnails of the flagged images. 
     The application displays selected images in the image display area  1410  at a larger resolution than the corresponding thumbnails. The images are not typically displayed at the full size of the image, as images often have a higher resolution than the display device. As such, the application of some embodiments stores a cached version  1540  of the image designed to fit into the image display area. Images in the image display area  1410  are displayed in the aspect ratio of the full-size image. When one image is selected, the application displays the image as large as possible within the image display area without cutting off any part of the image. When multiple images are selected, the application displays the images in such a way as to maintain their visual weighting by using approximately the same number of pixels for each image, even when the images have different aspect ratios. 
     The first toolbar  1415  displays title information (e.g., the name of the collection shown in the GUI, a caption that a user has added to the currently selected image, etc.). In addition, the toolbar  1415  includes a first set of GUI items  1435 - 1438  and a second set of GUI items  1440 - 1443 . 
     The first set of GUI items includes a back button  1435 , a grid button  1436 , a help button  1437 , and an undo button  1438 . The back button  1435  enables the user to navigate back to the collection organization GUI, as shown above in  FIG. 9 . Selection of the grid button  1436  causes the application to move the thumbnail display area on or off of the GUI (e.g., via a slide animation). In some embodiments, users can also slide the thumbnail display area on or off of the GUI via a swipe gesture. The help button  1437  activates a context-sensitive help feature that identifies a current set of tools active for the user and provides help indicators for those tools that succinctly describe the tools to the user. In some embodiments, the help indicators are selectable to access additional information about the tools. Selection of the undo button  1438  causes the application to remove the most recent edit to the image, whether this edit is a crop, color adjustment, etc. In order to perform this undo, some embodiments remove the most recent instruction from the set of edit instructions  1515  stored with the image. 
     The second set of GUI items includes a sharing button  1440 , an information button  1441 , a show original button  1442 , and an edit button  1443 . The sharing button  1440  enables a user to share an image in a variety of different ways. In some embodiments, the user can send a selected image to another compatible device on the same network (e.g., Wi-Fi or Bluetooth network), upload an image to an image hosting or social media website, and create a journal (i.e., a presentation of arranged images to which additional content can be added) from a set of selected images, among others. 
     The information button  1441  activates a display area that displays additional information about one or more selected images. The information displayed in the activated display area may include some or all of the Exif data  1525  stored for an image (e.g., camera settings, timestamp, etc.). When multiple images are selected, some embodiments only display Exif data that is common to all of the selected images. Some embodiments include additional tabs within the information display area for (i) displaying a map showing where the image or images were captured according to the GPS data, if this information is available and (ii) displaying comment streams for the image on any photo sharing websites. To download this information from the websites, the application uses the object ID stored for the image with the shared image data  1535  and sends this information to the website. The comment stream and, in some cases, additional information, are received from the website and displayed to the user. 
     The show original button  1442  enables the user to toggle between the original version of an image and the current edited version of the image. When a user selects the button, the application displays the original version of the image without any of the editing instructions  1515  applied. In some embodiments, the appropriate size image is stored as one of the cached versions  1540  of the image, making it quickly accessible. When the user selects the button  1442  again, the application displays the edited version of the image, with the editing instructions  1515  applied. 
     The edit button  1443  allows the user to enter or exit edit mode. When a user has selected one of the sets of editing tools in the toolbar  1420 , the edit button  1443  returns the user to the viewing and organization mode, as shown in  FIG. 14 . When the user selects the edit button  1443  while in the viewing mode, the application returns to the last used set of editing tools in the order shown in toolbar  1420 . That is, the items in the toolbar  1420  are arranged in a particular order, and the edit button  1443  activates the rightmost of those items for which edits have been made to the selected image. 
     The toolbar  1420 , as mentioned, includes five items  1445 - 1449 , arranged in a particular order from left to right. The crop item  1445  activates a cropping and rotation tool that allows the user to align crooked images and remove unwanted portions of an image. The exposure item  1446  activates a set of exposure tools that allow the user to modify the black point, shadows, contrast, brightness, highlights, and white point of an image. In some embodiments, the set of exposure tools is a set of sliders that work together in different combinations to modify the tonal attributes of an image. The color item  1447  activates a set of color tools that enable the user to modify the saturation and vibrancy, as well as color-specific saturations (e.g., blue pixels or green pixels) and white balance. In some embodiments, some of these tools are presented as a set of sliders. The brushes item  1448  activates a set of enhancement tools that enable a user to localize modifications to the image. With the brushes, the user can remove red-eye and blemishes, and apply or remove saturation and other features to localized portions of an image by performing a rubbing action over the image. Finally, the effects item  1449  activates a set of special effects that the user can apply to the image. These effects include gradients, tilt shifts, non-photorealistic desaturation effects, grayscale effects, various filters, etc. In some embodiments, the application presents these effects as a set of items that fan out from the toolbar  1425 . 
     As stated, the UI items  1445 - 1449  are arranged in a particular order. This order follows the order in which users most commonly apply the five different types of edits. Accordingly, the editing instructions  1515  are stored in this same order, in some embodiments. When a user selects one of the items  1445 - 1449 , some embodiments apply only the edits from the tools to the left of the selected tool to the displayed image (though other edits remain stored within the instruction set  1515 ). 
     The toolbar  1425  includes a set of GUI items  1450 - 1454  as well as a settings item  1455 . The auto-enhance item  1450  automatically performs enhancement edits to an image (e.g., removing apparent red-eye, balancing color, etc.). The rotation button  1451  rotates any selected images. In some embodiments, each time the rotation button is pressed, the image rotates 90 degrees in a particular direction. The auto-enhancement, in some embodiments, comprises a predetermined set of edit instructions that are placed in the instruction set  1515 . Some embodiments perform an analysis of the image and then define a set of instructions based on the analysis. For instance, the auto-enhance tool will attempt to detect red-eye in the image, but if no red-eye is detected then no instructions will be generated to correct it. Similarly, automatic color balancing will be based on an analysis of the image. The rotations generated by the rotation button are also stored as edit instructions. 
     The flag button  1452  tags any selected image as flagged. In some embodiments, the flagged images of a collection can be displayed without any of the unflagged images. The favorites button  1453  allows a user to mark any selected images as favorites. In some embodiments, this tags the image as a favorite and also adds the image to a collection of favorite images. The hide button  1454  enables a user to tag an image as hidden. In some embodiments, a hidden image will not be displayed in the thumbnail display area and/or will not be displayed when a user cycles through the images of a collection in the image display area. As shown in  FIG. 15 , many of these features are stored as tags in the image data structure. 
     Finally, the settings button  1455  activates a context-sensitive menu that provides different menu options depending on the currently active toolset. For instance, in viewing mode the menu of some embodiments provides options for creating a new album, setting a key image for an album, copying settings from one image to another, and other options. When different sets of editing tools are active, the menu provides options related to the particular active toolset. 
     One of ordinary skill in the art will recognize that the image viewing and editing GUI  1400  is only one example of many possible graphical user interfaces for an image viewing, editing, and organizing application. For instance, the various items could be located in different areas or in a different order, and some embodiments might include items with additional or different functionalities. The thumbnail display area of some embodiments might display thumbnails that match the aspect ratio of their corresponding full-size images, etc. 
     III. Interaction in Different GUI Modes 
       FIG. 14 , above, illustrated a particular graphical user interface  1400  of an image viewing, editing, and organization application. In some embodiments, the application provides multiple GUI modes, of which the GUI  1400  is only one. These modes may differentiate between portrait and landscape orientations, between left- and right-handed users, or other factors. Some embodiments have three different modes—portrait, left-handed landscape, and right-handed landscape. These modes present the same GUI items and display areas to the user, but arranged in different manners. 
     A. Left and Right Handed GUI 
     Some embodiments provide both a left-handed GUI and a right-handed GUI, between which users can switch. The different options may be presented in both portrait and landscape modes, or only in landscape. In some embodiments, to switch between the left-handed GUI and the right-handed GUI, the user moves a specific GUI item (e.g., the thumbnail display area) within the GUI. As a result of moving the specific GUI item from a first position to a second position, the application switches from providing the right-handed GUI to providing the left-handed GUI, or vice versa. The differences between the two GUIs, in some embodiments, are not only the location of the specific GUI item, but also the location and order (e.g., left to right order) of additional sets of GUI items. 
       FIG. 16  illustrates a GUI  1600  over four stages  1610 - 1640  in which the user moves a thumbnail display area  1605  from the left side to the right side of the GUI in order to switch from right-handed mode to left-handed mode. The GUI  1600  includes the thumbnail display area  1605 , an image display area  1615 , a first set of GUI items  1625  (the grid on/off, help, and undo buttons), a back button  1635 , a second set of GUI items  1645  (the share, info, and toggle original buttons), an edit button  1650 , a third set of GUI items  1655  (the edit tool activation buttons), and a settings menu button  1660   
     The first stage  1610  illustrates the GUI  1600  in right-handed mode. In the right-handed mode, the thumbnail display area  1605  is situated on the left-side of the GUI. The back button  1635  and the first set of GUI items  1625  are situated on the left of the upper toolbar, the edit button  1650  and the second set of GUI items  1655  are situated on the right of the upper toolbar, the third set of GUI items  1655  are situated at the bottom left (below the thumbnail display area), and the settings menu button is situated at the bottom right. This stage additionally shows that a user has placed a finger over the thumbnail display area in order to perform a touch gesture on the display area. In some embodiments, the thumbnail display area includes a header area that can be selected in order to move the display area. 
     The second stage  1620  illustrates that the user is in the midst of executing a drag (or swipe) gesture with one finger. To perform such a gesture, the user presses the finger down over the thumbnail display area and slides the finger along the touchscreen to the right, without releasing contact. As the user moves her fingers over the touchscreen, the application moves the thumbnail display area  1605  along with the finger. 
     The third stage  1630  illustrates that the user has moved the touchscreen further to the right along the touchscreen. In addition, this figure shows that as the user releases contact with the screen, the thumbnail display area  1605  snaps to the right edge of the GUI  1600 . In some embodiments, when the user releases contact with the display area on the left side of the GUI, the thumbnail display area automatically snaps back to that side, and the same for the right side. 
     The fourth stage  1640  illustrates the GUI  1600  in left-handed mode after the user has released the thumbnail display area. In the left-handed mode, most of the GUI tools have switched sides. The settings menu button  1660  is now situated in the bottom left, while the third set of GUI items  1655  is situated in the bottom right. The third set of GUI items  1655  maintain their left to right order, from the crop activation button to the effects activation button. These items are arranged in the typical order in which the user will make edits to an image (cropping and rotating the image first, next adjusting exposure and color, then using the brushes for touchups, and finally applying any special effects to the image). As such, these tools are arranged in the same order in both GUI modes. 
     The sets of tools in the upper toolbar, however, switch places and reverse order. The back button  1635  and the edit button  1650  are fixed (except in that the entire toolbar slides to the left to accommodate the thumbnail display area  1605 ) as the leftmost and rightmost buttons, respectively. However, the first set of GUI items  1625  and the second set of GUI items  1645  switch locations and reverse their order. The first set of GUI items  1625  is now situated next to the edit button  1650 , though in the opposite left to right order. Similarly, the second set of GUI items  1645  is now located next to the back button  1635 , also in the opposite left to right order. These items that are not arranged in a particular order thereby maintain their relative positions to the thumbnail display area  1605 . 
     In some embodiments, the GUI also includes the auto-enhance, rotation, flag, favorite, and hide buttons, as illustrated in  FIG. 14 . In some such embodiments, these GUI items remain in the bottom center of the GUI when in left-handed mode and stay in the same order. In other embodiments, however, the auto-enhance button is on the right side of this set of items while the hide button is on the left side in left-handed mode. 
     While this figure illustrates the user making the drag gesture with the left hand in order to switch to the left-handed GUI, some embodiments allow the user to drag the thumbnail display area in either direction with a finger of either hand (or with a different gesture, such as a two-finger drag, a swipe, etc.). In this sense, the GUIs are not responsive to which hand the user actually uses, but rather to the location of the thumbnail display area. On the other hand, the application of some embodiments can recognize which hand the user is using (e.g., based on the relative positions of different contacts of the touchscreen) and switch the display accordingly. Other embodiments can differentiate between hands for certain gestures (e.g., a simultaneous touch of all five fingers to the center of the screen) and use these gestures as commands to switch from one mode to the other. 
     In addition to having left- and right-handed GUI modes, some embodiments display the image viewing and editing GUI differently in portrait and landscape modes. In some embodiments, the thumbnail display area is located in a different area of the display when in portrait mode as compared to either left-handed or right-handed landscape mode. For example, in some embodiments the application displays the thumbnail display area at the bottom of the portrait GUI. 
     Some embodiments determine the location of the various GUI items in portrait mode based on the most recently used landscape mode for the application. For example, some embodiments operate on devices with a built-in accelerometer or gyroscope that identifies whether the device is oriented upright or sideways, and provides this information through the operating system to the applications. When the user reorients the device to portrait mode, some embodiments align the GUI elements of the image-viewing application based on the landscape mode to which the GUI was set before the reorientation. 
       FIGS. 17-19  illustrate left-handed and right-handed GUI modes of some embodiments, in both portrait and landscape mode. Rather than illustrating the GUI implementation of some embodiments shown in  FIG. 14  and other figures above, these figures illustrate an image viewing and editing GUI  1700  used for the mobile phone and media player implementation of some embodiments. 
       FIG. 17  illustrates the GUI  1700  over three stages  1710 - 1730  as a device on which the image viewing application operates is rotated from portrait mode to landscape mode. As shown in  FIG. 17 , the GUI  1700  includes a thumbnail display area  1705 , an image display area  1715 , a first toolbar  1725  (located at the bottom of the GUI), and a second toolbar  1727  (located at the top of the GUI). 
     The first toolbar  1725  includes an auto-enhance button  1730 , a rotation button  1735 , a flag button  1740 , a favorites button  1745 , a hide button  1750 , a settings button  1755 , and a toolbox button  1760 . The various GUI items  1730 - 1755  operate in the same manner as described above by reference to  FIG. 14 . The toolbox  1760  of some embodiments allows a user to access various different sets of editing tools. In some embodiments, when a user selects the toolbox  1760 , the items  1730 - 1750  disappear and are replaced by GUI items similar to the items  1445 - 1449  (a crop item, exposure item, color item, brushes item, and effects item). 
     The second toolbar  1727  includes a back button  1765 , a grid button  1770 , a show original button  1780 , a share button  1785 , and an edit button  1790 . These GUI items also operate in the same manner as described above by reference to  FIG. 14 . In some embodiments, the help feature and undo feature can be accessed through the settings item  1755  rather than having separate items. 
     The first stage  1710  of  FIG. 17  illustrates the GUI  1700  in portrait mode, with the device on which the application operates held in an upright position. In the second stage  1720 , the user has begun to turn the device sideways. Not until the third stage  1730 , when the device has been rotated a full 90 degrees, does the application switch from displaying the GUI in portrait mode to landscape mode. In some embodiments, the device contains an accelerometer or gyroscope, from which the operating system of the device determines whether the device should be in portrait or landscape mode. This determination is passed to the application, which outputs the appropriate GUI. 
     The third stage  1730  illustrates the landscape mode GUI  1700  of some embodiments. The GUI includes the same set of UI items in the upper and lower toolbars, although the items are more spread out. In addition, the thumbnail display area  1705  is on the left rather than the bottom of the display. In this case, the portrait mode GUI was in right-hand mode (i.e., in stages  1710  and  1720 ), and therefore when the application switches to landscape, it uses the right-hand landscape mode for the GUI  1700 . 
       FIG. 18  illustrates the GUI  1700  over four stages  1810 - 1840  in which the user moves the thumbnail display area  1705  from the left side of the GUI to the right side of the GUI in order to switch from right-handed mode to left-handed mode. The touch gesture used to drag the thumbnail display area  1705  over the first three stages  1810 - 1830  is a similar gesture to that shown above in  FIG. 16 . The fourth stage  1840  illustrates the GUI  1700  in left-handed mode, with the thumbnail display area  1705  on the right side of the GUI. In this implementation, the application reverses the order of GUI items  1730 - 1760  in the toolbar  1725 , with the toolbox icon  1760  now on the right and the settings icon  1755  on the left, and the auto-enhance, rotate, flag, favorites, and hide items also reversed. 
       FIG. 19  illustrates the GUI  1700  over three stages  1910 - 1930  as the user rotates the device on which the application operates back to portrait mode. In this case, however, the application is operating in left-handed mode while in landscape mode. As a result, at stage  1930 , the GUI items in the toolbar  1725  are reversed as compared to the right-hand portrait mode shown in  FIG. 17 . 
     B. Interactions with Thumbnail Display Area 
     In either left- or right-handed mode, the image viewing application enables various interactions with the thumbnail display area (also referred to below as the thumbnail grid). Users can change the size of the thumbnail display area, change the number of columns of thumbnails, and scroll through the thumbnails.  FIG. 20  conceptually illustrates a state diagram  2000  showing states and changes in the state for the thumbnail display area in the image viewing GUI of some embodiments. One of ordinary skill will recognize that this state diagram does not cover every possible interaction with the thumbnail display area. For instance, the state diagram does not cover scrolling through the thumbnails or the selection of thumbnails. Furthermore, although the state diagram indicates different states for left- and right-handed GUI modes, the equivalents of states that are shown for one mode are omitted for the other mode in the interest of simplicity. The state diagram  2000  will be described by reference to  FIGS. 21-28 , which illustrate various interactions with the GUI  1600  in both left- and right-handed mode. 
     When the user is not interacting with the GUI, it will be in either state  2005  (right-handed mode with the thumbnail grid on the left side of the GUI) or in state  2050  (left-handed mode with the thumbnail grid on the right side of the GUI). As shown in the above  FIG. 16 , the user can cause a transition from state  2005  to state  2050  by dragging the thumbnail grid from the left side of the GUI to the right side of the GUI. Conversely, when the user drags the thumbnail grid from the right side of the GUI to the left side, the GUI transitions from state  2050  to state  2005 . 
     The user can increase and decrease the width and/or number of columns of the thumbnail grid in some embodiments by dragging the boundary (or seam) between the thumbnail grid and the image display area. The state diagram  2000  illustrates the states describing such input events when the GUI is in right-handed mode (state  2005 ), but one of ordinary skill in the art will recognize that the opposite directions of movement will apply to otherwise equivalent states when in left-handed mode (state  2050 ). In some embodiments, the thumbnail grid has a default width of two columns when the application is initialized. 
     While in state  2005 , when the user selects the boundary between the thumbnail grid and the image display area and moves to the right, the GUI transitions to state  2010  to display a progressively wider thumbnail grid. In some embodiments, the user selects the boundary by placing a single finger on the touchscreen over the boundary (i.e., so that the contact area includes both part of the thumbnail grid and part of the image display area). So long as the user continues moving her finger to the right, the thumbnail grid keeps widening. If the user releases the boundary (e.g., by removing her finger from the touchscreen), then the GUI returns to state  2005 . 
     When the user has moved the boundary a threshold distance, the application transitions to state  2015  to add a column of thumbnails. This causes a rearrangement of the thumbnails in the thumbnail grid. The application of some embodiments orders the thumbnails (when the grid has two columns) with the first two on the top row, the next two on the second row, etc. When the number of columns expands to three, the first thumbnail from the second row moves up to the top row, both of the thumbnails from the third row move to the second row, etc. 
       FIG. 21  illustrates a user increasing the size of the thumbnail display area over four stages  2110 - 2140  of GUI  1600 . As shown, in the first stage  2110 , the user places a finger over the boundary between the thumbnail display area  1605  and the image display area  1615 . In some embodiments, the application does not actually draw a boundary line, or seam, but instead the boundary is simply visible as a result of the change in color between the thumbnail display area and the image display area. For clarity&#39;s sake, however, these figures illustrate such a boundary. 
     In the second and third stages  2120  and  2130 , the user drags the boundary to the right. At the fourth stage  2140 , the boundary has been moved far enough for the thumbnails to rearrange into a third column. As shown, the thumbnail  2105  of the clouds moves up to the top row, and the other thumbnails rearrange as well. This figure illustrates (as does the state diagram  2000 ) the thumbnail display area  1605  expanding (and the image display area correspondingly shrinking) before the third column is created. However, some embodiments move the boundary only in discrete amounts—i.e., once the user&#39;s finger has moved the threshold distance over the screen, the application automatically changes the width of the thumbnail display area from a two-column width to a three-column width. That is, as the user moves her finger away from the boundary, the GUI remains static until a threshold movement has been reached, at which point the thumbnail display area dynamically rearranges to add another column as the boundary moves by a fixed amount to the right, thereby reducing the size of the image display area. 
     Returning to the state diagram  2000 , after adding the column of thumbnails, the GUI transitions either back to state  2010  if the touch movement continues and the thumbnail grid has not reached the maximum size, or to state  2020  if the maximum number of columns has been reached. When the maximum number of columns is reached, the application stops allowing the expansion of the grid area (at state  2020 ). In some embodiments, the application only allows the thumbnail display area to have one, two, or three columns of thumbnails; other embodiments (e.g., those on smaller devices) only allow one or two columns. At any of these three states, if the user releases the boundary (i.e., by removing the touch input), the application transitions back to state  2005 . 
     Similar state changes occur when the user drags the boundary between the thumbnail display area and the image display area towards the edge of the screen. Again, these state changes are shown in  FIG. 20  for when the GUI is in right-handed mode, but are equally applicable to the GUI in left-handed mode (with the movement in the opposite direction). 
     While in state  2005 , when the user selects the boundary between the thumbnail grid and the image display area and moves to the left, the GUI transitions to state  2010  to display a progressively narrower thumbnail grid. In some embodiments, the user selects the boundary by placing a single finger on the touchscreen over the boundary (i.e., so that the contact area includes both part of the thumbnail grid and part of the image display area). So long as the user continues moving her finger to the left, the thumbnail grid keeps narrowing. If the user releases the boundary (e.g., by removing her finger from the touchscreen), then the GUI returns to state  2005 . 
     When the user has moved the boundary a threshold distance, the application transitions to state  2030  to remove a column of thumbnails. This causes a rearrangement of the thumbnails in the thumbnail grid. The application of some embodiments orders the thumbnails (when the grid has two columns) with the first two on the top row, the next two on the second row, etc. When the number of columns is reduced to one, the second thumbnail from the top row moves to the second row, the first thumbnail in the second row moves to the third row, etc. 
       FIG. 22  illustrates a user decreasing the size of the thumbnail display area over four stages  2210 - 2240  of GUI  1600 . As shown, in the first stage  2210 , the user places a finger over the boundary between the thumbnail display area  1605  and the image display area  1615 . In some embodiments, the application does not actually draw a boundary line, or seam, but instead the boundary is simply visible as a result of the change in color between the thumbnail display area and the image display area. For clarity&#39;s sake, however, these figures illustrate such a boundary. 
     In the second stage  2220 , the user has started dragging the boundary to the left. In this figure, once the boundary begins to encroach on the second column, the application rearranges the thumbnails into a single column. As shown, the thumbnail  2205  of the kayak moves down to the second row, and the other thumbnails rearrange as well. In the third stage  2230 , the user continues to drag the boundary to the left. Finally, at the fourth stage  2240 , the thumbnail display area  1605  has reached its minimum width and cannot keep shrinking. This figure (and the state diagram  2000 ) illustrates the thumbnail display area  1605  shrinking (and the image display area correspondingly decreasing) in a continuous manner. However, as with the increase in the thumbnail display area described above, some embodiments move the boundary only in discrete amounts—i.e., once the user&#39;s finger has moved the threshold distance over the screen, the application automatically changes the width of the thumbnail display area from a two-column width to a one-column width. 
     Returning to the state diagram  2000 , after removing the column of thumbnails, the GUI transitions either back to state  2025  if the touch movement continues and the thumbnail grid has not reached the maximum size, or to state  2035  if the maximum number of columns has been reached. When the maximum number of columns is reached, the application stops allowing the expansion of the grid area (at state  2020 ). In some embodiments, the application only allows the thumbnail display area to have one, two, or three columns of thumbnails; other embodiments (e.g., those on smaller devices) only allow one or two columns. At any of these three states, if the user releases the boundary (i.e., by removing the touch input), the application transitions back to state  2005 . In addition, from the expansion state  2010 , the GUI can transition to state  2025  (or vice versa) if the user reverses the direction of movement of the touch input over the boundary. 
