PATENT DOCUMENT

Publication Number: US-10332300-B2
Application Number: US-201715472214-A
Country: US
Kind Code: B2

Title: Depth of field for a camera in a media-editing application

Abstract:
Some embodiments provide a method that provides tools for defining a scene including media objects in a multi-dimensional space. The method provides a set of user interface tools for adjusting a region of focus for rendering the space from a particular location within a particular field of view. In some embodiments, the region of focus is a first region in the space within the particular field of view and the space further includes a second region outside of the region of focus within the particular field of view. In some embodiments, the method also provides a set of effects for applying to the second region but not the first region to visually indicate the first region as the region of focus within the space and the second region as a region outside of the region of focus within the space.

Claims:
We claim: 
     
       1. A method comprising:
 providing a display area for displaying at least one media object in a three-dimensional space; 
 providing a tool for defining a camera user interface tool for rendering the three-dimensional space from a particular location at a particular orientation; and 
 providing a set of user interface tools for adjusting a region of focus for rendering the space from the particular location within a particular field of view to adjust whether the at least one media object is rendered in focus, wherein the set of user interface tools comprise planes provided along a frustum of the camera user interface tool, wherein the planes are configured for dragging along the frustum to modify one or more depth of field parameters. 
 
     
     
       2. The method of  claim 1 , wherein the region of focus is a three-dimensional volume within the particular field of view in which the at least one media object is rendered in focus. 
     
     
       3. The method of  claim 2 , wherein the set of user interface tools comprise a tool for modifying a size of the region of focus. 
     
     
       4. The method of  claim 1 , wherein the set of user interface tools comprise handles provided along the frustum of the camera user interface tool. 
     
     
       5. The method of  claim 4 , wherein the handles are configured for dragging along the frustum to modify the one or more depth of field parameters. 
     
     
       6. The method of  claim 1 , further comprising:
 receiving a command to modify the one or more depth of field parameters of the camera user interface tool over a set duration; and 
 rendering a video from a perspective of a virtual camera in which the one or more depth of field parameters is modified in accordance with the command. 
 
     
     
       7. The method of  claim 6 , wherein receiving the command comprises receiving selection of a target object to render in focus at an end of the set duration. 
     
     
       8. The method of  claim 7 , wherein the camera user interface tool has an apparent focal plane, and wherein rendering the video comprises moving the apparent focal plane to a distance of the target object over the set duration. 
     
     
       9. The method of  claim 6 , wherein receiving the command comprises receiving a selection of a rate at which the one or more depth of field parameters is modified. 
     
     
       10. The method of  claim 6 , wherein receiving the command comprises receiving a request to expand a depth of field of the virtual camera. 
     
     
       11. The method of  claim 6 , wherein receiving the command comprises receiving a request to contract a depth of field of the virtual camera. 
     
     
       12. A non-transitory computer-readable medium including one or more sequences of instructions that, when executed by one or more processors, causes:
 providing a display area for displaying at least one media object in a three-dimensional space; 
 providing a tool for defining a camera user interface tool for rendering the three-dimensional space from a particular location at a particular orientation; and 
 providing a set of user interface tools for adjusting a region of focus for rendering the space from the particular location within a particular field of view to adjust whether the at least one media object is rendered in focus, wherein the set of user interface tools comprise planes provided along a frustum of the camera user interface tool, wherein the planes are configured for dragging along the frustum to modify one or more depth of field parameters. 
 
     
     
       13. The non-transitory computer-readable medium of  claim 12 , wherein the region of focus is a three-dimensional volume within the particular field of view in which the at least one media object is rendered in focus. 
     
     
       14. The non-transitory computer-readable medium of  claim 13 , wherein the set of user interface tools comprise a tool for modifying a size of the region of focus. 
     
     
       15. The non-transitory computer-readable medium of  claim 12 , wherein the set of user interface tools comprise handles provided along the frustum of the camera user interface tool. 
     
     
       16. The non-transitory computer-readable medium of  claim 15 , wherein the handles are configured for dragging along the frustum to modify the one or more depth of field parameters. 
     
     
       17. The non-transitory computer-readable medium of  claim 12 , further comprising one or more sequences of instructions that, when executed by the one or more processors, causes:
 receiving a command to modify the one or more depth of field parameters of the camera user interface tool over a set duration; and 
 rendering a video from a perspective of a virtual camera in which the one or more depth of field parameters is modified in accordance with the command. 
 