     In addition to modifying the size and number of columns of the thumbnail display area, some embodiments allow the user to slide the thumbnail display area out of the GUI and back onto the GUI. This may be accomplished, in some embodiments, via a swipe gesture or the selection of GUI item, as well as other GUI interactions (e.g., a hotkey or set of hotkeys, selection of a menu option, etc.). The state diagram  2000  conceptually illustrates these interactions in the context of a left-handed GUI (with the thumbnail display area on the right side), but these interactions are equally applicable (with the directions reversed) to the right-handed GUI. 
     As shown, with the GUI in state  2050  (left-handed mode with the thumbnail grid displayed), when the user performs a rightwards swipe gesture over the grid, or selects the grid button UI item, the GUI transitions to state  2055  to slide the grid off the right side of the display. Once the grid has slid off the display, the GUI transitions to state  2060  to display the GUI in left-hand mode without the thumbnail grid. 
       FIG. 23  illustrates such a swipe gesture to remove the thumbnail display area  1605  from the GUI  1600  while in the right-handed GUI mode over four stages  2310 - 2340 . As shown, at the first stage  2310 , the user begins to contact the touchscreen over the thumbnail display area  1605  with one finger (though other swipe gestures with different numbers of points of contact, or other gestures altogether may be used). The second stage  2320  illustrates the user moving her finger to the left, causing the thumbnail display area to begin sliding in that direction. In the third stage  2330 , the user has released the swipe gesture as the thumbnail display area  1605  continues to slide out of the GUI to the left. The fourth stage  2340  illustrates that the thumbnail display area is no longer shown in the GUI, and the image display area  1615  has expanded. Based on the location of the various user interface tools, the user can easily tell that the GUI is still in right-handed mode. 
     In some embodiments, the application requires the user&#39;s finger to remain in contact with the touchscreen for a particular threshold distance and/or move at a threshold speed in order to qualify as a swipe gesture. However, in some embodiments this determination as to whether an input qualifies as a swipe gesture is made by the operating system of the device on which the image viewing application operates, rather than the application itself. The swipe gesture and location are passed from the operating system to the application, which then translates that swipe gesture into instructions to slide the thumbnail grid out of the GUI. 
       FIG. 24  illustrates a similar swipe gesture to remove the thumbnail display area  1605  from the GUI  1600  while in the left-handed mode over four stages  2410 - 2440 . These stages parallel the stages of  FIG. 23 . As shown, at the first stage  2410 , the user begins to contact the touchscreen over the thumbnail display area  1605  with one finger (though other swipe gestures with different numbers of points of contact, or other gestures altogether may be used). The second stage  2420  illustrates the user moving her finger to the right, causing the thumbnail display area to begin sliding in that direction. In the third stage  2430 , the user has released the swipe gesture as the thumbnail display area  1605  continues to slide out of the GUI to the right. The fourth stage  2440  illustrates that the thumbnail display area is no longer shown in the GUI, and the image display area  1615  has expanded. Based on the location of the various user interface tools, the user can easily tell that the GUI is still in left-handed mode. 
     As shown in  FIG. 20 , some embodiments also transition from state  2050  to state  2055  and then  2060  when a user selects a grid button that causes the thumbnail display area to slide on and off of the GUI.  FIG. 25  illustrates the selection of such a GUI item  2505  in the GUI  1600  over four stages  2510 - 2540 . As shown, in the first stage  2510 , the user taps the grid button  2505 . As with the swipe gestures, in some embodiments the operating system of the device translates the screen contact information into a tap gesture and a location and passes this information to the image-viewing application. The second stage  2520  and third stage  2530  illustrate the thumbnail display area  1605  sliding out of the GUI. The resultant GUI shown in stage  2540  is the same as the resultant GUI at the end of  FIG. 23 , with an expanded image display area  1615 . 
     With the GUI in state  2060  (the left-handed mode without the thumbnail grid), when the user either performs a leftward sweep gesture from the right edge of the GUI or selects the grid button UI item, the GUI transitions to state  2065  to slide the grid from the right side back onto the display. Once the grid has slid back onto the display, the GUI transitions back to state  2050  to display the GUI in left-handed mode with the thumbnail grid present. 
       FIG. 26  illustrates such a swipe gesture to return the thumbnail display area  1605  to the GUI  1600  while in the right-handed GUI mode over four stages  2610 - 2640 . As shown, at the first stage  2610 , the user begins to contact the touchscreen near the left edge of the GUI with one finger (though other swipe gestures with different numbers of points of contact, or other gestures altogether may be used). Different embodiments use different thresholds to determine how close the touch contact needs to be in order to be considered close to the edge for sliding the thumbnail display area back onto the GUI. The second stage  2620  illustrates the user moving her finger to the right, causing the thumbnail display area  1605  to begin sliding in that direction back onto the GUI. In the third stage  2630 , the user has released the swipe gesture as the thumbnail display area  1605  continues to slide onto the GUI to the right. The fourth stage  2640  illustrates that the thumbnail display area  1605  is fully present in the GUI, in the right-handed mode. 
       FIG. 27  illustrates a similar swipe gesture to return the thumbnail display area  1605  to the GUI  1600  while in the left-handed GUI mode over four stages  2710 - 2740 . As shown, at the first stage  2710 , the user begins to contact the touchscreen near the right edge of the GUI with one finger (though other swipe gestures with different numbers of points of contact, or other gestures altogether may be used). Different embodiments use different thresholds to determine how close the touch contact needs to be in order to be considered close to the edge for sliding the thumbnail display area back onto the GUI. The second stage  2720  illustrates the user moving her finger to the left, causing the thumbnail display area  1605  to begin sliding in that direction back onto the GUI. In the third stage  2730 , the user has released the swipe gesture as the thumbnail display area  1605  continues to slide onto the GUI to the left. The fourth stage  2340  illustrates that the thumbnail display area  1605  is fully present in the GUI, in the left-handed mode. 
     As shown in  FIG. 20 , some embodiments also transition from state  2060  to state  2065  and then  2050  when a user selects a grid button that causes the thumbnail display area to slide on and off of the GUI.  FIG. 28  illustrates the selection of such a GUI item  2505  in the GUI  1600  over four stages  2810 - 2840  while the GUI is in right-handed mode. As shown, in the first stage  2810 , the user taps the grid button  2505 . As with the swipe gestures, in some embodiments the operating system of the device translates the screen contact information into a tap gesture and a location and passes this information to the image-viewing application. The second stage  2820  and third stage  2830  illustrate the thumbnail display area  1605  sliding back onto the GUI. The resultant GUI shown in stage  2840  is the same as the resultant GUI at the end of  FIG. 26 , with the thumbnail display area  1605  appearing on the left side of the display. 
     The above description and figures highlighted various aspects of interacting with the GUI in left-handed and right-handed mode. In addition, certain differences exist between landscape mode (whether right-handed or left-handed) and portrait mode. One such difference involves the location and scrolling of the thumbnail display area. 
       FIG. 29  illustrates a user scrolling through the thumbnail display area  1605  over four stages  2910 - 2940  of the GUI  1600 . In the first stage  2910 , the user has begun to contact the touchscreen with one finger over the thumbnail display area  1605 . As shown in the second stage  2920 , the user moves the finger upwards while maintaining contact with the touchscreen. This has the effect of causing the thumbnails in the thumbnail display area to slide upwards, such that the top thumbnails disappear off of the screen and additional thumbnails appear at the bottom. At stage  2930 , the user continues this motion to continue scrolling through thumbnails. The fourth stage  2940  illustrates that the user has released the drag operation and the thumbnails have stopped scrolling. In some embodiments, depending on the speed of the drag/sweep gesture, the thumbnails may continue scrolling after the user releases the gesture (i.e., momentum scrolling). As all collections will contain a finite number of images, eventually the thumbnails will reach an end and stop scrolling. Furthermore, while this figure only shows scrolling down (via an upward touch gesture), users can also scroll up by dragging the thumbnail display downwards. 
     The above figures illustrate a GUI in both left- and right-handed landscape modes.  FIGS. 30-32 , on the other hand, illustrate a GUI  3000  of some embodiments in portrait mode. The GUI  3000 , as shown in  FIG. 30 , includes a thumbnail display area  3005 , an image display area  3015 , a first set of GUI items  3025 , a second set of GUI items  3035 , a third set of GUI items  3045 , a back button  3050 , an edit button  3055 , and a settings menu activation item  3060 . These are the same items as described above by reference to the GUI  1600  of  FIG. 16 . 
     As shown in these figures, the application displays the GUI items  3025 ,  3035 , and  3045 - 3060  in the same positions as in the right-handed mode of the landscape GUI  1600  (i.e., the edit activation GUI items  3025  on the bottom left, the back button  3050  and second set of GUI items  3035  on the top left, etc.). When in portrait mode, some applications do not provide a mechanism to switch from left-handed mode to right-handed mode, as the thumbnail display area  3005  is located at the bottom of the GUI anyway. Other embodiments, as mentioned above, may respond to an action indicative of the handedness of the user, such as a tap of five fingers at once (the relative locations being different for a left hand compared to a right hand). As described above, some embodiments determine the location of the various GUI items in portrait mode based on the most recently used landscape mode for the application. 
       FIG. 30  illustrates the GUI  3000  as a user scrolls through the thumbnails of a collection in the thumbnail display area over four stages  3010 - 3040 . In portrait mode, as shown, the application locates the thumbnail display area  3005  at the bottom of the GUI, although in other embodiments the thumbnail display might be at the top of the GUI. The thumbnail display area  3005  spans the width of the GUI, with a fixed number of columns of thumbnails (in this case five). In this figure, the thumbnail display area has a height of two thumbnails. 
     In the first stage  3010 , the user contacts the thumbnail display area with one finger. As shown in the second stage  3020 , the user has begun to slide the finger up over the thumbnail display area. This causes the thumbnails to slide upwards through the thumbnail display area  3005 , with new thumbnails beginning to appear at the bottom of the display area. The third stage  3030  illustrates that the user has continued to slide her finger upwards, with the thumbnails moving along as well. In the fourth stage  3040 , the user has released contact with the touchscreen, and therefore the thumbnails are no longer moving (although in some embodiments, the user can set the application or device to continue scrolling after a swipe gesture, based on the speed of the gesture). 
       FIG. 31  illustrates the modification of the size of the thumbnail display area  3005  over four stages  3110 - 3140  of the portrait GUI  3000 . As in landscape mode, the user can drag the boundary between the thumbnail display area  3005  and the image display area  3015  in order to modify the size of the thumbnail display area. However, whereas in landscape mode this boundary moves perpendicular to the direction of scrolling (and thus results in a rearrangement of the thumbnails when a threshold is passed and a column is added or subtracted), the boundary in portrait mode moves parallel to the direction of scrolling. As such, for the most part the thumbnail display area can be modified in a continuous manner without rearranging the thumbnails, rather than having discrete jumps when a column is added or subtracted. 
     The first stage  3110  illustrates the GUI  3000  with the thumbnail display area having a height of approximately two thumbnails. In the second stage  3120 , the user places a finger over the boundary between the thumbnail display area  3005  and the image display area  3015  and begins dragging the boundary downwards. In this case, the thumbnails move along with the boundary (i.e., the relationship of the boundary to the thumbnails does not change). In other embodiments, the thumbnails remain static during such a modification to the boundary, and the boundary moves over the thumbnails. When the user moves the boundary upwards and reaches the top row of thumbnails, some such embodiments then begin to move the thumbnails up with the boundary in order to prevent a gap from appearing at the top of the thumbnail display area. 
     The third stage  3130  illustrates that the user has continued to drag the boundary downwards, sliding the thumbnails further along as well. At the last stage  3140 , the thumbnail display area  3005  has a height of only one row. In some embodiments, when the thumbnail display area in portrait mode is reduced to only one row of thumbnails, the application automatically prevents the thumbnail display area from being reduced in size (although the user can still tap the grid button or use a swipe gesture to remove the thumbnail display area altogether) and modifies the direction of scrolling from vertical to horizontal. The application rearranges the thumbnails into a single row in the order they are stored in the currently selected collection, although the displayed thumbnails may appear the same to the user until the user begins to scroll. 
       FIG. 32  illustrates the horizontal scrolling of the thumbnail display area when sized down to one row, over four stages  3210 - 3240  of the GUI  3000 . The first stage  3210  illustrates the GUI  3000  in the same state as at stage  3140  of  FIG. 31 , with the thumbnail display area  3005  having a height of one row. As shown, the user has begun to contact the thumbnail display area with one finger. The user begins moving her finger to the left in the second stage  3220 , and continues this movement in the third stage  3230 . The result of this movement is that the thumbnails scroll to the left through the thumbnail display area  3005 , with some thumbnails scrolling off the GUI to the left and new thumbnails entering from the right. In some embodiments, the scrolling stops when the user reaches the end of the collection, while other embodiments wrap the thumbnails around in a continuous scrolling fashion. The fourth stage  3240  illustrates that the user has released contact with the touchscreen, and the thumbnails are now stationary. 
       FIG. 33  illustrates a user scrolling through images in the thumbnail display area of the mobile phone and media player GUI  1700  of some embodiments. In the first stage  3310 , a first thumbnail  3305  is selected, and the corresponding image  3315  has been displayed in the image display area  1715 . However, the user is currently performing a swipe gesture to the left over the image display area, beginning to reveal the next image in the collection. The second stage  3320  illustrates the result of this swipe gesture, with the image  3325  now displayed and the corresponding thumbnail  3335  selected. While not shown in the above figures, in some embodiments a user of the application on a larger (e.g., tablet) device may also use similar swipe gestures (both right and left) to quickly scan through the images in a collection. Scanning through sets of selected images with swipe gestures will also be described below in Section V. 
     The second through fourth stages  3320 - 3340  illustrate the user scrolling sideways through the thumbnail display area  1705  with a swipe gesture. As shown, the user swipes a finger sideways across the thumbnail display area, and the thumbnails slide through, as in  FIG. 32  above. 
     While the above figures illustrate scrolling through the thumbnail display areas (whether in portrait or landscape mode) using touchscreen gestures (including multi-touch gestures), one of ordinary skill in the art will recognize that the described features of  FIGS. 29-33  (as well as the other features shown throughout this document) may be performed in other manners—e.g., using a cursor controller device (which may involve a combination of button clicks, movement of the cursor controller, and touch input through the cursor controller), a keyboard, etc. 
     C. Zoom Tool 
     Subsection A of this section described an application with different GUIs for left- and right-handed modes, in which the application modifies the location and order of certain GUI elements while leaving others in the same place when switching between modes. In addition, some embodiments activate certain GUI tools differently (e.g., in different orientations) depending on whether the GUI is in the left-handed mode or the right-handed mode. One such tool is the zoom tool of some embodiments, which is displayed in different orientations and responds to certain gestures differently depending on which mode of the GUI is active. 
       FIG. 34  conceptually illustrates a process  3400  of some embodiments for invoking such a zoom tool. The process  3400  will be described by reference to  FIGS. 35 and 36 , which illustrate the invocation of the zoom tool within the right-handed and left-handed media-editing and viewing GUIs of some embodiments. The image viewing, editing, and organization application of some embodiments performs the process  3400  in response to a particular user input (e.g., touch) gesture received through the user interface of the application. However, some embodiments (e.g., some mobile phone and media player implementations of the application) do not include such a zoom tool. 
     As shown, the process begins by receiving (at  3405 ) two separate touch inputs over an image in the image display area while in the viewing mode. In some embodiments, the application is in viewing mode when the image display area displays one or more images and one of the sets of editing tools (e.g., the crop, exposure, color, brush, or special effects tools) have been activated. Some embodiments recognize two separate touch inputs as invoking the zoom tool when the two separate touch inputs are at least partly coincidental. That is, the two separate inputs need not contact the touchscreen at the same time (i.e., a user could place her thumb on the screen, then a second later contact the screen with her index finger in order to invoke the zoom tool so long as the thumb remains on the screen as well). Other embodiments place constraints on the time period between which the first and second touch inputs may be received (e.g., 0.5 seconds, 1 second, etc.). In addition, some embodiments only activate a zoom tool in response to touch inputs within a threshold distance (e.g., an absolute distance such as 3 inches or a distance relative to the size of the image). 
     Furthermore, some embodiments differentiate between a two-finger gesture and two separate gestures. Multi-touch devices can identify whether a user has placed one finger at a location on a touchscreen or multiple fingers together (e.g., for certain sweep gestures). These various touch gestures are detected by the device operating system and sent to the application in some embodiments. When the application receives two separate gestures from the operating system at different locations over the displayed image, the application invokes the zoom tool. 
     In response to receiving the two separate touch inputs, the process  3400  outputs (at  3410 ) a sound effect that is associated with a zoom tool display. In some embodiments, the sound effect mimics the sound of a camera shutter opening. Among other purposes, the sound effect indicates to the user that the zoom tool is activated. In addition, some embodiments display an animation within the area covered by the zoom tool that gives the appearance of a camera shutter opening. While the process  3400  illustrates the application outputting the sound effect before displaying the zoom tool, one of ordinary skill in the art will recognize that this is a conceptual process and the sound effect may be output in parallel with the display of the zoom tool. 
     The process also identifies (at  3415 ) a midpoint between the two separate touch inputs. As indicated, in some embodiments the application receives gesture information from the operating system in response to touch inputs received from a user. The gesture information includes a location at which each gesture is centered (e.g., screen pixel coordinates). The application of some embodiments identifies the midpoint of the line connecting the center coordinates of each gesture (e.g., the mean x coordinate and mean y coordinate). 
     The process then determines (at  3420 ) whether the GUI is in a right-handed mode. As mentioned above by reference to  FIG. 16 , the image-editing application provides a right-handed GUI and a left-handed GUI, between which users can switch. In some of these embodiments, the image editing application stores a parameter that indicates whether the GUI is in a right-handed mode or a left-handed mode. The application toggles the parameter when the user switches between the two modes (e.g., by moving the thumbnail display area). In these embodiments, the process determines whether the GUI is in the right-handed mode by checking this stored parameter. In other embodiments, the application uses the location of the thumbnail display area (or other GUI item) to determine whether the application is currently in left- or right-handed mode. 
     If the GUI is in the right-handed mode, the process displays (at  3425 ) a zoom tool centered at the identified midpoint, with magnification information displayed on the left side of the zoom ring. The process then ends. In some embodiments, the zoom tool is a zoom ring that appears as an ellipse (e.g., a circle) centered at the identified midpoint between the two touch inputs. Other embodiments, however, use different shapes (e.g., a square, hexagon, etc.). The magnification information, in some embodiments, indicates to the user the zoom level of the image inside the GUI control. 
       FIG. 35  illustrates an example of invoking and de-invoking a circular zoom tool through the GUI  3500  at four stages  3505 - 3520  while the GUI is in right-handed mode. The first and second stages  3505  and  3510  of  FIG. 35  illustrate the invocation of the zoom tool, while the third and fourth stages  3515  and  3520  illustrate the de-invocation of the zoom tool. 
     As shown, the GUI  3500  includes a thumbnail display area  3530  that is located on the left side of the GUI  3500 , an image display area  3545 , and a toolbar  3540 . The application displays an image  3555  within the image display area  3545 . As shown in the first stage  3505 , the thumbnail display area  3530  located on the left side of the GUI  3500 , which indicates that the GUI  3500  is in a right-handed mode. As none of the editing tool activation items in the toolbar  3540  are currently selected, the application is in viewing mode. 
     The second stage  3510  illustrates the GUI  3500  after a user has invoked a zoom tool on the image  3555 . As mentioned above, the zoom tool can be invoked by providing two separate touch inputs on an image. As shown, the user invokes the zoom tool by tapping two fingers at separate locations over the image  3555 , near a location that displays a golf ball. 
     As a result of the two touch inputs, a zoom ring  3525  is overlaid on the image  3555  centered at the midpoint between the two separate touch inputs (i.e., around a location in the image  3555  that includes a golf ball, now shown as magnified). In addition, since the GUI is in the right-handed mode as indicated by the location of the thumbnail display area  3530 , the magnification information  3535  is displayed on the left side of the zoom ring  3525 . This magnification information indicates that the current zoom level inside the zoom ring  3525  is 2×. Displaying the magnification information on the left side of the zoom ring  3525  makes this information easily visible to the user while her right hand is over the zoom tool. As will be explained below, the user can use rotation gestures in order to change the magnification level. 
     Referring back to  FIG. 34 , when the process  3400  determines that the GUI is not in a right-handed mode at operation  3420  (and thus that the GUI is in left-handed mode), the process displays (at  3430 ) a zoom tool centered at the identified midpoint, with magnification information displayed on the right side of the zoom ring. The process then ends. In some embodiments, the zoom tool is a zoom ring (e.g., a circle) that has the same shape whether in left-handed or right-handed mode. 
       FIG. 36  illustrates an example of invoking a circular zoom tool through the GUI  3500  when the GUI is in a left-handed mode at two stages  3605  and  3610 . As shown, the first stage  3605  is identical to the first stage  3505  of  FIG. 35 , except that the GUI  3500  in  FIG. 36  is in left-handed mode, with the thumbnail display area  3530  located on the right side of the GUI  3500 . 
     The second stage  3605  illustrates the GUI  3500  after the user has invoked a zoom tool on the image  3555 . As mentioned above, the zoom tool can be invoked by providing two separate touch inputs on an image. As shown, the user invokes the zoom tool by tapping two fingers at separate locations over the image  3555 , near a location that displays a golf ball. 
     As a result of the two touch inputs on the image  3555 , a zoom ring  3525  is overlaid on the image  3555  centered at the midpoint between the two separate touch inputs (i.e., around a location in the image  3555  that includes a golf ball, now shown as magnified). In addition, since the GUI is in the left-handed mode as indicated by the location of the thumbnail display area  3530 , the magnification information  3535  is displayed on the right side of the zoom ring  3525 . This magnification information indicates that the current zoom level inside the zoom ring  3525  is 2×. Displaying the magnification information on the right side of the zoom ring  3525  makes this information easily visible to the user while her left hand is over the zoom tool. As will be explained below, the user can use rotation gestures in order to change the magnification level. 
     With the zoom tool invoked and displayed over an image (i.e., overlaid on the image), the image editing application also allows the user to deselect or de-invoke the zoom tool. Different embodiments of the application provide different manners in which a user can deselect the zoom tool. For instance, the application of some embodiments removes the zoom tool when a touch input is received on the image but outside of the zoom tool. 
     Referring back to  FIG. 35 , the third and fourth stages  3515  and  3520  illustrate an example of the deselection of a zoom tool through the GUI  3500 . The GUI in the third stage  3515  is identical to the second stage  3510 , with the zoom ring  3525  still overlaid on the image  3555 , with the golf ball and surrounding grass magnified. The fourth stage  3520  illustrates the GUI  3500  after the user has deselected the zoom tool. As mentioned, a user may deselect a zoom tool by providing a touch input on the image outside of the zoom tool. As shown, the user has deselected the zoom tool  3525  by tapping a finger at a location on the image  3555  outside of the zoom tool  3525 . As a result of the single touch input outside of the zoom ring, the application removes the zoom ring  3525  from the GUI  3500 . In some embodiments, the application also displays a sound effect (e.g., the sound of a camera shutter closing) as the zoom tool is de-invoked. Some embodiments also display a corresponding animation of a camera shutter closing within the zoom tool as the tool is being removed. 
     In addition to simply invoking and removing the zoom tool of some embodiments, users can move the zoom tool to different locations in the image in order to zoom in on different sections, modify the magnification level of the region shown within the zoom tool, and perform other operations. These operations will now be described by reference to  FIG. 37 . 
       FIG. 37  conceptually illustrates a state diagram  3700  that presents various operations of the zoom tool within the GUI of some embodiments. One of ordinary skill in the art will recognize that the state diagram  3700  does not encompass every state of the image viewing GUI, or even every state of the zoom tool, but instead only a subset of the zoom tool operations within the image viewing GUI. 
     The state diagram  3700  will be described by reference to the UI examples illustrated in  FIGS. 38, 39, 41, 42, and 40 . Specifically,  FIGS. 38 and 41  show the GUI of the image viewing and editing application of some embodiments in multiple stages related to the magnifying (i.e., zooming in) operation of the zoom tool.  FIGS. 39 and 42  show the GUI of the image viewing and editing application of some embodiments in multiple stages related to the de-magnifying (i.e., zooming out) operation of the zoom tool.  FIG. 40  shows the GUI of the image viewing and editing application of some embodiments in multiple stages related to the relocation (i.e., moving) of the zoom tool. 
     As shown in  FIG. 37 , the GUI has two initial states  3705  and  3710 . At the initial state  3705 , the GUI displays a thumbnail grid (i.e., a thumbnail display area) and an image displayed in an image display area in the right-handed mode. The state  3710  is identical to the state  3705 , with the exception that the GUI is in the left-handed mode instead of a right-handed mode, and thus the thumbnail grid is on the right side of the GUI. The various operations of the zoom tool in right-handed mode will be described first by reference to  FIGS. 38, 39, and 40 . 
     When the zoom tool receives two separate touch inputs over the image, the zoom tool transitions from the initial state  3705  to state  3715 , at which the GUI displays a zoom ring on the image in the right-handed mode. As described above, the GUI provides two different versions of the zoom ring in some embodiments, one for the right-handed mode and one for the left-handed mode. In some embodiments, the zoom ring in the right-handed mode has the magnification information displayed on the left side of the zoom ring. This enables the user to view the magnification information while her right hand is over the zoom ring. The operations of invoking and displaying the zoom ring in the right-handed mode are described in details above by reference to  FIG. 35 . 
     The zoom tool stays at state  3715  so long as there is no input provided to affect the zoom ring. However, when a clockwise rotation input is received, the GUI transitions to state  3725  to increase the magnification of the area of the image within the zoom tool. In some embodiments, a user can provide a clockwise rotation input by putting two fingers on the zoom ring and rotating the two fingers in a clockwise direction. Some embodiments identify such input by tracking the location of the inputs and measuring the angle (e.g., the angle off the horizontal) of the line connecting the two locations. When this angle changes in a clockwise manner, the application increases the magnification of the right-handed zoom tool. In some embodiments, the two touch inputs need not be located directly over the zoom tool, though doing so will often help the user visualize the zoom in and zoom out movements. After increasing the magnification of the area of the image that is inside the zoom ring, the GUI returns to state  3715  so long as the user is not continuing to rotate her fingers in a clockwise manner. 
       FIG. 38  illustrates the magnification operation of the zoom tool through the GUI  3500  at four different stages  3805 - 3820 . The first stage  3805  is identical to the first stage  3505  of  FIG. 35 , with the thumbnail display area  3530  located on the left side of the GUI  3500 , and the image  3555  displayed in the image display area  3545  in viewing mode. 
     The second stage  3810  illustrates the GUI  3500  after the user has invoked the zoom tool by providing two separate touch inputs on the image  3555 . As shown, the user has tapped two fingers on the image  3555  around the location of the golf ball. As a result of the two separate touch inputs, the application overlays a zoom ring  3525  on the image  3555  centered at the midpoint between the two separate touch inputs. In addition, as the GUI is in the right-handed mode, the application displays magnification information  3535  on the left side of the zoom ring  3525 . In some embodiments, the default magnification is a 2× zoom, with the magnification variable between 1× and 3×. 
     The third stage  3815  illustrates the GUI  3500  after the user has started to increase the magnification of the image using the zoom tool. As mentioned, the user can increase the magnification of the area of the image inside the zoom tool by providing clockwise rotation input. As shown, the user has begun to rotate the two fingers in the clockwise direction, as indicated by the arrow  3825 . As a result of the clockwise rotation input, the area of the image that is inside the zoom ring  3525  is displayed as further magnified. 
     The fourth stage  3820  illustrates the GUI  3500  after the user has further increased the magnification of the image using the zoom tool. As shown, the user has continued to rotate the two fingers in the clockwise direction, as indicated by the arrow  3830 . As a result of the rotation movement, the area of the image inside the zoom ring  3525  in the fourth stage  3820  is more magnified than the image in the third stage  3815 . At this stage, the zoom tool is at the maximum 3× magnification level. 
     In some embodiments, the zoom tool will not magnify a portion of an image past its full size display. Images on smaller-screen devices are often reduced in size in order to fit within the display of the device. For example, a 1920×1080 image may not be displayed at full size on a 640×480 display screen. Using the zoom tool enables the user to view a portion of an image at closer to its full size. However, when an image is already at its full size (e.g., a 640×480 image on a 1920×1080 display screen), then some embodiments will not allow a user to invoke the zoom tool, as this would create pixelation within the zoomed area. 
     Referring back to  FIG. 37 , when the application receives a counter-clockwise rotation input while at state  3715 , the GUI transitions to state  3735  to decrease the magnification of the area of the image within the zoom tool. In some embodiments, a user can provide a counter-clockwise rotation input by putting two fingers on the zoom ring and rotating the two fingers in a counter-clockwise direction. As with the clockwise rotation, some embodiments identify the input by tracking the location of the two inputs and measuring the angle of the line connecting the locations. After decreasing the magnification of the area of the image inside the zoom ring, the GUI returns to state  3715  so long as the user is not continuing to rotate her fingers. 
       FIG. 39  illustrates the de-magnification operation of the zoom tool through the GUI  3500  at four different stages  3905 - 3920 . The GUI  3500  at the first stage  3905  is identical to the GUI at the fourth stage  3820  of  FIG. 38 . As shown, the GUI  3500  includes the zoom ring  3525  at 3× magnification and the area of the image inside the zoom ring is magnified. 
     The second stage  3910  illustrates the GUI  3500  after the user has started to decrease the magnification of the image using the zoom tool. As mentioned, the user can decrease the magnification of the area of the image inside the zoom ring by providing a counter-clockwise rotation input. As shown, the user has begun to rotate the two fingers in the counter-clockwise direction, as indicated by the arrow  3925 . As a result of the counter-clockwise rotation input, the application has decreased the magnification of the area of the image that is inside the zoom ring  3525 . 
     The third stage  3915  illustrates the GUI  3500  after the user has further decreased the magnification of the image using the zoom tool. As shown, the user has continued to rotate the two fingers in the counter-clockwise direction, as indicated by the arrow  3930 . As a result of the rotation movement, the area of the image inside the zoom ring  3525  in the third stage  3915  is less magnified than at the second stage  3910 . The fourth stage  3920  illustrates the GUI  3500  after the user has lifted the two fingers off the zoom ring  3525 . As shown, the area of the image inside the zoom ring  3525  remains the same as the area of the image in the third stage  3915  after the user has lifted off the fingers. 
     In addition to changing the magnification level of the zoom tool, some embodiments allow the user to move the tool around the image, thereby focusing on different areas within an image. Referring back to  FIG. 37 , when the zoom tool receives a ring movement activation event, the zoom tool transitions to the move ring state  3745 . In some embodiments, a ring movement activation event includes a user pressing and holding a finger (i.e., a single touch) on the zoom ring. During the move ring state  3745 , the zoom ring follows the movement of the user&#39;s input. That is, the zoom ring moves to wherever the user moves the finger. The zoom tool stays in this state until receiving a zoom ring movement deactivation event. In some embodiments, the user can deactivate the zoom ring movement operation by lifting the finger off the zoom ring. Upon receiving the zoom ring movement deactivation event, the zoom tool returns to state  3715 . 
       FIG. 40  illustrates the move operation of the zoom tool through the GUI  3500  at four different stages  4005 ,  4010 ,  4015 , and  4020 . The first stage  4005  is identical to the first stage  3505  of  FIG. 35 . As shown, the GUI  3500  includes a thumbnail display area  3530  that is located on the left side of the GUI  3500 , an image display area  3545 , and a menu bar  3540 . An image  3555  is displayed in the image display area  3545  in a view mode. In addition,  FIG. 40  also shows that the GUI  3500  is in a right-handed mode, as indicated by the thumbnail display area  3530  located on the left side of the GUI  3500 . 
     The second stage  4010  illustrates the GUI  3500  after a user has invoked the zoom tool. As shown, the user has invoked the zoom tool by providing two separate touch inputs on the image  3555 . As a result of the two separate touch inputs, the application overlays the zoom ring  3525  on the image  3555  centered at the midpoint between the two separate touches. In addition, as the GUI  3500  is in the right-handed mode (indicated by the location of the thumbnail display area  3530 ), the GUI displays the magnification information  3535  on the left side of the zoom ring  3525 . 
     The third stage  4015  illustrates the GUI  3500  after the user has started to move the zoom ring  3525  with a touch gesture. In some embodiments, a user can move the zoom ring by placing a single finger on the zoom ring  3525  and dragging the finger to another location on the image. As shown, the user has begun to drag the finger towards the upper right corner of the image  3555 , as indicated by the arrow  4025 . As a result of the drag movement, the zoom ring  3525  moves toward the upper right corner of the image  3555 . The fourth stage  3915  illustrates the GUI  3500  after the user has moved the zoom ring  3525  to another location on the image. As shown, the user has dragged the finger toward the top of the image  3555 , as indicated by the arrow  4030 . As a result of the drag movement, the zoom ring  3525  now moves toward the top of the image  3555 . 
     In some embodiments, the zoom tool can be deactivated by a zoom tool deactivation event. For example, the zoom tool can be deactivated when a single input is received outside of the zoom ring. Referring back to  FIG. 37 , when the zoom tool receives an input outside of the zoom ring (e.g., a single touch outside of the zoom ring) while at state  3715 , the zoom tool transitions back to the initial state  3705 . The deactivation operation of the zoom ring of some embodiments is described in detail above by reference to stages  3515  and  3520  of  FIG. 35 . 
     As described in detail above, a user can toggle the image-viewing and editing GUI from right-handed mode to left-handed mode by moving the thumbnail display area (i.e., the thumbnail grid) to the right side of the GUI. Thus, while at the initial state  3705 , the zoom tool transitions to the other initial state  3710  when the user moves the thumbnail grid to the right side of the display (and vice versa if the user moves the thumbnail grid back to the left side). The various operations of the zoom tool that star with the initial state  3710  will be now described by reference to  FIGS. 41 and 42 . These operations are similar to the right-handed operations, except that the magnification and de-magnification operations are caused by rotation in the reverse directions. 
     When the zoom tool receives two separate touch inputs over the image, the zoom tool transitions from the initial state  3710  to state  3720 , at which the GUI displays a zoom ring on the image in the left-handed mode. As described above, the GUI provides two different versions of the zoom ring in some embodiments, one for the right-handed mode and one for the left-handed mode. In some embodiments, the zoom ring in the left-handed mode has the magnification information displayed on the right side of the zoom ring. This enables the user to view the magnification information while her left hand is over the zoom ring. The operations of invoking and displaying the zoom ring in the left-handed mode are described in detail above by reference to  FIG. 36 . 
     The zoom tool stays at state  3720  so long as there is no input provided to affect the zoom ring. However, when a counter-clockwise rotation input is received, the GUI transitions to state  3730  to increase the magnification of the area of the image within the zoom tool. In some embodiments, a user can provide a counter-clockwise rotation input by putting two fingers on the zoom ring and rotating the two fingers in a counter-clockwise direction. Some embodiments identify such input by tracking the location of the inputs and measuring the angle (e.g., the angle off the horizontal) of the line connecting the two locations. When this angle changes in a counter-clockwise manner, the application increases the magnification of the left-handed zoom tool. In some embodiments, the two touch inputs need not be located directly over the zoom tool, though doing so will often help the user visualize the zoom in and zoom out movements. After increasing the magnification of the area of the image that is inside the zoom ring, the GUI returns to state  3720  so long as the user is not continuing to rotate her fingers in a counter-clockwise manner. 
       FIG. 41  illustrates the magnification operation of the zoom tool through the GUI  3500  at four different stages  4105 - 4120 . The first stage  4105  is identical to the first stage  3605  of  FIG. 36 , with the thumbnail display area  3530  located on the right side of the GUI  3500 , and the image  3555  displayed in the image display area  3545  in viewing mode. 
     The second stage  4110  illustrates the GUI  3500  after the user has invoked the zoom tool by providing two separate touch inputs on the image  3555 . As shown, the user has tapped two fingers on the image  3555  around the location of the golf ball. As a result of the two separate touch inputs, the application overlays a zoom ring  3525  on the image  3555  centered at the midpoint between the two separate touch inputs. In addition, as the GUI is in the left-handed mode, the application displays magnification information  3535  on the left side of the zoom ring  3525 . In some embodiments, the default magnification is a 2× zoom, with the magnification variable between 1× and 3×. 
     The third stage  4115  illustrates the GUI  3500  after the user has started to increase the magnification of the image using the zoom tool. As mentioned, the user can increase the magnification of the area of the image inside the zoom tool by providing counter-clockwise rotation input. As shown, the user has begun to rotate the two fingers in the counter-clockwise direction, as indicated by the arrow  4125 . As a result of the counter-clockwise rotation input, the area of the image that is inside the zoom ring  3525  is displayed as further magnified. 
     The fourth stage  4120  illustrates the GUI  3500  after the user has further increased the magnification of the image using the zoom tool. As shown, the user has continued to rotate the two fingers in the counter-clockwise direction, as indicated by the arrow  4130 . As a result of the rotation movement, the area of the image inside the zoom ring  3525  in the fourth stage  4120  is more magnified than the image in the third stage  3815 . At this stage, the zoom tool is at the maximum 3× magnification level. 
     Referring back to  FIG. 37 , when the application receives a clockwise rotation input while at state  3720 , the GUI transitions to state  3740  to decrease the magnification of the area of the image within the zoom tool. In some embodiments, a user can provide a clockwise rotation input by putting two fingers on the zoom ring and rotating the two fingers in a clockwise direction. As with the counter-clockwise rotation, some embodiments identify the input by tracking the location of the two inputs and measuring the angle of the line connecting the locations. After decreasing the magnification of the area of the image inside the zoom ring, the GUI returns to state  3720  so long as the user is not continuing to rotate her fingers. 
       FIG. 42  illustrates the de-magnification operation of the zoom tool through the GUI  3500  at four different stages  4205 - 4220 . The GUI  3500  at the first stage  4205  is identical to the GUI at the fourth stage  4120  of  FIG. 41 . As shown, the GUI  3500  includes the zoom ring  3525  at 3× magnification and the area of the image inside the zoom ring is magnified. 
     The second stage  4210  illustrates the GUI  3500  after the user has started to decrease the magnification of the image using the zoom tool. As mentioned, the user can decrease the magnification of the area of the image inside the zoom ring by providing a clockwise rotation input. As shown, the user has begun to rotate the two fingers in the clockwise direction, as indicated by the arrow  4225 . As a result of the clockwise rotation input, the application has decreased the magnification of the area of the image that is inside the zoom ring  3525 . 
     The third stage  4215  illustrates the GUI  3500  after the user has further decreased the magnification of the image using the zoom tool. As shown, the user has continued to rotate the two fingers in the clockwise direction, as indicated by the arrow  4230 . As a result of the rotation movement, the area of the image inside the zoom ring  3525  in the third stage  4215  is less magnified than at the second stage  4210 . The fourth stage  4220  illustrates the GUI  3500  after the user has lifted the two fingers off the zoom ring  3525 . As shown, the area of the image inside the zoom ring  3525  remains the same as the area of the image in the third stage  4215  after the user has lifted off the fingers. 
     As with the right-handed zoom tool, the user can move the tool around to different areas of the image in left-handed mode. While the gestures for magnification and de-magnification are in opposite directions for the left-handed and right-handed modes, moving the zoom ring involves the same gesture in either mode in some embodiments. Referring back to  FIG. 37 , when the zoom tool receives a ring movement activation event, the zoom tool transitions to the move ring state  3750 . In some embodiments, a ring movement activation event involves a user pressing and holding a finger (i.e., a single touch input) on the zoom ring. During the move ring state  3750 , the zoom ring follows the movement of the user&#39;s input. That is, the zoom ring moves to wherever the user moves the finger. The zoom tool stays in this state until receiving a zoom ring movement deactivation event. In some embodiments, the user can deactivate the zoom ring movement operation by lifting the finger off the zoom ring. Upon receiving the zoom ring movement deactivation event, the zoom tool returns to state  3720 . When the zoom tool receives an input outside of the zoom ring (e.g., a single touch outside of the zoom ring) while at state  3720 , the zoom tool transitions back to the initial state  3710 , with the GUI in left-handed mode. 
     IV. Display of Multiple Images 
     While many of the above examples show a GUI with only one image in the image display area, some embodiments allow the user to select several images for display at once. In various embodiments, different processes are available to the user in order to display multiple images. The user can select a particular image in a collection (by selecting the corresponding thumbnail with a particular type of selection input) and the application automatically identifies any other images in the collection that are within a threshold similarity of the selected image. In addition, the user can select a block of images in the thumbnail display area (e.g., through separate inputs on a multi-touch device) or several individual images by pressing and holding each thumbnail for a threshold duration. In addition, some embodiments include a settings menu option for selecting multiple images at once. 
     When multiple images are selected for display in the image display area, some embodiments use a display algorithm that maximizes usage of the display while ensuring that the visual weighting is equal across all the images. In some embodiments, the application identifies the average aspect ratio of the images to display, then divides the image display area into the ideal grid for the number of images, with each rectangular region of the grid having the average aspect ratio. The application then fits each of the images into one of the grid rectangles. 
     A. Identification and Display of Similar Images 
     As mentioned, one of the methods for selecting multiple images for display in the image display area is to select an image and cause the application to identify any images in the same collection that are within a threshold similarity of the selected image. In some embodiments, when a user double taps (or double clicks) on a thumbnail, the application automatically compares other images in the collection to the selected image. To perform a comparison between two images, some embodiments use a set of histograms for each of the images, and determine whether the image histograms are within the threshold similarity. Some embodiments use color, texture, and gradient histograms, though other embodiments may use other pixel properties to compare the images. In order to focus the comparison on the more important portions of the image (e.g., the center), some embodiments divide the image into several regions and compare the histograms for corresponding regions. The regions may be overlapping such that some pixels (e.g., those in the center of the image) are used for more regions than other pixels. 
       FIG. 43  conceptually illustrates a process  4300  of some embodiments for identifying and displaying similar images within a collection. The image viewing, editing, and organization application of some embodiments performs this process in response to a user command to display the similar images while the application is in viewing mode. The process  4300  will be described in part by reference to  FIGS. 44-46 .  FIG. 44  illustrates a GUI  4400  for an image viewing application over three stages  4410 - 4430  in which a user selects a particular image and the application identifies the set of images within a collection that are similar to the selected image. 
     The GUI  4400  includes a thumbnail display area  4405  and an image display area  4415 . These display areas are similar to those described above for  FIG. 14 . As indicated in the bar above the image display area  4415 , the thumbnail display area  4405  displays a set of thumbnails for images in the collection “Album 1”. 
     As shown, the process  4300  begins by receiving (at  4305 ) a selection of a particular image within an album and a command to identify similar images. As mentioned, some embodiments automatically perform this process when a user double taps (i.e., two rapid successive taps within a threshold duration over the same thumbnail) or double clicks on a thumbnail of an image. However, this feature could also be accessed through other GUI interactions, such as selecting a menu option or a separate GUI item with an image selected, typing a set of keystrokes, etc. 
     The first stage  4410  of  FIG. 44  illustrates that none of the thumbnails in the thumbnail display area  4405  are presently selected. In the second stage  4420 , the user double taps the thumbnail  4425  with a single finger. This image shows a golfer having just hit a golf ball. As can be seen in the thumbnail display area  4405 , the collection includes four other images of this golf scene, as well as various unrelated images. 
     Next, the process  4300  outputs (at  4310 ) a sound effect associated with the image comparison operation. One of ordinary skill in the art will recognize that various different embodiments may use different sound effects, and some may not output a sound effect at all. In some embodiments, the sound effect used may be designed to simulate a person shuffling through a large set of physical photographs, or be evocative of a processor performing computations. While the output of the sound effect is conceptually shown in the process  4300  as performed prior to the comparison operations, in many cases the processor on the device that runs the application will perform the computations necessary for the comparison during the time that the device outputs the sound effect. 
     The process then retrieves (at  4315 ) statistics for the selected image. In some embodiments, the statistics comprise a set of histograms that provide information about the image. The histograms, in some embodiments, provide information about the distribution of color in the image, the variability of the color within the image, and the shapes present in the image. As described in further detail below by reference to  FIG. 47 , the application of some embodiments places each pixel into a color range, a texture range, and a gradient range. The color identifies the location of the pixel in a particular color space, the texture identifies how similar or different a pixel&#39;s color data is to that of its neighbors, and the gradient identifies a direction and amount of the pixel&#39;s change in intensity relative to its neighbors. In addition to these (and other) histograms, some embodiments also use other information to compare images, such as filenames, user-entered descriptions, Exif data, etc. 
     In some embodiments, the application divides up the images into several regions and compares histograms for corresponding portions of two images. Different embodiments divide the images differently.  FIG. 45  conceptually illustrates one such division of an image  4500  into nine different tiles, each of which is one-fourth the size of the image.  FIG. 45  uses four panels  4505 - 4520  to illustrate the nine tiles  4525 - 4565 . The first four tiles  4525 - 4540  are the four corner regions of the image  4500 . The next two tiles  4545  and  4550 , in panel  4510 , occupy the vertical center of the image, while the tiles  4555  and  4560 , in panel  4515 , occupy the horizontal center of the image. Finally, the last panel  4520  has only one tile  4565  that is centered at the actual centerpoint of the image. 
     Using this particular set of regions gives more weight to some pixels of the image than others, such that these pixels are more important in the comparison of two images.  FIG. 46  indicates the 16 quadrants of pixels that result from this particular division of the image  4500 , and which of the tiles  4525 - 4565  include pixels from each quadrant. As shown, the quadrants in the four corners are only included in one of the tiles, and thus these pixels contribute to only one of the nine sets of histograms for the image. The eight quadrants that border only one edge of the image are each included in two tiles, while the four center quadrants are each included in four tiles. Thus, the center pixels will be weighted four times more heavily than the corner pixels in a comparison with a different image. 
     The application calculates the histograms (and any other statistics) in advance, in some embodiments, rather than performing all of the calculations when asked to identify similar images. Some embodiments generate the histograms for an image when the application first imports the image, and store the histograms for the image with the image (e.g., as part of the additional data in the image data structure  1500  of  FIG. 15 , described above). With three histograms each for nine tiles, some embodiments store twenty-seven different histograms for each image. 
     Returning to  FIG. 43 , the process  4300  then selects (at  4320 ) a new comparison image from the currently displayed collection (of which the initially selected image is a part). Some embodiments traverse through the images starting at the beginning of the ordered series stored in the collection data structure, while other embodiments start with the next image after the selected image in the ordered series, select the images in the collection randomly, or use another algorithm. 
     The process then retrieves (at  4325 ) the statistics for the current comparison image. These statistics are the same statistics as were retrieved for the user-selected image (i.e., histograms of the color, texture, and gradient of the various different regions of the image). As stated above, some embodiments pre-compute these histograms and store the histograms with the data structure for the image. 
     Next, the process  4300  compares (at  4330 ) the statistics of the particular user-selected image to the statistics of the current comparison image. Different embodiments perform this comparison differently. Some embodiments compare each histogram of the selected image to the corresponding histogram of the current comparison image. For instance, the Tile 1 color histogram for the first image is compared to the Tile 1 color histogram for the second image, the Tile 5 texture histogram for the first image is compared to the Tile 5 texture histogram for the second image, etc. As such, some embodiments perform twenty-seven different comparisons for use in determining whether two images qualify as similar. 
     For comparing histograms from different images, different embodiments use different techniques. Each histogram is a set of bins defined by ranges of values. The bins may be one dimensional or multi-dimensional. For instance, texture is defined by a single value, and thus each bin is a range of this texture value. The gradient for a pixel is defined as a vector with both an angle and a length (or, alternatively, an x-direction value and a y-direction value). Thus, each bin will contain pixels that fall within a particular range of angles and a particular length. The color value of a pixel is often a three-dimensional value in a color space (e.g., RGB space, HSL space, YCbCr space, or a different color space). Thus, each bin will have a defined range in each of the three dimensions, as described in further detail below by reference to  FIGS. 48-50 . 
     The application compares the number of pixels in each bin of the first image&#39;s histogram with the number of pixels in each corresponding bin of the second image&#39;s corresponding histogram. Some embodiments use a root mean square function to calculate the difference between two histograms, which takes the square root of the average of the squares of the differences for each bin of the histogram. As a simplified example, if a first histogram has values of [4, 2, 1, 5] and a second histogram has values of [3, 2, 4, 3], then the root mean square function is:
 
Sqrt[{(4−3) 2 +(2−2) 2 +(1−4) 2 +(5−3) 2 }/4]=Sqrt(3·5)=1.87.