     
     
       18. The non-transitory computer-readable medium of  claim 17 , wherein receiving the command comprises receiving selection of a target object to render in focus at an end of the set duration. 
     
     
       19. The non-transitory computer-readable medium of  claim 18 , wherein the camera user interface tool has an apparent focal plane, and wherein rendering the video comprises moving the apparent focal plane to a distance of the target object over the set duration. 
     
     
       20. The non-transitory computer-readable medium of  claim 17 , wherein receiving the command comprises receiving a selection of a rate at which the one or more depth of field parameters is modified. 
     
     
       21. The non-transitory computer-readable medium of  claim 17 , wherein receiving the command comprises receiving a request to expand a depth of field of the virtual camera. 
     
     
       22. The non-transitory computer-readable medium of  claim 17 , wherein receiving the command comprises receiving a request to contract a depth of field of the virtual camera.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a division of U.S. application Ser. No. 12/245,698, filed Oct. 3, 2008, the content of which is incorporated herein by reference in its entirety. 
    
    
     FIELD OF THE INVENTION 
     The invention is directed towards image and video rendering. Specifically, the invention is directed towards depth of field properties for cameras in applications that render images and/or videos. 
     BACKGROUND OF THE INVENTION 
     Digital graphic design, video editing, and media editing applications provide designers and artists with tools to create much of the media seen today through various media outlets (television, movies, Internet content, etc.). These tools allow designers the ability to generate, compose, composite, and animate images and videos in a virtual three-dimensional space. 
     A computer simulating the three-dimensional space is able to produce (i.e., render) an image of the space as seen from a particular point in the space, looking in a particular direction, with a particular field of view. Some applications define a virtual camera at the particular point that is oriented in the particular direction and has properties that define the particular field of view. Such a virtual camera can be moved around the three-dimensional space, re-oriented, and may have various other properties that can be adjusted. The virtual camera is a user-interface tool that collectively represents the set of properties that define the direction, angle of view, and other attributes for rendering a scene from a particular point of view in a particular direction. 
     Virtual cameras have generally been defined as having a particular focal plane, a distance at which objects will appear in focus when the view from the camera is rendered. However, users may desire the ability to move the apparent focal plane of the virtual camera closer to or further from the camera in the context of a scene laid out in a three-dimensional space within an application. Users may also want to be able to render in focus a range of distances and expand or contract this range within the context of a scene. Accordingly, there is a need in the art for virtual cameras with highly modifiable focal properties. Furthermore, there is a need for user interface tools to enable easy modification of these focal properties. 
     SUMMARY OF THE INVENTION 
     Some embodiments of the invention provide novel user interface tools for rendering a particular region in a media-editing application from a particular location, in a particular direction, within a particular field of view. The media-editing application of some embodiments provides a set of tools for a user to define a three-dimensional space that includes two- and three-dimensional media objects (e.g., images, text, video clips, and other such objects). This application further provides a set of user interface tools for viewing and controlling the focal properties for rendering a particular region within the created space from a particular location, in a particular direction, within a particular field of view. 
     This application further provides a user interface tool, referred to in the discussion below as a virtual camera, to represent the location, direction, etc. from which the space is rendered. The virtual camera of some embodiments has a region of focus that is a two-dimensional region (e.g., a plane) or three-dimensional region (e.g., a volume) within the region rendered by the virtual camera. In these embodiments, objects located in the region of focus are rendered in focus by the virtual camera while special effects (e.g., blurring effects, coloring effects, etc.) are applied to objects outside the region of focus but within the region rendered by the virtual camera. 
     Some embodiments provide novel tools for viewing and controlling focal properties of the virtual camera, which can render a region from a particular location, in a particular direction, within a particular field of view. In some embodiments, the modifiable focal properties include the size of the region of focus, its distance from the camera, and the amount of effects applied to objects not within the region of focus. Some embodiments display the region of focus within the three-dimensional space of the media-editing application, enabling a user to modify the region of focus of a virtual camera within the context of a scene rendered by the virtual camera. 
     Specific modifiable parameters in some embodiments are an aperture, a focus offset, a near focus, and a far focus. The aperture parameter of some embodiments enables a user to affect the extent to which special effects (e.g., blurring) are applied to objects not in the region of focus. The focus offset parameter of some embodiments allows a user to move the region of focus closer to or further from the virtual camera. The near focus and far focus parameters of some embodiments allow a user to modify the size of the region of focus such that objects are in focus at more than one distance. Some embodiments also allow modification of other focal properties. 
     Various embodiments provide various user interface tools, or combinations of user interface tools, for adjusting the depth of field parameters. Sliders are one example of a user interface tool for modifying the aperture, focus offset, near focus, and far focus, as well as other parameters. Another type of user interface tool is one that provides for direct numerical input of the parameters (e.g., as a number of pixels, a percentage, etc.), either in conjunction with sliders or separately. Some embodiments provide moveable planes within the three-dimensional space of the media-editing application representing the focus offset, near focus, and far focus. 
     In some embodiments, the planes that represent the focus offset, near focus, and far focus move whenever a user modifies the parameters with a slider, direct numerical input, or other user interface tool. In some embodiments, a user can select and drag the planes directly in order to modify the depth of field parameters. The planes have handles that are used for dragging the planes in some embodiments. Some embodiments provide only one of the described controls for modifying the depth of field parameters, while other embodiments provide more than one of the described controls, or other controls that are not mentioned. 
     Some embodiments enable a user to set the depth of field properties of a virtual camera to change over a determined duration. A user can input (via any of the methods described above) a starting set of depth of field properties and a finishing set of depth of field properties, as well as a duration (e.g., length of time, number of frames of video, etc.) over which the parameters will change. When the scene is rendered from the point of view of the virtual camera, the depth of field properties change over the determined duration, from the starting properties to the finishing properties. 
     Some embodiments enable a user to select a target object to be brought into focus over the set duration. The user, in some embodiments, can select the target object, the duration, and the method of transition (e.g., constant movement of region of focus, accelerated movement of region of focus, etc.). When the scene is rendered, the region of focus will move from an initial distance from the camera to the distance of the target object from the camera, such that the target object is in focus at the end of the set duration. 
    