 
     The application then compares the root mean square output to the total number of pixels in the histogram (i.e., one-fourth the number of pixels of the image) to determine a comparison score. This comparison score is computed for each of the histograms (i.e., twenty-seven different histograms in the example shown). Rather than a root mean square analysis, some embodiments use a simple average of the deviation between two histograms, or some other algorithm that quantifies the difference between two histograms. 
     In order to compare histograms of images with different numbers of pixels, some embodiments determine the ratio of the pixel counts and multiply the histogram values of the smaller image by this amount. Other embodiments only compare images with the same number of pixels and aspect ratio. 
     Some other embodiments divide each histogram value by the total number of pixels in the image (or tile), thus having a histogram of fractions that sums to 1 over the entire histogram. In some such embodiments, the application uses a square root of multiplication function to compare histograms. This function takes the square root of each bin value in a first histogram multiplied by its corresponding bin value in the second histogram, then sums these square roots over the entire set of bins in the histograms. Thus, for a first simple histogram with values of [0.1, 0.4, 0.3, 0.2] and a second histogram with values of [0.35, 0.25, 0.3, 0.1], the score would be Sqrt(0.1*0.35)+Sqrt(0.4*0.25)+Sqrt(0.3*0.3)+Sqrt(0.2*0.1)=0.9447. This comparison method gives a score of 1 if the histograms are identical, and decreases as the histograms become more and more different. 
     Another method employed by some embodiments uses a summation of overlapped significant bins. This process only counts bins for which the values in both histograms are greater than a particular threshold value. The threshold might be a particular percentage of the total pixels used to generate the histogram, or a function of the number of bins (e.g., 5/N, where N is the number of bins). When the value of a bin for both the first and second histogram is greater than the threshold, these values are added to the total score for the histogram comparison. In this comparison, the scores can range from 0 (if there are no overlapping significant bins) to 2 (if all pixels are in overlapping significant bins). This comparison technique prevents differences in the small (and therefore less meaningful) histogram bins from obfuscating the comparison process. 
     With the statistics for the two images compared, the process  4300  determines (at  4335 ) whether the images are within a threshold similarity. In some embodiments, the application averages the comparison scores for each of the histograms and determines whether the average score falls within a threshold. This ensures that smaller differences (e.g., the presence vs. absence of an item in the corner of the image) do not prevent two otherwise similar images from being identified as such. 
     Other embodiments perform a first average over the color histogram differences, a second average over the texture histogram differences, and a third average over the gradient histogram differences. Some such embodiments require all three average comparison scores to fall within the threshold, while others only require two of the three average scores to meet the threshold. In yet other embodiments, the application compares each of the histogram comparison scores to a threshold, and requires a particular number of the scores (e.g., all of them, eighteen of the twenty-seven, etc.) to meet the threshold in order for the two images to be considered similar. 
     In some embodiments, the application uses different threshold similarities for the color, gradient, and texture histograms. For instance, the application might allow greater variability in the color histograms than the gradient histograms, as doing so would allow for different exposure images or cloudy vs. sunny images to be considered similar when they have the same shape. 
     The similarity thresholds, in some embodiments, are based on a machine-learning decision tree technique. This technique uses sample image pairs that have been previously classified as either similar or not similar, and calculates different comparison scores for the images (e.g., using one or more of the comparison techniques described above). These scores are then analyzed for the similar and non-similar pairs in order to identify useful threshold values or combinations of thresholds for the comparison scores. 
     When the images are within the threshold similarity, the process adds (at  4340 ) the current comparison image to the group of images classified as similar to the particular image. That is, the current comparison image becomes one of the selected images that will be displayed in the image display area along with the user-selected image and any other similar images. 
     The process  4300  next determines (at  4345 ) whether the current collection contains any additional images that the process has not yet compared to the particular user-selected image. As mentioned, the application traverses through the entire collection, even if the collection includes all of the images imported by the application. When additional images remain, the process returns to  4320  to set the next image as the current comparison image. 
     Once all images in the current collection have been compared to the user-selected image, the process displays (at  4350 ) the particular user selected image and its similar images in the image display area. Returning to  FIG. 44 , the third stage  4430  shows the result of the user selecting the thumbnail  4425  with a double-tap input. In this stage, the application displays four images  4435 - 4450  in the image display area. These are four of the five images that show the golfer. The fifth image, thumbnail  4455  is dissimilar enough to not be considered similar (e.g., because the different location of the golf club causes enough of a gradient difference or because the darkness of the image causes enough of a color difference). The thumbnails for the images  4435 - 4450  now have a highlighted border in order to indicate that these images are selected for viewing. Some embodiments display the images in the image display area  4415  according to an algorithm that maintains an equal visual weighting across all of the images (although that is not an issue in this case because the aspect ratio is equal for the images). 
     The process  4300  of  FIG. 43  describes how the application performs a comparison between multiple images by comparing various histograms for the image.  FIG. 47  conceptually illustrates a process  4700  for generating a set of histograms according to some embodiments of the invention. As stated, some embodiments pre-compute the histograms (e.g., generate the histograms at the time of import of the image, and save them with the image), and thus perform the process  4700  or a similar process for each image when the image is imported into the application. The process  4700  will be described in part by reference to  FIGS. 48-50 , which conceptually illustrate a color space commonly used by the application to generate a set of color histograms for an image. 
     As shown, the process  4700  begins (at  4705 ) by receiving an image. Typical images comprise a set of pixels arranged in a rectangle. Each pixel is generally defined by (i) a set of color values in a particular color space and (ii) a location in the rectangle. The image may be in an encoded form, in which case the application decodes the image in order to identify the color values for the pixels of the image. 
     The process calculates (at  4710 ) the dimensions within the image of the different tiles for which it will generate histograms. As described above by reference to  FIGS. 45 and 46 , some embodiments generate three histograms for each of nine different tiles. The process determines the pixel dimensions of each of the tiles. For instance, if an image has pixel dimensions of 640×480 (i.e., 640 pixels in the horizontal direction and 480 pixels in the vertical direction), the Tile 1  4525  will use the rectangle of pixels with corners at (1, 1) (the left corner of the image) and (320, 240) (the center of the image), while Tile 9  4565  will use the rectangle from pixel location (161, 121) to (480, 360). 
     The process then selects (at  4715 ) the next pixel of the image. Some embodiments traverse each row of pixels, starting at pixel (1, 1) in the top left corner, traversing along top row first, and then down to the next row, etc. Other embodiments select pixels in a different manner (e.g., randomly, column first, etc.). 
     Next, the process  4700  identifies ( 4720 ) all tiles of the image to which the selected pixel belongs. Using the tiling scheme shown in  FIGS. 45 and 46 , pixels located towards the corners will only belong to one region of the image, while pixels located in the center will belong to four regions. Using this scheme, pixels in quadrants near only one edge belong to two regions. 
     The process next begins generating the histograms. In this example process  4700 , the application generates the color value first, then the texture value, and finally the gradient value. However, one of ordinary skill in the art will recognize that different embodiments will perform these computations in a different order, or perform them in parallel. 
     The process converts (at  4725 ) the pixel values to hue-saturation-value (HSV) color space. The stored pixel values are often in a device-specific RGB color space, and conversion to HSV entails only a simple transformation.  FIG. 48  conceptually illustrates the HSV color space  4800 , which is a cylindrical coordinate system designed to be more intuitive and perceptually relevant than the Cartesian RGB coordinate system. As shown, in the color space  4800 , hue is represented by the angular dimension, with the red primary commonly situated at angle 0, the green primary at 120°, and the blue primary at 240°. The radial dimension represents saturation, ranging from zero saturation (achromatic) at the center to fully saturated (pure colors) at the outside edge. The vertical axis represents lightness, ranging in the center from black (at lightness=0) to white (at lightness=1). 
     The HSV color space is only one possible color space that could be used to generate the color histogram. Some embodiments use a different color space, such as the HSL (hue-saturation-lightness) color space, YCbCr (luminance-chroma) color space, or other developer-defined color spaces. Other embodiments do not perform a color conversion, and just use the device&#39;s gamma-corrected RGB space in which the pixels are already defined. 
     With the pixel values converted, the process  4700  then identifies (at  4730 ) the region of HSV color space to which the currently selected pixel belongs. Each region is a three-dimensional region in the color space. However, in some embodiments, the regions have different sizes in the color space so that each region covers a similar volume of human-differentiable color space. That is, in areas of the color space where the human eye has trouble differentiating between different color values, the regions are larger as compared to areas of the color space where the human eye easily differentiates between different color values. 
     For instance, two regions might have different hue ranges, different saturation ranges, and/or different value ranges.  FIG. 49  illustrates a circular cross section  4900  of the HSV color space (i.e., at a constant value), with two regions defined. The first region  4905  is in the red portion of the hue dimension, while the second region  4910  is in the blue portion of the hue dimension. In general, the human eye can more easily differentiate between shades of blue than shades of red, so some embodiments use regions with smaller hue ranges in the blue portion of color space than in the red portion of the color space, as shown in this example. 
       FIG. 50  illustrates a three-dimensional portion  5000  of the HSV color space divided into two regions  5005  and  5010 . In this case, the saturation and hue of the two regions are equal, but the value range is different. One of ordinary skill in the art will recognize that these regions are merely examples, and that the regions may have any arbitrary shape in the color space. While not shown in either  FIG. 49  or  FIG. 50 , within a particular hue and value, multiple regions could be defined for different saturation ranges. Furthermore, the regions need not be of constant ranges in all dimensions. For instance, a particular region might have a first hue range at its outer saturation and a second, different hue range at its innermost saturation, so long as the regions account for the entirety of the color space. 
     Returning to  FIG. 47 , the process  4700  calculates (at  4735 ) a texture value for the currently selected pixel by comparing the pixel to neighboring pixels within the image. Some embodiments use a texture calculation that compares a pixel&#39;s brightness values to those of the surrounding pixels to determine a single texture value for the pixel. To determine the pixel brightness, some embodiments perform a calculation on the RGB pixel values. Other embodiments compare a different property of the pixel (other than brightness) to that of the neighboring pixel. 
     The novel texture calculation algorithm used by some embodiments is described by reference to  FIG. 51 . This figure illustrates nine pixels used by some embodiments to calculate the texture for the center pixel (P0). Initially, some embodiments calculate an intensity value (similar to a brightness, luminance, or value) for each pixel. This is essentially a weighted average of the RGB values, which may give more weight to one or the other color channel values. For instance, some embodiments place more weight on the red color channel. 
     The pixels in  FIG. 51  have intensity values of I 0  (for pixel P0) through I 8  (for pixel P8). The texture calculation of some embodiments uses a set of condition checks to determine a texture value. One of ordinary skill will recognize that the texture values do not correspond to a physical quantity, but rather are simply different bins. The texture calculation of some embodiments is as follows:
         if P0 has the largest intensity in the window, assign a texture of 0 to P0;   if P0 has the smallest intensity in the window, assign a texture of 1 to P0;   if P0 does not have either the smallest or largest intensity, but I 0 , I 1 , . . . I 8  are all within a threshold of each other (i.e., they all have same or similar intensities), assign a texture of 2 to P0.       

     If none of these three conditions are satisfied, the application computes the following differences:
 
( I   1   +I   2   +I   3 )−( I   6   +I   7   +I   8 );
 
( I   3   +I   5   +I   8 )−( I   1   +I   4   +I   6 );
 
( I   1   +I   2   +I   4 )−( I   5   +I   7   +I   8 );
 
( I   2   +I   3   +I   5 )−( I   4   +I   6   +I   7 ).
 
     The application then determines which of these differences has the greatest absolute value, as this is indicative of the direction of greatest intensity change within the window around the pixel P0. The first difference corresponds to vertical change in intensity, the second difference to horizontal change in intensity, the third difference to change from top right to bottom left, and the fourth difference to change from bottom right to top left. 
     If the first inequality is the largest, the application assigns one of the following two texture values:
         if (I 1 +I 2 +I 3 )&gt;(I 6 +I 7 +I 8 ), assign a texture of 3 to P0;   if (I 1 +I 2 +I 3 )&lt;=(I 6 +I 7 +I 8 ), assign a texture of 4 to P0.       

     If the second inequality is the largest, the application assigns one of the following two texture values:
         if (I 3 +I 5 +I 8 )&gt;(I 1 +I 4 +I 6 ), assign a texture of 5 to P0;   if (I 3 +I 5 +I 8 )&lt;=(I I +I 4 +I 6 ), assign a texture of 6 to P0.       

     If the third inequality is the largest, the application assigns one of the following two texture values:
         if (I 1 +I 2 +I 4 )&gt;(I 5 +I 7 +I 8 ), assign a texture of 7 to P0;   if (I 1 +I 2 +I 4 )&lt;=(I 5 +I 7 +I 8 ), assign a texture of 8 to P0.       

     Finally, if the fourth inequality is the largest, the application assigns one of the following two texture values:
         if (I 2 +I 3 +I s )&gt;(I 4 +I 6 +I 7 ), assign a texture of 9 to P0;   if (I 2 +I 3 +I s )&lt;=(I 4 +I 6 +I 7 ), assign a texture of 10 to P0.       

     Thus, the application assigns each pixel to one of the eleven different texture bins, based on the inequality. One of ordinary skill will recognize that while this example shows a 3×3 pixel window, some embodiments will use a 5×5 window, with each inequality having ten pixel intensities on either side rather than three. 
     With the texture for the selected pixel calculated, the process  4700  then identifies (at  4740 ) the texture range to which the pixel belongs. As texture is a one-dimensional value, each bin of the texture histogram represents a particular range along that one dimension. As with the color histogram, the different texture ranges may not necessarily be of equal length. 
     The process  4700  also calculates (at  4745 ) the gradient value by identifying the direction of greatest change in the neighboring pixels. Some embodiments use a gradient calculation that identifies the direction and amount of change in a pixel&#39;s intensity both horizontally and vertically. For instance, some embodiments use a gradient that measures only the relative intensity change (i.e., the vertical change compared to the horizontal change). Some embodiments use the formula that the gradient Θ=a tan 2 (δI/δy, δI/δx), where I is again the intensity (the same values used for the texture calculation given above). 
     Referring again to  FIG. 51 , the gradient for P0 is Θ=a tan 2 (I 2 −I 7 , I 4 −I 5 ). The a tan 2 function is a function that gives, for any real arguments (y, x) that are not both equal to zero, the angle in radians between the positive x-axis of the Cartesian plane and the point given by the coordinates (x, y) on the plane. Thus, the gradient of some embodiments is an angle that relates to the relative difference between the vertical intensity change and the horizontal intensity change. 
     With the gradient calculated, the process then identifies (at  3850 ) the gradient range to which the pixel belongs. The gradient given above is a one-dimensional value (i.e., just an angle). In some embodiments, the gradient is a two-dimensional value (represented, e.g., as an x-y vector or an angle and length). Thus, each bin of the gradient histogram represents a particular range of x and y gradient values. As with the color histogram, different gradient ranges may not necessarily be of equal size in the Cartesian x-y space. 
     With the ranges identified for the three different properties of the pixel, the process adds (at  4755 ) the pixel to the color, texture, and shape (gradient) histograms for each tile of the image to which the pixel belongs, as determined at operation  4720 . As indicated, for the tiling scheme shown in the above figures, this may be three different histograms, six different histograms, or twelve different histograms, depending on the location of the pixel. 
     Having analyzed the currently selected pixel, the process  4700  determines (at  4760 ) whether any additional pixels in the image remain unanalyzed. When additional pixels remain, the process  4700  returns to operation  4715  to select the next pixel. Once all of the pixels have been analyzed, the process ends. 
       FIG. 52  conceptually illustrates the software architecture of portions of the image viewing, editing, and organization application of some embodiments that generate histograms and compare images for similarity.  FIG. 52  illustrates a histogram generation module  5200 , a similarity comparator  5250 , and an image selector  5275 . In addition, this figure illustrates image data  5280  (i.e., the image data structures and image files stored by the application) and collection data  5285  (i.e., the collection data structures stored by the application). 
     The histogram generation module  5200  receives an image (e.g., an image that the image viewing application is importing) and generates color, texture, and shape histograms for various regions of the image, then stores these histograms with the image. The histogram generation module  5200  includes an image tiler  5205 , an HSV converter  5210 , an intensity calculator  5215 , a texture calculator  5220 , a gradient calculator  5225 , and a histogram generator  5230 . 
     As shown, the image tiler  5205 , the HSV converter  5210 , and the intensity calculator  5215  receive image data. The image tiler  5205  receives an image, identifies the dimensions of the image, and calculates the coordinates in the image (i.e., the pixel coordinates) for the different regions for which the histogram generation module  5200  will generate histograms. The image tiler  5205  passes these tile coordinates to the histogram generator  5220 . 
     The HSV converter  5210  receives the pixel data for an image and converts each pixel into the HSV color space (e.g., from RGB space). One of ordinary skill will recognize that different embodiments may use different versions of the RGB to HSV conversion, or may use a different color space entirely. The HSV converter passes this color space data for each pixel of the image to the histogram generator  5220 . 
     The intensity calculator  5215  also receives pixel data for the image and calculates the intensity value for each pixel. As with the HSV converter, different embodiments may use different calculations to derive the intensity from the RGB pixel values. The intensity calculator  5215  provides this intensity data to the texture calculator  5220  and the gradient calculator  5225 . 
     The texture calculator  5220  calculates a texture value for each pixel (e.g., using the texture algorithm described above, or a different process) and provides these values to the histogram generator  5220 . The gradient calculator  5225  calculates a gradient value for each pixel (e.g., using the gradient algorithm described above, or a different process) and provides the gradient values to the histogram generator  5220 . 
     The histogram generator  5220  uses the color data, texture values, and gradient values to generate histograms for each of the tiles received from the image tiler  5205 . The histogram generator  5220  receives, e.g., a texture value for each pixel. For a particular pixel, the histogram generator identifies, based on the pixel coordinates, to which (possibly more than one) of the tiles the pixel belongs. The generator then adds the texture value to the appropriate bin of the histogram for the one or more tiles. The histogram generator  5220  stores these histograms in the image data  5280  for the image. 
     The similarity comparator  5250  identifies images similar to a particular user-selected image. As shown, the similarity comparator  5250  includes a comparison score generator  5255  and a threshold checker  5260 . When a user requests similar images for a particular image, the similarity comparator  5250  receives a list of images from the collection data  5285  (e.g., a list of the images in a particular collection). The similarity comparator  5250  retrieves the histograms for the images and calculates one or more comparison scores for each pair of images. 
     The threshold checker  5260  receives the comparison scores and determines whether each pair of images qualifies as similar. The threshold checker, as described above, may perform various different checks on the different scores (in some embodiments, there are 27 different comparison scores). The threshold checker  5260  outputs the list of similar images to the image selector  5275 , which manages the selection of the particular images for the GUI. 
     B. User Selections of Multiple Images 
     As mentioned, some embodiments provide various other methods for selecting multiple images in order to simultaneously view the selected images. For example, the application may operate on a multi-touch capable device (i.e., a device capable of recognizing multiple different points of contact with a touchscreen, touchpad, etc.) and translate multi-touch input over the thumbnail display area into a block selection of thumbnails. Furthermore, some embodiments allow users to press and hold thumbnails in order to add the thumbnail to a set of selected images. 
       FIG. 53  conceptually illustrates a process  5300  of some embodiments for selecting a block of thumbnails within the image display area. In some embodiments, the application receives a multi-touch selection in order to select this block.  FIG. 53  will be described by reference to  FIGS. 54 and 55 , which illustrate examples of the selection of such blocks of thumbnails. Both of these figures illustrate three stages of a GUI  5400 , which includes a thumbnail display area  5405  and an image display area  5415 , similar to the corresponding display areas in the GUIs described above. The first stage  5410  of  FIG. 54  and the first stage  5510  of  FIG. 55  both illustrate the GUI  5400  with no images selected. 
     As shown, the process  5300  begins by receiving (at  5305 ) two separate and at least partly coincidental selections within the thumbnail display area. The application may receive these selections from the touchscreen of a device capable of translating multi-touch inputs. For instance, a user might use two fingers to press down on two separate thumbnails in the thumbnail display area. Because users are unlikely to make an initial contact with a touchscreen at the exact same time with two fingers, some embodiments only require that the inputs be partially coincidental. 
     The process then identifies (at  5310 ) a first thumbnail in the thumbnail display area associated with the first touch selection and (at  5315 ) a second thumbnail associated with the second touch selection. Some embodiments associate each thumbnail with a particular two-dimensional array of screen pixels, which changes as the thumbnails scroll through the display area. When a user touches the screen over the thumbnail grid, this touch input is translated into a set of pixel values (e.g., a circle of a particular radius, a square with a particular side length, etc.). The application then compares these pixel values to those of the thumbnails in order to determine which thumbnail the user is selecting. Some embodiments identify the thumbnail that corresponds to the greatest portion of the touch input pixels. 
     The second stage  5420  of  FIG. 54  illustrates a user tapping a first thumbnail  5425  with her index finger and a second thumbnail  5435  with her thumb. Assuming that the top left thumbnail represents the first image in the collection, these are the third and eighth thumbnails in the ordered collection of images. In the second stage  5520  of  FIG. 55 , the user taps a first thumbnail  5505  (the fourth thumbnail in the ordered collection) and the same second thumbnail  5435 . 
     With the boundary thumbnails for the selection identified, the process  5300  determines (at  5320 ) whether the first thumbnail is before the second thumbnail in the display area. The order may be determined from an order value in the collection data structure (e.g., an array index of the reference to the image data structure that stores the thumbnail) or relative order may be derived from the screen pixels to which the thumbnails are displayed. 
     Some embodiments use the first input received as the first thumbnail and the second input received as the second thumbnail. However, in order to define the selection properly, the application needs the first thumbnail to come before the second thumbnail in order. As such, when the first thumbnail is after the second thumbnail, the process switches (at  5325 ) the first and second thumbnails so that the first thumbnail comes first in the order. 
     Next, the process selects (at  5330 ) all images with thumbnails in the grid from the first thumbnail to the second thumbnail. For instance, in  FIG. 54 , thumbnails three and eight are the first and second thumbnails. As such, all of thumbnails three through eight will be selected by this user action. Similarly, in  FIG. 55 , thumbnails four through eight will be selected. 
     The process then displays (at  5335 ) a selection indicator on the selected thumbnails. Some embodiments use two different forms of selection indicator to indicate whether a selected thumbnail corresponds to a secondary selected image (i.e., one of several selected images) or a primary selected image (i.e., an active image that is the only image shown in the image display area). 
     Accordingly, the process  5300  also displays (at  5340 ) the selected images in the image display area. When multiple images are selected in block form with process  5300 , some embodiments always display all of the images in the image display area. In some embodiments, the application displays all of the images using a same visual weighting by using an approximately equal number of pixels for each of the images. The process of some embodiments for identifying the ideal display will be described below in subsection C of this section. 
     The third stages  5430  of  FIG. 54 and 5530  of  FIG. 55  illustrate the resulting display of the respective multi-touch block selections. In stage  5430 , all six thumbnails from thumbnail  5425  to thumbnail  5435  are displayed with a thin highlight. In addition, the application displays the six images in the image display area with equal size. Stage  5530  illustrates the same result with one fewer thumbnail selected. Because the application only displays five images in the image display area  5415 , two of the images are displayed centered along the bottom row, but have the same size as the other images displayed along the top row. As is apparent from these two images, some embodiments display the images in the image display area in the order that the thumbnails are shown in the thumbnail display area (which, in turn, is the order the images are stored in the collection data structure). 
     In addition to the multi-touch block selection, some embodiments allow users to press and hold a thumbnail in order to select the thumbnail as one of a group of selected images. When the user merely taps a thumbnail, that causes the selection of the corresponding image to be the sole selected image. On the other hand, when the user holds down the input (e.g., presses down on the touchscreen for a threshold duration), the application maintains selection of any previously-selected images and adds the thumbnail to the set of selected images. 
       FIG. 56  conceptually illustrates a process  5600  of some embodiments for translating user input over an unselected thumbnail into a selection of the thumbnail. Users may also tap or press and hold an already-selected thumbnail (which may be the primary selection or a secondary selection), and these inputs are described below by reference to  FIG. 66 . In addition, while this process is described as responding to touchscreen input, one of ordinary skill in the art will recognize that some embodiments implement a similar process for non-touchscreen input (e.g., with mouse clicks instead of taps and the press and hold of a mouse button instead of pressing and holding on a touchscreen).  FIG. 56  will be described by reference to  FIG. 57 , which illustrates various selection inputs in the GUI  5400  over six stages  5710 - 5760 . 
     As shown, the process  5600  begins by receiving (at  5605 ) a single touch input within the thumbnail display area over an unselected thumbnail. In some embodiments the application has a single process for resolving all input over the thumbnail display area. In other embodiments, the application receives the multi-touch information from the touchscreen device in a form that gives an input type (e.g., tap, hold, swipe, etc.) and a screen location. The application then resolves this event (input and location) into an action to take (e.g., select item, slide display area, perform edit, etc.) based on its current state. However, this conceptual process deals only with the receipt of a single touch input (i.e., either a tap or a hold) over an unselected thumbnail in the thumbnail display area. 
     The process then identifies (at  5610 ) an unselected thumbnail associated with the touch input. As described above by reference to  FIG. 53 , some embodiments associate each thumbnail with a particular two-dimensional array of screen pixels, which changes as the thumbnails scroll through the display area. When a user touches the screen over the thumbnail grid, this touch input is translated into a set of pixel values (e.g., a circle of a particular radius, a square with a particular side length, etc.). The application then compares these pixel values to those of the thumbnails in order to determine which thumbnail the user is selecting. Some embodiments identify the thumbnail that corresponds to the greatest portion of the touch input pixels. 
     The process then determines (at  5615 ) whether the input has been removed from the touchscreen. In this conceptual process, the application is left to make the determination between a tap and a hold, while the touchscreen device provides the application with the basic data that a particular portion of the touchscreen is receiving a touch input. As mentioned, in some embodiments, the difference between a tap and a hold is made at the device level (e.g., by a framework within the operating system of the device), and the application would actually have several different event-driven processes for dealing with these different inputs. 
     When the input has not yet been removed from the touchscreen, the process determines (at  5620 ) whether the input has been present for a threshold duration. This duration is the length of time that a user has to maintain contact with the touchscreen in order for the input to qualify as a press and hold rather than a tap. When the threshold duration for a hold has not yet been reached, the application returns to  5615 . In essence, these two operations form a determination between a tap (if the process determines that the user has removed the input from the touchscreen before the threshold duration is reached) and a hold (if the duration is reached with the input still present). As stated, some embodiments receive this determination from a framework of the device on which the application operates. 
     When the input is removed from the touchscreen before the threshold duration, the process selects (at  5625 ) the identified thumbnail and removes (at  5630 ) the selection of any other thumbnails. That is, the application makes the identified thumbnail the only selected thumbnail. The process then displays (at  5635 ) the image associated with the thumbnail as the sole image in the image display area. The process then ends. 
     The first stage  5710  of  FIG. 57  illustrates the GUI  5400  with a first image displayed in the image display area  5415  and its corresponding thumbnail  5705  highlighted as the primary selection. As shown, at this stage the user selects a thumbnail  5715  with a tap input. The second stage  5720  illustrates that the result of this tap selection is that the application now highlights the thumbnail  5715  as the primary selection, with the thumbnail  5705  no longer highlighted. In addition, the image  5717  corresponding to thumbnail  5715  is displayed in the image display area  5415 , as this is the only selected image. 
     Returning to  FIG. 56 , when the input is present over the thumbnail for the threshold duration, the application selects (at  5640 ) the identified thumbnail. The application then displays (at  5645 ) the image associated with the thumbnail along with any other selected images. That is, one or more images might have already been selected, and the application displays all of these images in the image display area. The process then ends. 
     The second stage  5720  shows a user selecting a thumbnail  5725  with a press and hold selection (indicated by the small clock icon, which is shown conceptually and is not part of the GUI). As a result, in the third stage  5730  the application displays both the image  5717  and the image  5727  (which corresponds to the thumbnail  5725 ). Furthermore, both the thumbnail  5715  and the thumbnail  5725  are highlighted as selected. However, the application uses a lighter selection indication highlight, in order to indicate that both of these thumbnails are secondary selections and that there is no primary selection at this time. The two images  5717  and  5727  are displayed in such a way as to maintain the aspect ratio (i.e., without distorting or cropping the image) and maximize the image size, as will be explained below in subsection C. 
     The third stage  5730  also illustrates that the user again performs a press and hold selection, this time over the thumbnail  5735 . In stage  5740 , the application adds the image  5737  to the image display area, rearranging the other images in the display area as needed. Furthermore, the thumbnail  5735  is now highlighted with a secondary selection highlight, the same as the other two thumbnails. 
     In addition, the user performs a multi-touch block selection at this stage, tapping thumbnails  5745  and  5755 . As shown in stage  5750 , this causes the selection of the thumbnail  5765  in addition to the two tapped thumbnails. As a result, in stage  5750 , six thumbnails are now highlighted with the lighter selection indication, and the corresponding six images are displayed in the image display area. The application has reduced the size of these images as compared to the previous stages in order to fit six images into the display area with the same visual weighting. 
     At stage  5750 , the user taps an unselected thumbnail  5775 . Stage  5760  illustrates the result of this selection, with the image  5777  displayed on its own in the image display area. The selection of the other six thumbnails is removed, and the application displays a thicker selection indication highlight on the thumbnail  5775 . 
       FIG. 58  illustrates a similar set of selection operations in the mobile phone and media player GUI  1700  of some embodiments. The first stage  5810  illustrates the user making a tap selection of a thumbnail  5805 , resulting in the display of the corresponding image in the display area  1715 . The second stage  5820  illustrates a press and hold selection of the thumbnail  5815 , so that the corresponding image is then added to the image display area. Next, the user makes a simultaneous tap selection of the thumbnails  5825  and  5835 , so that the images corresponding to these thumbnails as well as the thumbnail  5845  in between them are all added to the image display area. 
     C. Displaying Multiple Images 
     The above subsections described different actions available in some embodiments in order to select multiple images for simultaneous display in the image display area. As described briefly, when displaying multiple images within the image display area, some embodiments maintain the aspect ratio of each of the images while also giving each image the same visual weight (e.g., number of screen pixels). 
       FIG. 59  conceptually illustrates a process  5900  of some embodiments for displaying multiple images simultaneously within an image display area.  FIG. 59  will be described by reference to  FIGS. 60-65 , which conceptualize the calculations performed by some embodiments in order to display four images that have different aspect ratios with the same visual weighting. 
     As shown, the process  5900  begins by receiving (at  5905 ) N images to display in the image display area. In this case, N is a non-zero positive integer (i.e., 1, 2, 3, etc.). When there is only a single image, some embodiments do not perform the process  5900 , although the process does produce a correct result of the one image displayed at full size. These images may be received through any of the user interactions described in the above subsections (e.g., a block selection, a request to identify similar images, or other selections that result in the selection and display of multiple images), as well as any other interactions not described herein. 
       FIG. 60  illustrates a GUI  6000  with a user making a block selection of four thumbnails. The GUI  6000  includes an image display area  6005 , which is shown in the expanded view as having a 4:3 aspect ratio. In some embodiments, the image display area will vary in size (i.e., number of pixels) and aspect ratio depending on the resolution and screen aspect ratio of the display screen of the device on which the GUI is displayed, the size of the thumbnail display area, whether other GUI areas occupy portions of the display, etc. 
     Upon receiving the command to display the images in the image display area, the process calculates (at  5910 ) the average aspect ratio of the received images. This average aspect ratio is used as the aspect ratio for a set of regions in the image display area into which the images will be fit. As  FIG. 61  illustrates, the four selected images  6105 - 6120  have aspect ratios of 4:3, 3:4, 16:9, and 4:3. Images  6105  and  6120  have the same aspect ratio, but different sizes. In many cases, the images will all have a resolution (i.e., number of defined pixels) larger than the number of screen pixels available, especially when multiple images are displayed. Thus, each image is allocated a smaller portion of the screen. The average aspect ratio of the images  6105 - 6120  is [(4/3)+(3/4)+(16/9)+(4/3)]/4=187/144, as shown by the region  6125 . 
     The process  5900  then divides (at  5915 ) the image display area into a number of rows and columns that maximizes the screen area per image for at least N images with the calculated average aspect ratio. As the display regions will all have the same dimensions, the most efficient way to pack in the regions will be in grid form. Thus, if there are five images, the grid of regions might be a 3×2 grid, a 2×3 grid, or if the images are extremely elongated a 1×5 or 5×1 grid. 
     In order to identify the optimal solution, some embodiments test through the space of possible row/column combinations that can be used to hold the N images in order to determine which combination gives the maximum possible area per region with the average aspect ratio. Some embodiments begin with one column and iterate up to the number of images to display (though some embodiments put a cap on the number of columns). 
     For a particular number of columns, the application determines the number of rows needed to display all of the images. For example, for three columns and five images, two rows will be needed, though one of the regions would not be used. The application then calculates the width of a maximally sized region for the particular number of columns and rows as the total width of the viewing area divided by the number of columns (possibly subtracting out a constant to ensure that there will be at least a small gap between images in the display). The application also calculates the height of the maximally sized region as the total height of the viewing area divided by the number of rows (again, possibly subtracting out a constant). The application then determines the dimensions of a region having the average aspect ratio that fits within this maximal region. The number of columns used is that which maximizes the area of this region. 
       FIG. 62  illustrates that the ideal number of columns for the 187:144 aspect ratio region  6125  within the 4:3 image display area  6005  is two, with two rows. In fact, because 187:144 is very close to 4:3, this grid nearly fills the total area. 
     Next, the application calculates (at  5920 ) the area available to each of the images based on the number of rows and columns. This calculation, in some embodiments, is the maximally sized region used to determine the number of rows and columns in operation  5915  as described in the prior paragraphs. In the example, this area is the area of the region  6125  within the image display area  6005 . 
     The application then identifies (at  5925 ) the image that will have the smallest area when fit into the available area (i.e., the size of the grid regions). This will generally be the image having an aspect ratio that differs the most from the average aspect ratio. In some embodiments, to identify this image, the application calculates the height and width of each image in order to maintain the image&#39;s aspect ratio and fit the entire image within the grid region. For images with a larger aspect ratio than the average, the width will equal that of the grid region while the height will be reduced from that of the grid region. For images with a smaller aspect ratio than the average, the height will equal that of the grid region while the width is reduced from that of the grid region. 
       FIG. 63  illustrates the different aspect ratio images within the grid region  6125 . The 4:3 image  6105  occupies 97% of the grid region (and the other 4:3 image  6120  occupies the same portion), the 16:9 image  6115  occupies 73% of the grid region, and the 3:4 image  6110  occupies 58% of the grid region. Accordingly, the image  6110  is identified as that with the smallest area when fit into the grid region. Accordingly, in order for each image to use the same number of pixels, each image will occupy 58% of the grid region area. 
     The process then calculates (at  5930 ) the width and height for each image in order to maintain the aspect ratio and use the same area within the grid region as the image with the smallest area, as determined at operation  5925 . For a particular image, some embodiments calculate the width as square root of the product of the minimum area and the aspect ratio of the image. The height of the particular image is then calculated as the width divided by the aspect ratio. 
       FIG. 64  illustrates the sizes of the images  6105  (which is equivalent in size to image  6120 ) and  6115  when fit to occupy the same area in the image display area as the image  6110 . Both of these images are sized down to only occupy 58% of the region  6125 . To use example numbers, if the region  6125  has a width of 374 pixels and a height of 288 pixels, then the size of image  6105  for display would be approximately 288 pixels×216 pixels. The size of image  6115  would be approximately 333 pixels×187 pixels. The size of image  6110 , shown in  FIG. 63 , would be approximately 216 pixels×288 pixels. 
     The process  5900  assigns (at  5935 ) each of the images to their region in the display area. The application, in some embodiments, takes the images in order (e.g., their order within the thumbnail display area, which in turn is determined by their order within the collection) and assigns them to grid regions. In addition, when some of the grid regions in the last row are not used, the application removes these grid regions and centers the grid regions of the bottom row. 
     Finally, the process displays (at  5940 ) the images within the image display area in the assigned regions at the assigned size.  FIG. 65  illustrates the images  6105 - 6120  displayed within the image display area  6005 . As can be seen, the images all appear (e.g., to a human observer) to be the same size, because they each have the same number of pixels. This gives the beneficial result that none of the images appear more preferable in a comparison of the images simply on account of being larger than the other images. As a common use of the multiple image display feature is for a user to determine which of several photos of the same scene to keep, having images appear the same size provides a significant benefit to the user. 
     V. Operations on One or More Images 
     The above Section IV describes various techniques available in some embodiments in order to select one or more images, including automatically identifying groups of similar images, block selections of thumbnails, and pressing and holding thumbnails in order to add the corresponding image to a group of selected images. The following section describes various operations that may be used in order to apply tags to images, cycle through images in a selection, as well as select and deselect individual images. 
     A. Selection and Deselection Operations 
       FIG. 66  conceptually illustrates a state diagram  6600  that describes different states and transitions between these states of the GUI of some embodiments relating to the selection/deselection of images and viewing of selected images. One of ordinary skill in the art will recognize that the GUI of some embodiments will have many different states relating to all different types of input events, and that the state diagram  6600  is specifically focused on a subset of these events. The state diagram  6600  will be described in part by reference to  FIGS. 67-71 , which illustrate various selection and deselection operations. The state diagram  6600 , as well as the accompanying figures, describe and illustrate touch interactions for changing states of the GUI. One of ordinary skill in the art will recognize that various other interactions, such as cursor controller gestures and button clicks, keyboard input, or touchpad/trackpad input may also be used for similar selection operations. Within the figure, many of the transition conditions are shown as user interactions (e.g., “swipe left”). One of ordinary skill in the art will recognize that the state transitions occur in response to the receipt of such user input by the image viewing and editing application. 
     When only one image is selected, the GUI is in state  6605 , displaying the single selected image in the image display area and displaying a primary selection indicator on the corresponding thumbnail. As shown in the previous section, some embodiments use a primary selection indicator on thumbnails to indicate when only one image is displayed in the image display area, while also using a secondary selection indicator on thumbnails to indicate when the thumbnail is one of multiple selected images. In some embodiments, both selection indicators are highlights around the border of the thumbnail, with the primary selection indicator being a thicker highlight than the secondary selection indicator. 
     With one image selected, users can select a different image by tapping on an unselected thumbnail. When a user taps an unselected thumbnail (in this case, any other thumbnail than the one that corresponds to the displayed image), the application transitions to state  6607  to set the tapped thumbnail (and its corresponding image) as the new selected image, then transitions back to state  6605 . In addition, users can cycle through the images with left and right swipe gestures. As shown, when the application receives a rightward swipe gesture, the application transitions to state  6608  to set the previous image in the collection as the new selected image. Similarly, when the application receives a leftward swipe gesture, it transitions to state  6609  to set the next image in the collection as the new selected image. After either such change, the application transitions back to  6605 , with the new selected image displayed in the image display area. When receiving one of these swipe gestures, some embodiments use a slide animation to show the previously selected image sliding off the display with the new selected image either sliding onto the display (from the right side if a leftward gesture, and from the left side if a rightward gesture). Other embodiments use other animation to illustrate the change in image, or just replace the image in the image display area without any animation at all.  FIG. 33  illustrates an example of such a swipe gesture to cycle through the images in a collection. 
     With the GUI in state  6605 , the user can add one or more images to the image display area. These may replace the currently selected image (e.g., if the user double taps on an unselected image to display all images similar to that image), or be added alongside the currently selected image (e.g., if the user presses and holds down over a thumbnail. When the user performs one of these actions to add one or more images to the preview display area, the GUI transitions to state  6610  and displays the multiple selected images in the image display area and displays secondary selection indicators on the corresponding thumbnail. Numerous examples of such a transition are shown in the above section (e.g.,  FIGS. 44, 54, 55, and 57 ). 
     Once in the state  6610  (with multiple images selected and displayed), if the user taps an unselected thumbnail, then the GUI transitions to state  6607  to set the tapped thumbnail as the only selected image and then back to state  6605 , as illustrated by stages  5750  and  5760  of  FIG. 57 . In addition, while in state  6610 , the user can press down and hold one of the thumbnails in the thumbnail display area. When the particular thumbnail is one of the previously selected thumbnails, the application transitions to state  6615  to remove the particular thumbnail from the set of selected thumbnails. If only one thumbnail remains selected, then the GUI transitions to state  6605  to display only the one selected image. Otherwise, the GUI transitions back to state  6610  to display the selected images, which no longer include the particular thumbnail. In addition, if the user performs a downward swipe gesture over a particular image in the image display area, then this will have the same effect of removing the particular image from the selected set. On the other hand, as shown in the previous section, when the particular thumbnail is presently unselected, then the application transitions to  6617  to add the image corresponding to the thumbnail to the current set of selected images, then transitions back to  6610  with an additional image shown in the image display area. Stages  5730  and  5740  of  FIG. 57  illustrate such an operation. 
     In addition, from state  6610 , when the user taps one of the selected thumbnails or one of the displayed images in the image display area, the GUI transitions to state  6620 . At state  6620 , the application displays a single active image in the preview area with a primary selection indicator on its corresponding thumbnail and a secondary selection indicator on the thumbnails corresponding to the other selected images.  FIG. 67  illustrates this transition over two stages  6710  and  6720  of a GUI  6700 . The GUI  6700  includes a thumbnail display area  6705  and an image display area  6715 . At the first stage  6710 , the GUI displays three images  6725 - 6735  in the image display area  6715 , with the corresponding thumbnails  6740 - 6750  highlighted in the thumbnail display area  6705 . 
     Also in the first stage  6710 , the user taps the image  6730 . The second stage  6720  illustrates the result of this interaction, with the image  6730  occupying the entirety of the image display area  6715 . Furthermore, the thumbnail  6745  that corresponds to the image  6730  now is bordered by a heavier highlight than the thumbnails  6740  and  6750 , which remain selected. Some embodiments animate this transition. For instance, in some embodiments, the application displays the image expanding from its position among multiple displayed images into the larger image that uses the full image display area in at least one direction. In addition, while the second stage  6720  of  FIG. 67  illustrates the image  6730  occupying nearly the entire image display area, in some embodiments the application displays a faded, darker version of the other selected images behind the primary displayed image. When the primary displayed image does not occupy portions of the image display area (e.g., because of differences in aspect ratio between the image and the display area), portions of the other selected images (in the faded, darker form) will be visible within the display. 
     In the following discussion, the primary selected image will be referred to as the active image, while all of the images in the selection, whether the primary selection or one of the secondary selections, will be referred to as selected. With the GUI in state  6620 , the user can perform various actions to cycle through the images (e.g., if comparing various photos to identify the best of a set). As shown, when the application receives a swipe right gesture over the image display area, the GUI transitions to state  6625  to set the previous selected image in the collection order as the new active image, before transitioning back to the state  6620  to display the new active image. Some embodiments animate this transition; for instance, by minimizing the previously active image back into its position in the image display area (i.e., the location the image would occupy if all selected images were displayed at once) while expanding the new active image into its larger display. 
     Other embodiments use various forms of a sliding animation. In some embodiments, the application slides this new active image onto the display while sliding the previous active image off. In other embodiments, the new active image appears to be underneath the previous active image, so that more of the image appears as the previous image slides off. Still other embodiments slide the new active image onto the display over the old active image. In some embodiments, the choice of how the application displays this transition is left up to the user. 
       FIG. 68  illustrates a series of such rightward swipe gestures in the user interface  6700  over five stages  6810 - 6850 . The first stage  6810  illustrates the GUI  6700  in the same state as stage  6720  of  FIG. 67 . As shown, the user has begun to contact the touchscreen with one finger. In the next stage  6820 , the user has started sweeping her finger to the right, causing the image  6730  to slide to the right off of the screen and revealing the image  6725  below. The result of this swipe gesture is shown in stage  6830 , with the image  6725  now displayed in the image display area  6715 . In addition, the corresponding thumbnail  6740  is now bordered with a thick highlight, indicating the primary selection, while the other selected thumbnails are bordered with a thinner highlight. 
     In addition, at this stage, the user again contacts the touchscreen, and the fourth stage  6840  illustrates that the user makes another swipe gesture to the right. This causes the image  6725  to slide to the right off of the screen, revealing the image  6735  below. The result of this swipe gesture is shown in stage  6850 , with the image  6735  now displayed in the image display area  6715 . In addition, the corresponding thumbnail  6750  is now bordered with the thick highlighting of the primary selection indicator, while the other selected thumbnails are bordered with a thinner highlight. 
     Similar to the swipe right gesture, when the application is in state  6620  and receives a swipe left gesture over the image display area, the GUI transitions to state  6630  to set the next selected image in the collection order as the new active image, before transitioning back to the state  6620  to display the new active image. Some embodiments animate this transition; for instance, by minimizing the previously active image back into its position in the image display area (i.e., the location the image would occupy if all selected images were displayed at once) while expanding the new active image into its larger display. 
     Other embodiments use various forms of a sliding animation. In some embodiments, the application slides this new active image onto the display while sliding the previous active image off. In other embodiments, the new active image appears to be underneath the previous active image, so that more of the image appears as the previous image slides off. Still other embodiments slide the new active image onto the display over the old active image. In some embodiments, the choice of how the application displays the cycling through the images is left up to the user. 
       FIG. 69  illustrates such a leftward swipe gesture in the GUI  6700  over three stages  6910 - 6930 . The first stage  6910  illustrates the GUI  6700  in the same state as stage  6850  of  FIG. 68 , with the image  6735  as the active image in the image display area and its corresponding thumbnail  6750  selected with a heavy highlight. As shown, the user has begun to contact the touchscreen with one finger. In the next stage  6920 , the user has started sweeping her finger to the left, causing the image  6735  to slide to the left off of the screen and revealing the image  6725  below. The result of this swipe gesture is shown in stage  6930 , with the image  6725  now displayed in the image display area  6715 . In addition, the corresponding thumbnail  6740  is now bordered with a thick highlight, indicating the primary selection, while the other selected thumbnails are bordered with a thinner highlight. 
     As these figures illustrate, in some embodiments the application will allow the user to cycle through a set of selected images with the sweep gestures, including swiping from the last image in the set to the first image in the set, rather than preventing a swipe gesture in one direction once the user reaches the end of the set. 
     In addition to cycling through a set of selected images in response to users swiping left and right, some embodiments also allow users to remove images from the set via a swipe gesture. As shown in the state diagram  6600 , when the application receives a swipe down gesture while in state  6620 , the GUI transitions to state  6635  to remove the active image from the set of selected images and set the next image in the set of selected images as the new active image. Much like the right and left swipe gestures, in some embodiments the application animates the transition; e.g., by minimizing the previously active image while expanding the new active image into the larger display. 
     Other embodiments use various forms of sliding animation; In some embodiments, the application slides the new active image onto the display while sliding the previous active image off the bottom of the display. In other embodiments, the new active image appears to be underneath the previous active image, so that more of the image appears as the previous image slides off. Still other embodiments slide the new active image onto the display over the old active image. In some embodiments, the choice of how the application displays this transition is left up to the user. 
     When there were only two images in the set of selected images, a swipe down will leave only one selected image, in which case the GUI transitions back to state  6605  with the single selected image displayed in the image display area. On the other hand, when at least two images remain selected after removing the active image, then the GUI returns to the state  6620  with the next image in the set as the active image. For the selected images, some embodiments of the application recalculate their size and location in the image display area and display the faded, darker versions of the inactive selected images in their new positions behind the active image. 
       FIG. 70  illustrates such a downward swipe gesture in the user interface  6700  over three stages  7010 - 7030 . The first stage  7010  illustrates the GUI  6700  in the same state as stage  6930  of the previous figure, with the image  6725  as the active image in the image display area and its corresponding thumbnail  6740  selected with a heavy highlight. As shown, the user has begun to contact the touchscreen with one finger. In the next stage  7020 , the user has started sweeping her finger downwards, causing the image  6725  to slide downwards off of the screen and revealing the image  6730  below. The result of this swipe gesture is shown in stage  7030 , with the image  6730  now displayed in the image display area  6715 . In addition, the corresponding thumbnail  6745  is now bordered with a thick highlight, indicating the primary selection, while the thumbnail  6740  is no longer highlighted as it has been deselected. 
     As shown, in some embodiments, the user pressing and holding the thumbnail of the active image has the same effect of causing the GUI to transition to state  6635  to remove the active image from the set of selected images and set the next image in the set as the active image. In addition, when the user presses and holds a selected but inactive thumbnail (i.e., the corresponding image is not the image displayed), the application transitions to  6640  to remove the corresponding image from the set of selected images. As at stage  6635 , the application either transitions to state  6605  (if only the active image remains selected) or back to state  6620  (if multiple images remain selected). When the application transitions back to state  6620 , some embodiments of the application recalculate the size and location in the image display area of the images that remain selected and displays the faded, darker versions of the inactive selected images in their new positions behind the active image. 
     In addition, when the user presses and holds an unselected thumbnail, the application transitions to state  6617 , to add the corresponding image to the set of selected images. As shown, some embodiments also transition back to state  6610  when the user adds a new image to the set. On the other hand, some embodiments select the image but maintain the full-viewer display of the active image. 
     As illustrated in  FIG. 66 , with the GUI in state  6620 , when the user taps an unselected thumbnail, the application removes the selection of all of the other images and transitions to state  6607 , to set the newly selected image (corresponding to the tapped thumbnail) as the sole selected image. The application then transitions back to state  6605  to display the newly selected image in the image display area. When the user taps the active thumbnail, this causes the GUI to transition back to state  6610  with all of the selected images displayed in the image display area, removing the active designation from the image corresponding to the tapped thumbnail. Finally, some embodiments allow the user to switch the active image between different images in the set by tapping a selected thumbnail that corresponds to one of the inactive images. As shown, when the user taps a selected but inactive thumbnail, the application transitions to state  6645  to set the image corresponding to the tapped thumbnail as the new active image, then transitions back to state  6620 . 
       FIG. 71  illustrates examples of a user tapping on the selected thumbnails in the GUI  6700  over four stages  7110 - 7140 . The first stage  7110  illustrates the GUI  6700  in the same state as the first stage  6710  of  FIG. 67 , with the three images  6725 - 6735  all displayed in the image display area and their corresponding thumbnails  6740 - 6750  selected with a lighter highlight. 
     Also in this stage  7110 , the user taps the touchscreen over the thumbnail  6740 . The second stage  7120  illustrates the result of this interaction, with the corresponding image  6725  now the active image occupying the entirety of the image display area  6715 . In addition, the thumbnail  6740  that the user tapped is now displayed as bordered with a heavier highlight than the other selected thumbnails. 
     At this stage  7120 , the user taps the touchscreen over the thumbnail  6745 . The third stage  7130  illustrates the result of this interaction, with the corresponding image  6730  now the active image occupying the entirety of the image display area  6715 . In addition, the thumbnail  6745  that the user tapped is now displayed as bordered with a heavier highlight. These stages illustrate that whether the GUI is in state  6610  or state  6620 , tapping a selected but not active thumbnail will make the corresponding image the active image. 
     In addition, at stage  7130 , the user again taps the thumbnail  6745  of the active image. The result of this interaction is shown in stage  7140 , with the application again displaying all three images  6725 - 6735  with no active image, and therefore no primary selection indicator for any of the thumbnails. This pair of stages illustrates the transition from state  6620  to state  6610 , with multiple images displayed at once. 
     B. Tagging Images 
     The above section describes various selection and deselection operations performed with one or more images in the image-viewing application of some embodiments. The state diagram  6600  included three primary selection states  6605 ,  6610 , and  6620 . In some embodiments, the images to which the application applies a user-selected tag depend on which of these three states the GUI is in when the user selects the tag.  FIG. 72  conceptually illustrates a state diagram for the GUI of some embodiments relating to the application of a tag in these three different states.  FIG. 72  will be described by reference to  FIGS. 73-77 , which illustrate the application of different tags to one or more images. 
     As shown, the state diagram illustrates the states  6605  (only one image selected),  6610  (multiple images selected and displayed), and  6620  (multiple images selected, only active image displayed), as well as transitions between these states (described above by reference to  FIG. 66 ). In addition,  FIG. 72  displays the states resulting from the selection of a tag UI item in these three different states. As mentioned above by reference to  FIG. 14 , some embodiments include a set of GUI items for applying different tags to one or more images. These tags may include a favorites tag (i.e., to indicate an image that the user especially likes), a flag (i.e., to indicate an image that the user wants to review again later), and a hide tag (i.e., to remove an unwanted image from the set of images shown in the thumbnail display area). These tags, in some embodiments are stored with the data structure for the tagged image, and may be used to populate specific albums for images with that tag. 
     As shown in  FIG. 66 , when the GUI is in state  6605  and the user selects a tag to apply to an image, the GUI transitions to state  7205  to apply the selected tag to the sole currently selected image. The GUI then transitions back to the state  6605 . In some embodiments, when the tag is a hide image tag, the GUI also removes the image from display and selects the next image in the collection to select and display. Other embodiments do not immediately remove a hidden image from the display, instead waiting for the user to first view a different image. 
     When the GUI is in state  6610  and the user selects a tag to apply, the GUI transitions to state  7210  to apply the selected tag to all of the currently selected images. The GUI then transitions back to the state  6610 . Lastly, when the GUI is in state  6620  and the user selects a tag to apply, the GUI transitions to state  7220  to apply the selected tag to only the active image rather than all of the currently selected images. The GUI then transitions back to the state  6620 . 
       FIGS. 73-78  illustrate the application of various tags to images within the image viewing application of some embodiments.  FIG. 73  illustrates the application of the hide image tag over four stages  7310 - 7300  of a GUI  7300 . The GUI  7300  includes an image display area  7305  and an image display area  7315 , in addition to various sets of GUI items. These GUI items include a flag button  7325 , a favorites button  7332 , and a hide image button  7335 . 
     In the first stage  7310 , an image  7342  is displayed in the image display area  7315  and the corresponding thumbnail  7345  is selected. At this stage, the user selects the hide image button  7335 , causing the button to become highlighted. In some embodiments, the application animates the application of the hide tag to an image. The second stage  7320  illustrates the animation used by some embodiments to indicate the application of the hide image tag to the image in the image display area. A hide image icon  7350  (an X) is shown as coming out of the image, then receding back into the image (i.e., to become a property of the image). 
     The third stage  7330  illustrates that the application marks the corresponding thumbnail  7345  of the hidden image  7342  with a hide icon  7355  (an X) overlaid on the thumbnail. In addition, at this stage, the user selects a different thumbnail  7360 . The fourth stage  7340  illustrates that the image corresponding to the thumbnail  7360  is now displayed. In addition, the application has removed the thumbnail  7345  of the hidden image from the thumbnail display area  7305  and rearranged the thumbnails in the display area accordingly. As shown, in some embodiments, the application waits until the user has navigated to a different thumbnail to remove the hidden thumbnail from the displayed set of thumbnails. 
       FIG. 74  illustrates the application of a flag image tag over four stages  7410 - 7440  of a GUI  7400 . The GUI  7400  includes the same features as the GUI  7300 —a thumbnail display area  7405 , an image display area  7415 , and the various GUI items, including the flag button  7425 . In addition, the GUI includes a tag filtering button  7435 , which currently indicates that none of the fifteen images in the currently selected collection are tagged. This button  7435 , in some embodiments, is used to identify which images in a collection the application should present within the thumbnail display area. At the moment, three images are selected (corresponding to thumbnails  7445 - 7455 ), but only one of the selected images (the image  7460 ) is displayed in the image display area. 
     At the first stage  7410 , the user selects the flag button  7425 , causing the button to become highlighted. In some embodiments, the application animates the application of the flag images tag to an image. Furthermore, as indicated above by reference to  FIG. 66 , when multiple images are selected and one of the selected images is active, the application applies tags to only the active image (in this case, the image  7460 ). 
     The second and third stages  7420  and  7430  illustrate the animation used by some embodiments to indicate the application of the flagged tag to the image in the image display area. The flag icon  7465  is shown as coming out of the active image, then receding back into the image (i.e., becoming a property of the image). 
     In the fourth stage  7440 , the application displays a small flag icon  7470  over the thumbnail  7445 , to indicate that this image is flagged. When displaying thumbnails in the thumbnail display area, some embodiments check the image data structure for the images in the collection in order to determine whether the images have any tags. If the flagged tag is present for the image, then the application displays the flag over the image&#39;s thumbnail. The flag button  7425  remains highlighted to indicate that the currently active image is flagged. In some embodiments, users can select the flag button when in this state in order to unflag the active image. In addition, at this stage, the tag filtering button  7435  now indicates that one of the fifteen images in the collection has been flagged. 
       FIG. 75  illustrates the application of the flag image tag to multiple images over four stages  7510 - 7540  of the GUI  7400 . As shown, at the first stage  7510 , a flag icon  7470  is displayed over the thumbnail  7445 . The image display area, however, displays three selected images  7505 ,  7515 , and  7525 , and the thumbnails corresponding to these images are selected. At this stage, the user selects the flag button  7425 . As indicated above by reference to  FIG. 66 , when multiple images are displayed in the image display area, the application applies tags to all of these selected images. In some embodiments, the application animates the application of the flag images tag to the images. 
     The second and third stages  7520  and  7530  illustrate the animation of some embodiments to indicate the application of the flag image tag to the images in the image display area. The application displays multiple instances of the flag image tag, with one instance shown coming out of each displayed image, then receding back into the image (i.e., becoming a property of the image). 
     In the fourth stage  7540 , the application now displays a small flag icon  7570  over each of the thumbnails  7535 ,  7450 , and  7455 , to indicate that the images  7505 ,  7515 , and  7525  are flagged. The flag button  7425  remains highlighted to indicate that the currently displayed images are all flagged. In addition, the tag filtering button  7435  now indicates that four of the fifteen images in the collection have had the flag tag applied. 
       FIG. 76  illustrates the use of the tag filtering button  7435  over three stages  7610 - 7630  of the GUI  7600 . In the first stage  7610 , the button  7435  indicates that four of the fifteen images are flagged, and the application displays flag icons over the four thumbnails  7445 ,  7535 ,  7450  and  7455 . An unflagged image  7605  is currently displayed in the image display area, and therefore the application does not highlight the flag button  7425 . In the first stage  7610 , the user taps the button  7435 . 
     As shown in the second stage  7620 , this causes the display of a menu  7615 . This menu allows the user to select between different sets of images within the selected collection based on the tags applied to the images. The options, as shown, are “All Photos” (which, in some embodiments, does not include the hidden photos), “Flagged Photos”, “Edited Photos”, “Hidden Photos”, and “All &amp; Hidden Photos”. The flagged, edited, and hidden photos options cause the display of only images with those tags, while the all and hidden photos option makes the hidden images viewable along with the rest of the collection. 
     In the second stage  7620 , the user selects the “Flagged Photos” option. The third stage  7630  illustrates the result of this selection, with the application displaying only the thumbnails  7445 ,  7535 ,  7450 , and  7455  for the flagged images. Essentially, the application applies a filter to the images in the collection, with only the images that have the flagged tag making it through the filter. The application also now displays the image  7460 , which is one of the tagged images, in the image display area. 
       FIG. 77  illustrates the application of the favorites tag to an image over four stages  7710 - 7740  of the GUI  7300 , which is described above by reference to  FIG. 73 . In this case, the image  7705  is active as one of two selected images. At the first stage  7710 , the user selects the favorites button  7332 , causing the button to become highlighted. In some embodiments, the application animates the application of the favorites tag to an image. Furthermore, as indicated by reference to  FIG. 66 , when multiple images are selected and one of the selected images is active, (as is the case in this figure), the application applies tags to only the active image. 
     The second and third stages  7720  and  7730  illustrate the animation used by some embodiments to indicate the application of the favorites tag to the image in the image display area. The favorites icon  7715  is shown as coming out of the active image, then receding back into the image (i.e., becoming a property of the image). 
     In the fourth stage  7740 , the favorites button  7332  remains highlighted to indicate that the active image is a favorite. As with the flagged image tag, users can select the favorites button when in this state in order to remove the favorites tag from the active image. In some embodiments, the application does not display an icon over the thumbnails to indicate which images are favorites (as shown in this figure). However, as will be described below, the application does keep a separate collection of favorite images and adds images tagged with the favorites tag to this collection. 
     In some embodiments, the application prevents an image from being tagged with both the favorites tag and the hide image tag. When a user selects the favorites button for an image tagged as hidden, the application applies the favorites tag while also removing the hide image tag. Similarly, when a user hides a favorite image, the application removes the favorites tag from the image. 
       FIG. 78  illustrates the application of the favorites tag to multiple images over four stages  7810 - 7840  of the GUI  7800 . As shown, at the first stage  7810  the application displays the images  7805 ,  7815 , and  7825  in the image display area, with the corresponding thumbnails selected. At this stage, the user selects the favorites button  7332 . As indicated above by reference to  FIG. 66 , when multiple images are displayed in the image display area, the application applies tags to all of these selected images. In some embodiments, the application animates the application of the favorites images tag to the images. 
     The second and third stages  7820  and  7830  illustrate the animation of some embodiments to indicate the application of the favorites tag to the images in the image display area. The application displays multiple instances of the favorites tag, with one instance shown coming out of each displayed image, then receding back into the image (i.e., becoming a property of the image). In the fourth stage  7340 , the favorites button  7332  remains highlighted to indicate that the selected images are marked as favorites. As in the above figure, the thumbnail display is not affected by the favorites tag. 
     As mentioned with reference to the favorites tag, some embodiments create separate collections for some or all of the tags that the application can apply to the images. In some embodiments, only a favorites collection is created, while other embodiments create collections for favorite images, flagged images, hidden images, and edited images, or some combination thereof. 
       FIG. 79  conceptually illustrates a process  7900  performed by the application of some embodiments upon receipt of a tag to apply to an image. As shown, the process  7900  begins by receiving (at  7905 ) a selection of a tag to apply to one or more images. In some embodiments, the selection of a tag may occur by the user selecting one of the tagging buttons (e.g., to flag an image, hide an image, or mark the image as a favorite) or by editing a previously unedited image. 
     The process then adds (at  7910 ) the selected tag to the data structures for the images. As shown above in  FIG. 15 , the data structure for an image stored by the application of some embodiments includes fields for any tags applied to the image. In some embodiments, to apply the tag the application switches the value of a variable for the particular tag from 0 to 1. 
     The process then determines (at  7915 ) whether a collection of images with the selected tag already exists. In some embodiments, the application does not create empty collections, and thus, e.g., the favorites album does not exist until at least one image has been marked as a favorite. Other embodiments, however, always store collections for each possible tag irrespective of whether the application has at least one image or is empty. 
     When the collection for the selected tag already exists, the process adds (at  7920 ) the newly tagged images to the previously existing collection of images with the particular tag. In some embodiments, the images are added to the collection at the end of the ordered series of images for the collection. In other embodiments, the application stores an overall order for the images (e.g. their order within the All Photos collection, and this order is maintained within the tagged images collection). 
     On the other hand, when the collection does not yet exist for the particular tag, the process  7900  creates (at  7925 ) a new collection for the tagged images. The process then adds (at  7930 ) the newly tagged images to the new collection. In some embodiments, the application creates a new collection data structure for the particular tag, with a name such as “Favorites”. The application then adds references to the image data structures for the newly tagged images to the newly created data structure. In some embodiments, the different collections of tagged images appear as albums. 
       FIG. 80  illustrates a user navigating from an album to the collection of favorite images over three stages  8010 - 8030  of the GUI  7300 . In the first stage  8010 , the application displays the image  7705 , to which the favorites tag has been applied, as indicated by the highlighted favorites button  7735 . Also at this stage, the user selects the back button  8005 . 
     As a result, the second stage  8020  illustrates that the application now displays a collection organization GUI  8000 , with the albums tab  8015  highlighted. The application currently stores two albums, “Album 1” and the Favorites album. As shown, the user selects the Favorites album at this stage. The third stage  8030  illustrates the GUI  7300  with the Favorites as the selected collection. As only four images have been marked as favorites, the collection only includes these four images. In some embodiments, when a user views the favorites album, selects an image, and then selects the (highlighted) favorites button, the application not only removes the favorites tag from the selected image, but also removes the image from the favorites collection and no longer displays the image (such that the tag functions like a hide image tag for the specific collection). 
     C. Viewing Image Information 
     In some embodiments, a user may wish to view information about one or more images. Some embodiments provide a GUI item (or provide a keyboard shortcut, a menu option, etc.), the selection of which causes the image viewing application to present information about the image. In some embodiments, the application stores this information in the data structure for the image or uses information from the data structure to access the displayed information. When multiple images are selected and displayed in the image display area, some embodiments display separate information for each of the selected images, while other embodiments display only the information that all of the selected images have in common. 
       FIG. 81  illustrates the access of such information in the GUI  7300  for an image  8105  over three stages  8110 - 8130  according to some embodiments of the invention. As shown, at the first stage  8110 , the application currently displays the image  8105 . In the second stage  8120 , the user selects the information button  8115 . 
     The third stage  8130  illustrates the information window  8125  that appears when the user selects the information button  8115 . As shown, the window  8125  has three tabs: an info tab, a map tab, and a comments tab. The info tab displays information about the selected image, primarily using Exif data. When the image has GPS data, the user can select the map tab in order to view a map showing the location at which the image was captured. In some embodiments, the application uses the GPS data to access a database of map data and downloads a particular region of map data around the GPS location. This database may be either a database local to the device running the application or a remote database accessed through a network, such as the Internet. The comments tab, as will be described below in Section VI, can be used to view others&#39; comments on the image when the image has been uploaded to a social media or photo sharing website, as well as make additional comments on the shared image. 
     Within the info tab, the application of some embodiments displays the device with which the image was captured (Canon EOS-1Ds Mark III), the type of image file used to store the image data (JPEG), the resolution (3072×4608) and file size (2.6 MB) of the image, the time and date the image was captured (Mar. 4, 2012 at 12:10:17 PM), and the location at which the image was captured (Joshua Tree National Park). In some embodiments, the location is automatically resolved based on GPS data, while in other embodiments the user enters this data. At the bottom of the window  8125 , the application displays camera settings information, including the aperture (f/5.6), shutter speed (1/200), focal length (180 mm), exposure (0.7 EV), and film speed (ISO 200). 
       FIG. 82  illustrates a user accessing information for an image  8205  in the GUI  7300  over three stages  8210 - 8230  according to some embodiments of the invention. With the exception of the different image  8205  in the image display area, the first two stages  8210  and  8220  are the same as shown above for  FIG. 81 . In the third stage, the information window  8125  displays different values for the information, as some of it differs from that of image  8105 . For example, the timestamp (3:15:57 PM) is later on the same day, and the file size as well as some of the camera settings are different. 
       FIG. 83  illustrates the selection of the information window with both of the images  8105  and  8205  selected over three stages  8310 - 8330  of the GUI  7300 . Again, the first two stages of the figure are similar to those of the previous two figures, except that in this case the application displays both images  8105  and  8205  in the image display area. In the third stage  8330 , the information window  8125  only displays information that all of the selected images have in common. In this case, the images are both JPEG files with 14.2 MP, but have different file sizes (which are therefore not shown). Furthermore, both of the images&#39; GPS data resolves to Joshua Tree National Park, and while the timestamps are different, both images were captured on March 4 (at different times). In the image settings, the shutter speed, focal length, and film speed settings were the same for the two images, but because the photographer had different settings between the two images for the aperture and exposure compensation, the application does not display this information. 
     VI. Sharing Images 
     As briefly mentioned in the previous section, some embodiments allow the user to share images directly from the image editing, viewing, and organizing application by uploading the images to a social media or photo sharing website through the user&#39;s account on the site. When the user requests to share the image, the application instructs the device on which it operates to connect to the website (e.g., through the Internet), then automatically uploads it to the user&#39;s account on the website. In some embodiments, the application additionally identifies when other users of the website have commented on the image, and displays these comments to the user of the application. 
     Some embodiments provide the functionality for a user to add a caption to the image. When a user wants to share an image on a photo hosting website, the user may wish to have a caption with the image. In some embodiments, the user can add this caption within a dialog for sharing the image to the website, in addition to or as an alternative to using the caption stored for the image within the application. Within the application, this caption is stored in the data structure for the image, as shown in  FIG. 15  above.  FIG. 84  illustrates a user adding a caption to an image over six stages  8410 - 8460  of a GUI  8400 . The GUI  8400  is similar to the previous GUIs (e.g., GUI  3500 ), but also includes an add caption button  8405  at the center of the top toolbar. In the first stage  8410 , the application displays a selected image  8415  in the image display area. 
     In the second stage  8420 , the user taps the add caption button  8405  in order to add a caption to the selected image  8415 . The third stage  8430  illustrates that the application overlays a touchscreen keyboard  8425  over some or all of the touchscreen in order for the user to enter a caption. In some embodiments, the keyboard is provided by the operating system of the device, and the application sends a request for the keyboard to the operating system when the user provides the input to add a caption. 
     In addition, in some embodiments the touchscreen device can be connected to a separate keyboard that the user may use to enter the caption. Furthermore, one of ordinary skill in the art will recognize that the image viewing application might operate on a non-touchscreen device with which the user interacts using a cursor controller (or other device) in order to select the add caption button and then a keyboard to type in the caption. 
     The third and fourth stages  8430  and  8440  illustrate the GUI  8400  as the user types in a caption “In the Front Row!” for the image  8405 . As the user types, the caption appears in the upper header area above the image display area. In the fifth stage  8450 , the user selects the “return” button on the keyboard in order to complete the caption. The sixth stage  8460  illustrates the GUI  8400  after the user has entered the caption. The application now displays the caption atop the image instead of the add caption button. In addition, the application overlays the caption in small text over the thumbnail  8435  The application will now have stored the entered caption with the data structure for the image  8415 . 
     As stated, whether or not an image has a caption, in some embodiments a user can use the image viewing and editing application to upload the image to a social media or photo sharing website.  FIG. 85  illustrates user interaction with the GUI  8400  in order to share the image  8405  via the social media site Facebook® according to some embodiments. In the first stage  8510 , the user selects the sharing button  8505 , which provides options for sharing selected images in a variety of manners. As shown in the second stage  8520 , the application displays a sharing menu  8515  with the options to beam the image, create a journal using selected images, and share the image on the Internet. In some embodiments, beaming an image entails directly sharing the image with another device on the same local network (e.g., a Bluetooth network, a Wi-Fi network, etc.). A journal, in some embodiments, is a shareable arrangement of a set of images to which users can add text notes, graphics, and other information. 
     In the second stage  8520 , the user selects the “Share on Internet” option. The third stage  8530  illustrates that the application now displays a new menu  8525  with three photo sharing website options (Twitter®, Flickr®, and Facebook®), although other embodiments may include different websites to which users can share images. In this example, the user selects the Facebook® option in order to share the image to their Facebook® account. At this point, the application begins attempting to upload the image to the user&#39;s Facebook® account. 
     In some embodiments, the different social media/photo sharing websites are part of the menu  8515 , along with creating a journal, beaming an image, and various other sharing options. In addition, after a user selects the website with which to share the image, the application then provides options for the user to choose which images (i.e., the selected image or images, all the images in the current album, a new set of images from the current album, etc.) to upload to the photo sharing website. 
       FIG. 86  conceptually illustrates a process  8600  of some embodiments for sharing an image via a social media or photo sharing website. While  FIG. 86  refers to a “photo sharing” site, this could be a site specifically designed for photo sharing, such as Flickr®, or a broader social media website such as Facebook® or Twitter®. As shown, the process  8600  begins by receiving (at  8605 ) a command to upload an image to a photo sharing website. The application may receive this command through the set of user interactions shown in  FIG. 85 , or through a variation thereof. 
     The process then determines (at  8610 ) whether a user account is logged onto the selected photo sharing site from the device on which the application operates. Some embodiments of the application operate on a device that includes specific applications for different social media and photo sharing sites through which the device automatically logs on to the website as necessary. In this case the application will not have an issue with logging onto the website. In other embodiments, the user has to affirmatively log on (either through an site-specific application or through a web browser) to the sites. 
     When the user is not logged on, the process  8600  prompts (at  8615 ) the user to sign in to the website before uploading the image, then ends. Once the user logs on, the application again begins the process  8600 . In some embodiments, the image viewing application displays an interface through which the user logs on to the website, while other embodiments require the user to switch to a different application (e.g., a dedicated application for the site or a web browser) in order to log on. 
     When the user has logged on to the requested photo sharing site, the process determines (at  8616 ) whether the image has already been uploaded to the site. In some embodiments, the application checks the data structure for the image to determine whether an image ID is already stored for the image for the particular photo-sharing website. In addition, some embodiments determine whether the image still exists on the website, by querying the website database. Some embodiments perform this check for some websites but not others. 
     When the image is already shared, the process  8600  then determines (at  8619 ) whether the user wants to share the image as a new image. The user might want to add the image to a different album within the photo-sharing website. In addition, the user might have edited the image, and wants to add the edited image as a new image (e.g., to show the image both before and after editing. When the user adds the image as a new image, the process proceeds to  8620 , described below. Otherwise, the process also determines (at  8617 ) whether the user wants to replace the uploaded image on the photo sharing site. For instance, the user might have edited the image and wants to replace the shared image with the new version. To implement operations  8619  and  8617 , some embodiments provide a prompt to the user that allows the user to choose whether to cancel an upload, share an image as a new image, or replace the existing version of the image on the photo-sharing site. When the user does not want to replace the image or share a new image, the process ends without uploading the image. 
     When the user wants to replace a shared image, the process uploads (at  8618 ) the new image through the interface of the photo sharing site using the existing image ID for the image to be replaced, then ends. When the image is not yet shared, then the process uploads (at  8620 ) the image through the interface of the photo sharing site. In some embodiments, the image viewing and editing application uses the site-specific application (e.g., a Facebook® application) on the device to perform the upload operation. In other embodiments, the application transacts with the website itself. In order to upload the image, some embodiments generate a full-size image with the edit instructions applied (as described above, some embodiments store only the original full-size image along with edit instructions for generating an edited image from the original). 
     After uploading the image through the interface of the photo sharing site, the process  8600  receives (at  8625 ) an ID for the uploaded image in the database of the photo sharing site. The process stores (at  8630 ) the image ID for use in accessing the image on the web site, then ends. This image ID enables the application to contact the website and request information about the uploaded image (e.g., in order to download the comments). In some embodiments, the application stores the image ID in the image data structure, as shown above by reference to  FIG. 15 . 
     In the process  8600  of some embodiments, when the user chooses to upload an image, the application automatically uploads the image to the photo-sharing website without any further interaction. However, some embodiments allow the user to further customize the upload.  FIGS. 87A-87C  illustrate a user uploading an image to Facebook® over ten stages  8701 - 8710  of the GUI  8700 . The GUI  8700  is similar to the previously shown GUI  8400  of some embodiments, including a sharing button  8705 . The first stage  8705  illustrates that the user has already selected the sharing button  8715 , causing the application to display a menu of various different sharing options. In this case, the menu includes several icons, for various different photo-sharing/social media websites, as well as creating a journal. In some embodiments, this menu includes additional sharing options such as beaming the image to another device, e-mailing the image, etc. As shown, the user selects the “Facebook” icon at stage  8701 . 
     The selection of this option causes the application to display an additional menu  8720  in the GUI  8700  at the second stage  8702 . This menu  8720  allows the user to determine which images should be shared. The user can select to share the entire album currently displayed in the thumbnail display area, the presently selected images, or a third option to select new images, which in some embodiments brings up a dialog box through which the user can select a set of images from the current album (or different albums, in some such embodiments) for sharing. In this case, the user chooses to share the one selected image. 
     In the third stage  103 , the GUI  8700  now includes an image-sharing dialog box  8725  that enables the user to customize the upload of an image to the particular selected photo-sharing website (in this case, Facebook®). The dialog box  8725  includes a thumbnail image  8730 , a caption box  8735 , an add location item  8740 , and a friend tagging item  8745 . In some embodiments, when a user shares multiple images, the application displays these items for each image selected for sharing. In addition, the dialog box  8725  includes a cancel option and a share option, enabling the user to cancel the sharing operation or begin actually uploading the images, respectively. Finally, the dialog box  8725  includes an album selection button  8750 , that enables the user to select between different albums on the photo-sharing website (as opposed to albums within the image viewing and editing application) as destinations for the shared images. As shown, in the third stage  8703 , the user selects the album selection button  8750 . 
     This selection results in the display of a menu (or picker)  8755  from which the user can select different albums in the fourth stage  8704 . In some embodiments, the application (or the device on which the application operates) logs into the user&#39;s account on the photo-sharing website (necessary to upload the images, as described above), and retrieves a list of the different albums the user has created on the website. When the user selects button  8750  (or its equivalent), the application displays a list of the user&#39;s albums, as well as an option to create a new album. Some embodiments pre-populate the picker with a particular number of the most recent albums that the user has either created or uploaded images to. In this case, the user selects the “Nature” album option, so that the photo of lightning will be uploaded to this album on Facebook®. 
     In the fifth stage  8705 , the user selects the add location item  8740 . As shown in the sixth stage  8706 , this selection results in the display of a menu (or picker)  8760  from which the user can select different locations with which to tag the image. In some embodiments, the application (or the device on which the application operates) retrieves a list of different locations with which the user has previously tagged images on the photo sharing website. As shown, the menu  8760  includes options to choose a previously created “Home” location, a new location, or the current location. In some embodiments, the image viewing and editing application, or another application on the device that operates the image viewing and editing application, uses a location detection mechanism (e.g., GPS) to identify the user&#39;s location, and then correlates this location with a list of places (e.g., a restaurant, address, etc.) within a particular distance (e.g., 1 kilometer, 1 mile, etc.) of the identified current location. In addition, some embodiments use the GPS data stored with the image (e.g., within the Exif data) to determine a location, and list places within a particular distance of the location at which the image was captured. The application then provides this as a current location option within the menu  8760 . Some embodiments pre-populate the picker with a particular number of the most recent locations with which a user has tagged images. In this case, the user selects the “Home” location tag. 
     In the seventh stage  8707 , the user selects the friend tagging item  8745 . As shown in the eighth stage  8708 , this selection results in the display of a menu (or picker)  8765  that lists the user&#39;s friends within the context of the photo sharing website. Various photo-sharing/social media websites allow users to have a network of friends, and some embodiments retrieve the list of these friends so that the user can tag their friends in images through the interface of the image viewing and editing application. Some embodiments pre-populate the picker with a particular number of the most recently tagged friends of the user. In some embodiments, the user can tag any number of friends that they would like to. However, in this example, the user does not tag any friends, but instead selects within the caption box  8735 . 
     The ninth stage  8709  illustrates that when the user selects within the caption box (e.g., by tapping) the application overlays a touchscreen keyboard  8770  in order for the user to enter a caption for the image. In some embodiments, the keyboard is provided by the operating system of the device, and the application sends a request for the keyboard to the operating system when the user taps within the caption box. In this case, the user has used the keyboard  8770  to type “Right outside my house!” within the caption box  8735 , and selects the “return” button on the keyboard in order to complete the caption. In the tenth stage  8710 , the user selects the share button in order to share the photo along with the caption. In some embodiments, this caption is used for the photo-sharing site, but is not stored with the image within the image viewing and editing application. 
     As described above by reference to  FIG. 86 , when a user selects an image for sharing to a photo-sharing website to which the image has previously been uploaded, some embodiments allow the user to either upload the image as a new image or replace the older image on the website. In addition, when replacing an image, some embodiments retrieve the caption, tags, and/or other information from the website in order for the user to update this accompanying information. 
       FIG. 88  illustrates a user selecting two images for upload to Facebook®, including an edited version of the image uploaded in  FIGS. 87A-87C , over four stages  8801 - 8804  of the GUI  8700 . The first two stages  8801  and  8802  are the same as stages  8701  and  8702 , except that in this case the photo of the lightning has been edited (as indicated by the toolbox icon overlaid on its thumbnail) and a second image is also selected. In addition, the photo of the lightning has an icon overlaying its thumbnail indicating that it is already shared to at least one photo-sharing website. 
     After the user chooses to upload the selected images, the application determines whether any of the images are already uploaded. The data structure for the images (e.g., as described by reference to  FIG. 15  above) indicates any locations to which the image is shared. Because one of the images selected in this example is already shared to Facebook®, the application displays a dialog box  8805  indicating that the photo has already been shared, and allowing the user to choose whether to replace the image, share the image (as a new image within the context of the photo-sharing website), or cancel the upload. In this case, the user chooses to replace the image. In some embodiments, however, the application only brings up the dialog box  8805  if the user attempts to upload the image to the same album of the photo-sharing website as the previous version. 
     As a result, in the fourth stage the application brings up an image-sharing dialog box  8810 . This is similar to the dialog box  8725 , but includes two separate sets of caption box, thumbnail, add location item, and friend tagging item. For the lightning bolt image, the application retrieves the caption and tagging information from the photo-sharing website and displays this information as editable within the dialog box  8810 . In this case, the caption and the location are displayed as editable information. 
     For images uploaded to photo-sharing websites, some embodiments automatically retrieve interactions with the images from those websites.  FIG. 89  conceptually illustrates a process  8900  of some embodiments for retrieving comments posted to an image on a photo sharing or social media website. The application of some embodiments performs the process  8900  when an image currently displayed in the image display area of the application&#39;s GUI has been posted to a photo sharing site. Some embodiments only perform the comment retrieval process after displaying the image in the display area for a set period of time (e.g., one second, five seconds, one minute, etc.). 
     As shown, the process  8900  begins by identifying (at  8905 ) that the currently displayed image has been posted to a photo sharing website. Some embodiments wait a particular time duration while displaying an image, then determine whether the image is shared anywhere. When the image is not shared, the process  8900  will not be performed. Furthermore, when the image has been shared to several different sites, some embodiments perform the process  8900  or a variation thereof for each site, or a subset of the sites. 
     The process  8900  retrieves (at  8910 ) the image ID used for the image in the database of the photo sharing website. The application retrieves this image ID from the data structure of the displayed image, in some embodiments. The process then sends (at  8915 ) a request for information relating to the image to the photo sharing site, using the retrieved image ID to identify the image in the site&#39;s database. In some embodiments, this image ID is an object ID that identifies an object created for the image in the site&#39;s database, and the application requests certain properties of that object. 
     In response to sending the request, the process receives (at  8920 ) a comment stream and any additional requested information from the photo sharing site. In some embodiments, the comment stream is received as a series of comments that each includes a user making the comment, the user&#39;s profile thumbnail, the comment text itself, and a timestamp. Other embodiments, however, receive and parse the tree structure of nested comments. In addition, for images posted on Facebook® or sites with similar features, some embodiments receive the number of “Likes” a posted image has received, as well as who liked the image. 
     With this information received, the process  8900  retrieves (at  8925 ) the last access date of the comment stream for the image. The retrieved date and time is the last time that the user viewed any comments for the image within the image-viewing application. If the user has not viewed any comments on the image after uploading the image, then the retrieved time will be that of upload. In some embodiments, whether the user has viewed the comments on the image directly through the photo sharing site does not affect the last access date. 
     The process then determines (at  8930 ) whether the retrieved last access date is earlier than the most recent comment in the comment stream. The process compares the last access date to the timestamp for the most recent comment, and determines which is earlier. When the last access date is earlier, the process displays (at  8935 ) a notification to the user that new comments are available. In some embodiments, the notification consists of a small icon, or badge, over the information button (used to access the comments). Some embodiments use a notification button that simply indicates that new comments are available, while other embodiments provide an indication (e.g., a number inside the icon) of the number of new comments. In order to determine the number of new comments, some embodiments compare the last access date to each successively older comment until reaching a comment prior to the last access date. After displaying the notification, if necessary, the process  8900  then ends. 
     Users can view these comments, in some embodiments, by accessing the comments tab in the information window. Through this window, some embodiments also allow users to respond with additional comments that are posted to the photo sharing website. 
       FIG. 90  illustrates a user posting such a comment through the information window over six stages  9010 - 9060  of the GUI  8400  of some embodiments. In the first stage  9010 , the application displays the image  8415 , which the user had previously captioned and posted to Facebook®. In addition, the application displays a small icon  9005  over the info button  8505 . This small icon indicates that the displayed image has received two new comments. Some embodiments use the same icon for different photo sharing websites, without differentiating between the different sites. Other embodiments use different icons for Facebook®, Flickr®, etc. (e.g., different colors, different icon shapes, etc.). 
     In the second stage  9020 , the user selects the info button  8505 . As in  FIGS. 81-83 , this causes an information window  9015  to appear over the display in stage  9030 . The user then selects the comments tab. The fourth stage  9040  displays the comments tab. As shown, the information window  9015  now displays the Facebook® comments that “Paul Smith” has written on the user&#39;s image. This figure shows the info tab initially displayed and the user then selecting the comments tab. However, some embodiments automatically display the comments tab in response to a user selecting the info button with a notification icon displayed, on the assumption that the user most likely wants to view the new comments. The information window  9015  is larger in stage  9040  than in stage  9030 , in order to display all of the comments. In some embodiments, rather than expanding, the information window  9015  stays the same size and automatically displays the comments with the first new comment at the top of the window, with the user able to scroll through the comment stream. 
     In stage  9040 , the comment stream also includes a section into which the user can enter a comment. The user taps this section, and the fifth stage  9050  illustrates a touchscreen keyboard  8425  that appears as a result. This allows the user to type a comment to post to Facebook® for the image. After the user types her response, the information window  8415  displays the new comment at the end of the comment stream in stage  9060 , indicating that the comment has been posted to Facebook®. In order to post user comments, the application transmits the user comment with the stored image ID to the photo sharing website along with the user information. In some embodiments, the application awaits a confirmation from the website before displaying the comment in the application GUI. 
     VII. Context-Sensitive Help 
     Some embodiments also include a context-sensitive help feature that provides indications for various user interface tools as to the function of the tool. In some embodiments, the application determines for which user interface features the help information should be provided based on the current active tools of the application. For instance, when a user selects a particular set of editing tools, the application removes some of the help information from the display while adding information specifically for the selected set of editing tools to the display. 
       FIG. 91  conceptually illustrates a state diagram  9100  of the GUI of some embodiments that presents various operations of the help feature. One of ordinary skill in the art will recognize that the state diagram  9100  does not encompass every state of the image viewing and editing GUI, or even every state related to the context-sensitive help feature, but instead only a subset of the help feature operations within the GUI. 
     The state diagram  9100  will be described by reference to the UI examples illustrated in  FIGS. 92-96 . Specifically,  FIG. 92  illustrates a GUI  9200  of the image editing application of some embodiments in multiple stages related to the appearance of a help icon.  FIGS. 93-96  illustrate the GUI  9200  over multiple stages relating to the activation and display of the help feature as the user performs various operations within the GUI. 
     As shown in  FIG. 91 , the state diagram  9100  begins when a user opens the image viewing, organizing, and editing application at state  9105 . As the application opens, it transitions to either state  9110  or state  9115 , depending on whether the help tool has previously been activated on the device on which the application operates. In some embodiments, the image editing application stores a parameter with two states (e.g., 1 or 0) on the device. Upon first being loaded on a device, the application initializes the parameter in a first state (e.g., 0). Once a user has activated the help tool on the device, the application switches the parameter to the other state (e.g., 1). This way, the application determines whether the help tool has been activated on the device by checking the parameter. 
     If the help tool has never been activated on the device (e.g., the parameter has a value of 0), then the GUI transitions to state  9110  upon the application opening, at which the application displays the help icon in a conspicuous manner different from other GUI items of the application. In some embodiments, the help icon is a selectable UI item, which a user can select to activate the help tool. Different embodiments of the help tool implement the conspicuous display of the help icon differently. For instance, some embodiments display the help icon in a conspicuous manner by using a blinking help icon, or an icon that appears as pulsating. The application displays the help icon as changing between a small first state and a larger second state—either blinking between the two, or expanding and contracting to switch between the two states. 
       FIG. 92  illustrates an example of the display of the help icon in a conspicuous manner in the GUI  9200  over three stages  9205 - 9215 . As shown, the GUI  9200  includes a thumbnail display area  9230 , an image display area  9245 , a menu bar  9240 , a UI control display area  9260 , and a tool bar  9235 . The menu bar  9240  includes a set of selectable UI items for invoking different sets of image editing tools, including a selectable UI item  9242  for invoking a set of image cropping tools, a selectable UI item  9244  for invoking a set of exposure adjustment tools, a selectable UI item  9246  for invoking a set of color adjustment tools, a selectable UI item  9248  for invoking a set of brush tools, and a selectable UI item  9278  for invoking a set of special effect tools. The UI control display area  9260  is for displaying different sets of UI controls when they are invoked. In this example, the UI control display area  9260  includes the default set of UI items for the image viewing GUI, including a selectable UI item  9262  for initiating an auto enhance operation on the image, a selectable UI item  9264  for initiating a rotate operation on the image, a selectable UI item  9266  for flagging the image, a selectable UI item  9268  for marking the image as favorite, and a selectable UI item  9270  for hiding the image. 
     The tool bar  9235  includes additional selectable items, including a selectable UI item  9232  for navigating back to the collection organization GUI, a selectable UI item  9250  (i.e., the help icon) for invoking the help tool, a selectable UI item  9252  for displaying invoking the information window for a displayed image, and a selectable UI item  9254  for toggling between original and edited versions of the displayed image. 
     In  FIG. 92 , the help tool has never been activated on the device, and therefore the application displays the help icon in a conspicuous manner. In this example, the application displays the help icon  9250  as throbbing, or pulsing. As shown, the help icon includes a question mark graphic. This question mark expands and contracts in order to create the pulsating appearance. At the first stage  9205 , the help icon has a large question mark that extends beyond the borders of the icon. 
     The second stage  9210  illustrates the GUI  9200  with the help icon  9250  at its smallest state. As shown, the help icon  9250  is no longer highlighted, as indicated by a small question mark on the icon that is completely enclosed by the border of the help icon  9250 . To get from the first stage  9205  to the second stage  9210 , the application quickly decreases the size of the question mark part of the icon. In some embodiments, the second stage  9210  occurs only within a very short period of time (e.g., 0.5 seconds) after the first stage  9205 . 
     The third stage  9215  illustrates the GUI  9200  after the application has again increased the size of the question mark in the help icon  9250  to its largest point, similar to at stage  9205 . In some embodiments, the time for the application to get from the first stage  9205  to the second stage  9210  is the same as the time to get from the second stage  9210  to the third stage  9215 . The application, in some embodiments, shrinks the size of the help icon, then quickly expands the size of the icon, and so on. In some embodiments, the application displays the help icon in this manner until the user has invoked the help feature at least once. 
     Referring back to  FIG. 91 , if the application determines that the help tool has been previously invoked on the device as the application opens, the help tool transitions to state  9115 , where the GUI displays the help icon in the same manner as other icons. That is, the help icon appears in a normal state, similar to that shown in the second stage  9210  of  FIG. 92 . 
     While at either state  9110  or state  9115 , when the application receives a selection of the help icon, the GUI transitions to state  9120 , to display help indicators for (i) constant GUI items and (ii) the currently selected level of user tools. The GUI items, in some embodiments, include different sets of user tools. For example, some embodiments include the default tools (auto-enhance, rotate, flag, favorites, hide) as a first set, and then various sets of editing tools (e.g., crop tools, exposure tools, color adjustment tools, brush tools, and special effects tools). When the default tools are shown in the GUI, some embodiments display help indicators for the default tools as well as for the various edit activation items (for activating the different sets of editing tools). When one of the sets of editing tools is activated, the application displays these tools in place of the default tools. If the help feature has been invoked, some embodiments do not display help indicators for the different edit activation items, and instead only display help indicators for the selected editing tools. In some embodiments, the constant GUI items include items that are always present in the GUI, irrespective of which items are selected. These items may include the toggle original button, the sharing button, the info button, and other GUI items. 
     In some embodiments, the application remains at state  9120  unless (1) the user selects a new set of editing tools, (2) the user moves one of the currently selected editing tools, or (3) the user selects the help icon to deactivate the help feature. When a user selects a new set of tools, the application transitions to state  9125  to modify the currently selected level of user tools, then transitions back to state  9120  to display help indicators for the new currently selected level of tools. 
       FIG. 93  illustrates an example of invoking the context-sensitive help tool and changing the selected set of user tools in the GUI  9200  over three different stages  9305 - 9315 . The first stage  9305  is similar to the first stage  9205  of  FIG. 92 , except that the image display area  9245  only includes a single image. The second stage  9310  illustrates the GUI  9200  after the user has activated the help tool. In some embodiments, the help tool can be activated by a selection of the help icon. As shown, the user has activated the help tool by tapping a finger on the help icon  9250 . As a result of the selection, the application overlays various help indicators over the GUI. These help indicators display short bits of explanatory information for various GUI items. 
     In the second stage  9310 , the application displays help indicators  9325  for the constantly displayed GUI items  9238 ,  9252 , and  9254  within the tool bar  9235 . These help indicators are labeled “Share” for the sharing button  9238 , “Image info” for the information button  9252 , and “Show Original” for the toggle original button  9254 , though various embodiments may use different descriptions for one or more of the items. In addition, some embodiments only display the help indicators for items that are selectable; when the user has not yet edited the displayed image, the toggle original button will have no effect and therefore some embodiments do not display its help indicator. Some embodiments display the help indicators for different items in the toolbar  9235  (e.g., the undo button). 
     The help tool also displays a set of indicators  9335  for the currently selected level of user tools (“Auto-Enhance”, “Rotate”, “Flag”, “Favorite”, and “Hide”). In addition, when at this level of tools (the default set of user tools, shown when none of the edit activation items have been selected), the application displays help indicators  9330  for the edit activation items  9242 ,  9244 ,  9246 ,  9248 , and  9278 , that indicate to the user the different editing options (“Crop”, “Exposure”, “Color”, “Brush Tool”, and “Special Effects”). As with the constantly present GUI items, different embodiments may use different descriptions for the same item, or have a different set of GUI items. In some embodiments, the sets of help indicators are selectable UI items. In such embodiments, when a user selects a help indicator, the application overlays more detailed information about the functions and operations of the corresponding GUI item. 
     Some embodiments display directions for use within the help indicators for some of the items. For instance, in some embodiments, the “Rotate” indicator includes further information, such as “Rotate 90°. Touch and hold for more options”. As shown, the help indicators that the application overlays at  9310  include an indicator  9365  for the zoom tool in the center of the image display area that gives directions on using the zoom tool and an indicator  9375  for the thumbnail display area describing different types of selection inputs. 
     The third stage  9315  of  FIG. 93  illustrates an example of the user selecting a new set of tools in the GUI  9200 . As shown in the third stage  9315 , the user has selected the selectable UI item  9244  in the menu bar  9240  for invoking a set of exposure adjustment tools. As a result, the application displays a set of exposure adjustment tools in the UI control display area  9260 , replacing the auto-enhance, rotate, and tagging UI items. The set of exposure adjustment tools includes a shadows adjustment tool  9340 , a set of contrast adjustment tools  9345  and  9350 , a brightness adjustment tool  9355 , and a highlights adjustment tool  9360 . As a result of the user selecting a new set of tools, the application overlays a new set of help indicators  9370  (“Black point &amp; Shadows”, “Contrast”, “Highlights”, “Contrast”, and “White point &amp; Highlights”) for the newly displayed set of tools while removing the help indicators  9330  for the various edit activation tools  9242 ,  9244 ,  9246 ,  9248 , and  9278 . The application also overlays the indicator  9380  within the image display area to indicate that the user can adjust the exposure data for the image by touching and dragging over the image itself. In addition, the help indicators  9325  for the share, image info, and toggle original buttons remain, irrespective of which set of GUI tools the user selects. 
       FIG. 94  illustrates another example of the modification of the help feature when the user selects a new set of tools within the GUI  9200  at two different stages  9405  and  9410 . The first stage  9405  is identical to the second stage  9310  of  FIG. 93 . As shown, the help tool has been activated, as indicated by the appearance of the sets of help indicators  9325 ,  9330 ,  9335 ,  9365 , and  9375  in the GUI  9200 . The second stage  9410  illustrates the GUI  9200  after the user has selected a new set of tools for display in the GUI  9200 . In this case, the user has selected the selectable UI item  9248  within the menu bar  9240  for invoking a set of brush tools. As such, the application displays the set of brush tools  9425  for invoking different image adjustment operations in the GUI  9200 . As a result of the user selecting a new set of tools, the help tools also displays a new set of help indicators  9430  for the new set of brush tools  9425 , while removing the set of help indicators  9330  for the different edit activation tools. 
     Returning to the stage diagram  9100  of  FIG. 91 , when the user moves one of the currently selected tools while the application is at state  9120 , the application transitions to state  9130  to move the help indicator along with the moving GUI tool. For instance, when the user moves a slider, that slider&#39;s help indicator moves along with it. 
       FIG. 95  illustrates an example of the application automatically moving a help indicator along with a corresponding edit tool at three stages  9505 - 9515 . The first stage  9505  is identical as the third stage  9315  of  FIG. 93 , with the help tool activated and the exposure adjustment tools selected. As shown, the application displays the set of help indicators  9370  for the set of exposure adjustment tools  9340 - 9360 . The second stage  9510  illustrates the GUI  9200  as the user begins to contact the touchscreen in order to move one of the exposure adjustment sliders. The third stage  9515  illustrates the movement of the contrast adjustment tool  9345  by the user. As a result of this movement, the help indicator  9370  (labeled “Contrast”) moves along with the tool to the right. In addition, moving one of the contrast tools causes the other contrast tool to move as well, and as such the other contrast slider  9350  moves to the left along with its help indicator. As a result of this movement, the contrast of the displayed image is modified. 
     Referring back to  FIG. 91 , when the user selects the help icon again after the help tool is activated, the help tool removes all the help indicators from the GUI. In addition, since the user has already activated the help tool on the device, the help tool returns to state  9115 , where the help tool displays the help icon in the same manner as other icons, as shown in stage  9305  of  FIG. 93 . 
     As mentioned above, when a user selects one of the help indicators, some embodiments display a detailed help article about the selected feature. Some embodiments either download these help articles from an external location (e.g., via the Internet) or store them with the application. 
       FIG. 96  illustrates an example of displaying a detailed help article related to one of the GUI items through the GUI  9200  through three different stages  9605 - 9610 . The first stage  9605  is identical to the first stage  9405  of  FIG. 94 , with the help tool activated, as indicated by the display of the help indicators for the GUI items shown on the GUI  9200 . When a user selects one of the help indicators, the application displays more detailed information about the functions and operations that are related to the corresponding GUI item. 
     The second stage  9410  illustrates the user selecting one of the help indicators. Specifically, the user selects (e.g., via a tap as shown, via a click selection, etc.) the help indicator for the crop item  9242 , causing the application to highlight the crop indicator. 
     As a result of the selection, the application overlays detailed help information  9630  for the crop tools over the GUI  9200  at stage  9615 . As stated, in some embodiments, the content of the detailed help information is stored on the device on which the image editing application is executed. In these embodiments, when the user selects a help indicator, the application retrieves the corresponding help information from the device before displaying the information on GUI  9200 . In other embodiments, the detailed help information is stored at one or more remote locations to which the device connects through a network (e.g., the Internet). In these embodiments, when the user selects a help indicator, the application retrieves the detailed help information from one of these remote locations through the network before displaying the information on GUI  9200 . 
       FIG. 97  illustrates another example of the display of help indicators for different GUI items in some embodiments. Specifically,  FIG. 97  illustrates the movement of help indicators as well as multiple levels of help indicators for color adjustment tools over four stages  9710 - 9740  of the GUI  9200 . The first stage  9710  is identical to the first stage  9405  of  FIG. 94 , with the help tool activated, as indicated by the display of the help indicators for the GUI items shown in the GUI  9200 . 
     The second stage  9720  illustrates the GUI  9200  after the user selects the color adjustment activation item  9246 . This causes the application to display four color adjustment sliders in the toolbar  9260 . As shown by help indicators  9705 , these sliders enable the user to adjust the saturation, sky colors, green colors, and skin tones of the displayed image. In addition, the color adjustment tools include a white balance item  9715 , indicated by the help indicator  9725 . 
     At the third stage  9730 , the user moves the blue skies slider  9745  to the right, in order to increase saturation in the sky colors of the image. This also causes the help indicator  9705  for the slider  9745  to move to the right. In doing so, the indicator begins to overlap with the help indicator for the greenery slider. As a result, the application automatically moves the greenery slider help indicator upwards (using a longer stem), so that the user can see the entire help indicator. 
     The fourth stage  9740  illustrates the result of the user selecting the white balance item  9715 . As shown, the application overlays a toolbar  9750  that provides numerous selectable white balancing options. With these items displayed, the application removes the help indicators  9705  for the color adjustment sliders, and instead overlays the indicators  9755  for the different white balance items. 
     VIII. Software Architecture 
     In some embodiments, the processes described above are implemented as software running on a particular machine, such as a computer or a handheld device, or stored in a machine-readable medium.  FIG. 98  conceptually illustrates the software architecture of an image viewing, editing, and organization application  9800  of some embodiments. In some embodiments, the image viewing, editing, and organization application is a stand-alone application or is integrated into another application, while in other embodiments the application might be implemented within an operating system. Furthermore, in some embodiments, the application is provided as part of a server-based solution. In some such embodiments, the application is provided via a thin client. That is, the application runs on a server while a user interacts with the application via a separate machine remote from the server. In other such embodiments, the application is provided via a thick client. That is, the application is distributed from the server to the client machine and runs on the client machine. 
     The image viewing, editing, and organization application  9800  includes a user interface (UI) interaction and generation module  9805 , a media ingest module  9810 , a histogram generator  9815 , editing modules  9820 , an image processor  9825 , an image display area generator  9830 , an image selector  9835 , an image tagger  9840 , an image comparator  9845 , and a sharing manager  9850 . The figure also illustrates stored data associated with the application  9800 : source images  9855 , image data  9860 , collections data  9865 , and cached images  9870 . 
     In some embodiments, the source images  9835  store image files (and, possibly, video files or other media) imported into the application (i.e., the local image database). In some embodiments, the image files may be associated with another image viewing and organization application with which the application  9800  communicates. The image data  9860  stores the image data structures of some embodiments, while the collection data  9865  stores the collection data (e.g., albums, events, journals, etc.). The cached images  9870  stores cached versions of the images (e.g., thumbnails, display size images, etc.). In some embodiments, the four sets of data  9855 - 9870  are stored in one physical storage (e.g., an internal hard drive, external hard drive, solid state memory, etc.). In some embodiments, the data may be split between multiple physical storages. 
       FIG. 98  also illustrates an operating system  9875  that includes input device driver(s)  9880 , display module  9885 , media import module  9890 , and network interface(s)  9895 . In some embodiments, as illustrated, the device drivers  9880 , display module  9885 , media import module  9890 , and network interface  9895  are part of the operating system even when the media editing application  9800  is an application separate from the operating system. 
     The input device drivers  9860  may include drivers for translating signals from a touchscreen, as well as a keyboard, mouse, touchpad, tablet, etc. A user interacts with one or more of these input devices, which send signals to their corresponding device driver. The device driver then translates the signals into user input data that is provided to the UI interaction and generation module  9805 . 
     The present application describes a graphical user interface that provides users with numerous ways to perform different sets of operations and functionalities. In some embodiments, these operations and functionalities are performed based on different commands that are received from users through different types of touchscreen devices. For example, the present application illustrates the use of touchscreen input (e.g., with one or more fingers) to control (e.g., select, move) objects in the graphical user interface. However, in some embodiments, objects in the graphical user interface can also be controlled or manipulated through other controls, such as a cursor. In some embodiments, cursor control is implemented through an input device that moves a cursor to different locations on the display of the device. Based on the location of the cursor, different input (e.g., mouse button clicks, etc.) can be used to perform different actions (e.g., selection of a GUI item). Thus, while many of the figures above do not illustrate a cursor, some embodiments perform the same actions with the use of a cursor (with or without touch control). 
     The display module  9885  translates the output of a user interface for a display device. That is, the display module  9885  receives signals (e.g., from the UI interaction and generation module  9805 ) describing what should be displayed and translates these signals into pixel information that is sent to the display device. The display device may be an LCD, plasma screen, CRT monitor, touchscreen, etc. In some touchscreen embodiments, the display module  9885  and the input device driver(s)  9880  are part of a single touchscreen driver. 
     The media import module  9890  receives media files (e.g., image files, etc.) from external storage devices (e.g., external drives, recording devices, etc.) through one or more ports (e.g., a USB port, Firewire port, etc.) of the device on which the media-editing application  9800  operates and translates this media data for the application  9800  or stores the data directly onto a storage of the device. 
     The UI interaction and generation module  9805  of the media editing application  9800  interprets the user input data received from the input device drivers and passes it to various modules, including the media ingest module  9810 , the editing modules  9820 , the image processor  9825 , the image display area generator  9830 , the image selector  9835 , and the image tagger  9840 . The UI interaction module also manages the display of the media-editing application GUI, and outputs this display information to the display module  9865 . This UI display information may be based on information from the editing modules  9815 , the timeline generator  9820 , the angle viewer generator  9827 , the playback module  9830 , the data  9835 - 9850 , etc. In addition, the module  9805  may generate portions of the UI based solely on user input—e.g., when a user moves an item in the UI that only affects the display rather than any of the other modules, such as moving a window from one side of the UI to the other or modifying the relative size of the clip browser and clip library. In some embodiments, the UI interaction and generation module  9805  generates a basic GUI and populates the GUI with information from the other modules and stored data. 
     The media ingest module  9810  manages the import of source media into the application  9800 . Some embodiments, as shown, receive source media from the media import module  9890  of the operating system  9875 . The media ingest module  9810  receives instructions through the UI module  9805  as to which files should be imported, then instructs the media import module  9890  to enable this import (e.g., from an external drive, an external camera, a camera of the device on which the application operates, a different application on the device, etc.). The media ingest module  9810  of some embodiments stores these images in the source images  9855 . In some embodiments, the media ingest module  9810  also manages the creation of image data structures upon import of source images. 
     The histogram generator  9815  generates color, texture, and shape histograms for each imported image in some embodiments. The histogram generator  9815  of some embodiments is described in detail above by reference to  FIG. 52 . 
     The editing modules  9815  include a variety of modules for editing images. The editing modules  9815  generate various editing GUI tools and translate input from these tools into edit instructions for an image (e.g., crop instructions, rotation instructions, color adjustment instructions, etc.). The image processor  9825  applies edit instructions to an image when the image needs to be output. For instance, when a user adds an edit to a displayed image, the appropriate one of the editing modules  9820  modifies the edit instructions for the image, and the image processor  9825  applies these instructions in order to generate the desired image. 
     The image display area generator  9830  handles the generation of the image display area. The image display area generator  9830  receives (e.g., from the UI interaction and generation module  9805  or the image selector  9835 ) a set of images to display. The generator  9830  of some embodiments calculates the average aspect ratio of the images, defines a grid in the image display area, calculates the number of pixels to use for displaying the images, and calculates the size for each image. 
     The image selector  9835  translates various user interactions into selections of one or more images to send to the image display area generator  9830 . When the user requests a set of similar images to a particular image, the image selector uses the image comparator  9845  to identify the similar images. The image comparator  9845  of some embodiments is described above by reference to  FIG. 52 . The image tagger  9840  receives user input to tag one or more images and modifies the data structures of the images accordingly. 
     The sharing manager  9850  manages the sharing of images on various photo sharing websites (e.g., Facebook®, Twitter®, Flickr®, etc.). In some embodiments, the sharing manager  9850  connects to these websites through the network interface(s)  9895  in order to upload images, receive and store the object ID for an uploaded image, and receive/upload comments on the image. 
     While many of the features of media-editing application  9800  have been described as being performed by one module (e.g., the UI interaction and generation module  9805 , the media ingest module  9810 , etc.), one of ordinary skill in the art will recognize that the functions described herein might be split up into multiple modules. Similarly, functions described as being performed by multiple different modules might be performed by a single module in some embodiments (e.g., the image display area generator  9830  and image selector  9835  might be part of the UI interaction and generation module  9805 ). 
     IX. Electronic Systems 
     Many of the above-described features and applications are implemented as software processes that are specified as a set of instructions recorded on a computer readable storage medium (also referred to as computer readable medium). When these instructions are executed by one or more computational or processing unit(s) (e.g., one or more processors, cores of processors, or other processing units), they cause the processing unit(s) to perform the actions indicated in the instructions. Examples of computer readable media include, but are not limited to, CD-ROMs, flash drives, random access memory (RAM) chips, hard drives, erasable programmable read-only memories (EPROMs), electrically erasable programmable read-only memories (EEPROMs), etc. The computer readable media does not include carrier waves and electronic signals passing wirelessly or over wired connections. 
     In this specification, the term “software” is meant to include firmware residing in read-only memory or applications stored in magnetic storage which can be read into memory for processing by a processor. Also, in some embodiments, multiple software inventions can be implemented as sub-parts of a larger program while remaining distinct software inventions. In some embodiments, multiple software inventions can also be implemented as separate programs. Finally, any combination of separate programs that together implement a software invention described here is within the scope of the invention. In some embodiments, the software programs, when installed to operate on one or more electronic systems, define one or more specific machine implementations that execute and perform the operations of the software programs. 
     A. Mobile Device 
     The image editing and viewing applications of some embodiments operate on mobile devices.  FIG. 99  is an example of an architecture  9900  of such a mobile computing device. Examples of mobile computing devices include smartphones, tablets, laptops, etc. As shown, the mobile computing device  9900  includes one or more processing units  9905 , a memory interface  9910  and a peripherals interface  9915 . 
     The peripherals interface  9915  is coupled to various sensors and subsystems, including a camera subsystem  9920 , a wireless communication subsystem(s)  9925 , an audio subsystem  9930 , an I/O subsystem  9935 , etc. The peripherals interface  9915  enables communication between the processing units  9905  and various peripherals. For example, an orientation sensor  9945  (e.g., a gyroscope) and an acceleration sensor  9950  (e.g., an accelerometer) is coupled to the peripherals interface  9915  to facilitate orientation and acceleration functions. 
     The camera subsystem  9920  is coupled to one or more optical sensors  9940  (e.g., a charged coupled device (CCD) optical sensor, a complementary metal-oxide-semiconductor (CMOS) optical sensor, etc.). The camera subsystem  9920  coupled with the optical sensors  9940  facilitates camera functions, such as image and/or video data capturing. The wireless communication subsystem  9925  serves to facilitate communication functions. In some embodiments, the wireless communication subsystem  9925  includes radio frequency receivers and transmitters, and optical receivers and transmitters (not shown in  FIG. 99 ). These receivers and transmitters of some embodiments are implemented to operate over one or more communication networks such as a GSM network, a Wi-Fi network, a Bluetooth network, etc. The audio subsystem  9930  is coupled to a speaker to output audio (e.g., to output different sound effects associated with different image operations). Additionally, the audio subsystem  9930  is coupled to a microphone to facilitate voice-enabled functions, such as voice recognition, digital recording, etc. 
     The I/O subsystem  9935  involves the transfer between input/output peripheral devices, such as a display, a touch screen, etc., and the data bus of the processing units  9905  through the peripherals interface  9915 . The I/O subsystem  9935  includes a touch-screen controller  9955  and other input controllers  9960  to facilitate the transfer between input/output peripheral devices and the data bus of the processing units  9905 . As shown, the touch-screen controller  9955  is coupled to a touch screen  9965 . The touch-screen controller  9955  detects contact and movement on the touch screen  9965  using any of multiple touch sensitivity technologies. The other input controllers  9960  are coupled to other input/control devices, such as one or more buttons. Some embodiments include a near-touch sensitive screen and a corresponding controller that can detect near-touch interactions instead of or in addition to touch interactions. 
     The memory interface  9910  is coupled to memory  9970 . In some embodiments, the memory  9970  includes volatile memory (e.g., high-speed random access memory), non-volatile memory (e.g., flash memory), a combination of volatile and non-volatile memory, and/or any other type of memory. As illustrated in  FIG. 99 , the memory  9970  stores an operating system (OS)  9972 . The OS  9972  includes instructions for handling basic system services and for performing hardware dependent tasks. 
     The memory  9970  also includes communication instructions  9974  to facilitate communicating with one or more additional devices; graphical user interface instructions  9976  to facilitate graphic user interface processing; image processing instructions  9978  to facilitate image-related processing and functions; input processing instructions  9980  to facilitate input-related (e.g., touch input) processes and functions; audio processing instructions  9982  to facilitate audio-related processes and functions; and camera instructions  9984  to facilitate camera-related processes and functions. The instructions described above are merely exemplary and the memory  9970  includes additional and/or other instructions in some embodiments. For instance, the memory for a smartphone may include phone instructions to facilitate phone-related processes and functions. The above-identified instructions need not be implemented as separate software programs or modules. Various functions of the mobile computing device can be implemented in hardware and/or in software, including in one or more signal processing and/or application specific integrated circuits. 
     While the components illustrated in  FIG. 99  are shown as separate components, one of ordinary skill in the art will recognize that two or more components may be integrated into one or more integrated circuits. In addition, two or more components may be coupled together by one or more communication buses or signal lines. Also, while many of the functions have been described as being performed by one component, one of ordinary skill in the art will realize that the functions described with respect to  FIG. 99  may be split into two or more integrated circuits. 
     B. Computer System 
       FIG. 100  conceptually illustrates another example of an electronic system  10000  with which some embodiments of the invention are implemented. The electronic system  10000  may be a computer (e.g., a desktop computer, personal computer, tablet computer, etc.), phone, PDA, or any other sort of electronic or computing device. Such an electronic system includes various types of computer readable media and interfaces for various other types of computer readable media. Electronic system  10000  includes a bus  10005 , processing unit(s)  10010 , a graphics processing unit (GPU)  10015 , a system memory  10020 , a network  10025 , a read-only memory  10030 , a permanent storage device  10035 , input devices  10040 , and output devices  10045 . 
     The bus  10005  collectively represents all system, peripheral, and chipset buses that communicatively connect the numerous internal devices of the electronic system  10000 . For instance, the bus  10005  communicatively connects the processing unit(s)  10010  with the read-only memory  10030 , the GPU  10015 , the system memory  10020 , and the permanent storage device  10035 . 
     From these various memory units, the processing unit(s)  10010  retrieves instructions to execute and data to process in order to execute the processes of the invention. The processing unit(s) may be a single processor or a multi-core processor in different embodiments. Some instructions are passed to and executed by the GPU  10015 . The GPU  10015  can offload various computations or complement the image processing provided by the processing unit(s)  10010 . In some embodiments, such functionality can be provided using CoreImage&#39;s kernel shading language. 
     The read-only-memory (ROM)  10030  stores static data and instructions that are needed by the processing unit(s)  10010  and other modules of the electronic system. The permanent storage device  10035 , on the other hand, is a read-and-write memory device. This device is a non-volatile memory unit that stores instructions and data even when the electronic system  10000  is off. Some embodiments of the invention use a mass-storage device (such as a magnetic or optical disk and its corresponding disk drive) as the permanent storage device  10035 . 
     Other embodiments use a removable storage device (such as a floppy disk, flash memory device, etc., and its corresponding drive) as the permanent storage device. Like the permanent storage device  10035 , the system memory  10020  is a read-and-write memory device. However, unlike storage device  10035 , the system memory  10020  is a volatile read-and-write memory, such as random access memory. The system memory  10020  stores some of the instructions and data that the processor needs at runtime. In some embodiments, the invention&#39;s processes are stored in the system memory  10020 , the permanent storage device  10035 , and/or the read-only memory  10030 . For example, the various memory units include instructions for processing multimedia clips in accordance with some embodiments. From these various memory units, the processing unit(s)  10010  retrieves instructions to execute and data to process in order to execute the processes of some embodiments. 
     The bus  10005  also connects to the input and output devices  10040  and  10045 . The input devices  10040  enable the user to communicate information and select commands to the electronic system. The input devices  10040  include alphanumeric keyboards and pointing devices (also called “cursor control devices”), cameras (e.g., webcams), microphones or similar devices for receiving voice commands, etc. The output devices  10045  display images generated by the electronic system or otherwise output data. The output devices  10045  include printers and display devices, such as cathode ray tubes (CRT) or liquid crystal displays (LCD), as well as speakers or similar audio output devices. Some embodiments include devices such as a touchscreen that function as both input and output devices. 
     Finally, as shown in  FIG. 100 , bus  10005  also couples electronic system  10000  to a network  10025  through a network adapter (not shown). In this manner, the computer can be a part of a network of computers (such as a local area network (“LAN”), a wide area network (“WAN”), or an Intranet, or a network of networks, such as the Internet. Any or all components of electronic system  10000  may be used in conjunction with the invention. 
     Some embodiments include electronic components, such as microprocessors, storage and memory that store computer program instructions in a machine-readable or computer-readable medium (alternatively referred to as computer-readable storage media, machine-readable media, or machine-readable storage media). Some examples of such computer-readable media include RAM, ROM, read-only compact discs (CD-ROM), recordable compact discs (CD-R), rewritable compact discs (CD-RW), read-only digital versatile discs (e.g., DVD-ROM, dual-layer DVD-ROM), a variety of recordable/rewritable DVDs (e.g., DVD-RAM, DVD-RW, DVD+RW, etc.), flash memory (e.g., SD cards, mini-SD cards, micro-SD cards, etc.), magnetic and/or solid state hard drives, read-only and recordable Blu-Ray® discs, ultra density optical discs, any other optical or magnetic media, and floppy disks. The computer-readable media may store a computer program that is executable by at least one processing unit and includes sets of instructions for performing various operations. Examples of computer programs or computer code include machine code, such as is produced by a compiler, and files including higher-level code that are executed by a computer, an electronic component, or a microprocessor using an interpreter. 
     While the above discussion primarily refers to microprocessor or multi-core processors that execute software, some embodiments are performed by one or more integrated circuits, such as application specific integrated circuits (ASICs) or field programmable gate arrays (FPGAs). In some embodiments, such integrated circuits execute instructions that are stored on the circuit itself. In addition, some embodiments execute software stored in programmable logic devices (PLDs), ROM, or RAM devices. 
     As used in this specification and any claims of this application, the terms “computer”, “server”, “processor”, and “memory” all refer to electronic or other technological devices. These terms exclude people or groups of people. For the purposes of the specification, the terms display or displaying means displaying on an electronic device. As used in this specification and any claims of this application, the terms “computer readable medium,” “computer readable media,” and “machine readable medium” are entirely restricted to tangible, physical objects that store information in a form that is readable by a computer. These terms exclude any wireless signals, wired download signals, and any other ephemeral signals. 
     While the invention has been described with reference to numerous specific details, one of ordinary skill in the art will recognize that the invention can be embodied in other specific forms without departing from the spirit of the invention. For instance, many of the figures illustrate various touch gestures (e.g., taps, double taps, swipe gestures, press and hold gestures, etc.). However, many of the illustrated operations could be performed via different touch gestures (e.g., a swipe instead of a tap, etc.) or by non-touch input (e.g., using a cursor controller, a keyboard, a touchpad/trackpad, a near-touch sensitive screen, etc.). In addition, a number of the figures (including  FIGS. 7, 34, 43, 47, 53, 59, 79, 86, and 89 ) conceptually illustrate processes. The specific operations of these processes may not be performed in the exact order shown and described. The specific operations may not be performed in one continuous series of operations, and different specific operations may be performed in different embodiments. Furthermore, the process could be implemented using several sub-processes, or as part of a larger macro process. Thus, one of ordinary skill in the art would understand that the invention is not to be limited by the foregoing illustrative details, but rather is to be defined by the appended claims.

Metadata:
Filing Date: 20120927
Publication Date: 20170307
Grant Date: 20170307
Priority Date: 20120306
Inventors: CUNNINGHAM CHRISTOPHER R.
Assignee: APPLE INC
CPC Classifications: [{"code": "G06F2203/04806", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06Q30/02", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06Q30/0251", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06Q30/0242", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04L67/02", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/04845", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/04842", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0485", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06T11/001", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/048", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F2203/04806", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/04883", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06Q50/01", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F9/451", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F16/54", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06Q30/02", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/0482", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/04842", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06Q30/0242", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06Q30/0251", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/04845", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/04883", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0485", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0485", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L51/066", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/04842", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F16/54", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F16/54", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/04817", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F2203/04806", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06Q50/01", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/04845", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/04883", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04N1/4074", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04N1/387", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0482", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F3/0482", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06Q50/01", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04L67/18", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/04842", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06Q30/02", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04L51/066", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06T11/001", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L12/5835", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F17/30274", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0482", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L67/26", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06K9/4642", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/04883", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06Q30/0242", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04L51/24", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/04845", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0485", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06K9/4652", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04N1/4074", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06Q30/0251", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F2203/04806", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04L67/02", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06F3/04817", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L67/55", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04L51/224", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L67/52", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 49115070