    
     
       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. 
         FIGS. 1-3  illustrate a simplified view of the modification of depth of field properties of a virtual camera of some embodiments. 
         FIG. 4  illustrates a three-dimensional compositing application of some embodiments. 
         FIG. 5  conceptually illustrates a process  500  of some embodiments for rendering an image from a virtual camera. 
         FIG. 6  illustrates a graph plotting the size of the circle of confusion against distance from a virtual camera of some embodiments. 
         FIGS. 7-14B  illustrate the modification of depth of field properties of a virtual camera via various user interface tools in a compositing application of some embodiments. 
         FIGS. 15-18  illustrate the use of handles along a camera frustum for modifying depth of field properties in some embodiments. 
         FIG. 19  conceptually illustrates a process of some embodiments for defining a change in depth of field parameters in order to bring a particular object into focus over a set duration. 
         FIGS. 20-22  illustrate the selection of a target object to be brought into focus in a compositing application of some embodiments. 
         FIG. 23  illustrates a perspective view of the first frame of a focus behavior of some embodiments. 
         FIG. 24  illustrates a view rendered from a virtual camera of the first frame of the focus behavior. 
         FIG. 25  illustrates a perspective view of the last frame of the focus behavior. 
         FIG. 26  illustrates a view rendered from the virtual camera of the last frame of the focus behavior. 
         FIG. 27  conceptually illustrates the software architecture of some embodiments of the compositing application. 
         FIG. 28  conceptually illustrates a computer system with which some embodiments of the invention are implemented. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In the following description, numerous details are set forth for purpose of explanation. However, one of ordinary skill in the art will realize that the invention may be practiced without the use of these specific details. 
     I. Overview 
     Some embodiments of the invention provide novel user interface tools for rendering a particular region in a media-editing (e.g., compositing) application from a particular location, in a particular direction, within a particular field of view. The media-editing application of some embodiments provides a set of tools for a user to define a three-dimensional space that includes two- and three-dimensional media objects (e.g., images, text, video clips, and other such objects). This application further provides a user interface tool, referred to in the discussion below as a virtual camera, to represent the location, direction, etc. from which the space is rendered. 
     This application further provides a user interface tool, referred to in the discussion below as a virtual camera, to represent the location, direction, etc. from which the space is rendered. The virtual camera of some embodiments has a region of focus that is a two-dimensional region (e.g., a plane) or three-dimensional region (e.g., a volume) within the region rendered by the virtual camera. In these embodiments, objects located in the region of focus are rendered in focus by the virtual camera while special effects (e.g., blurring effects, coloring effects, etc.) are applied to objects outside the region of focus but within the region rendered by the virtual camera. 
     Some embodiments provide novel tools for viewing and controlling focal properties of the virtual camera, which can render a region from a particular location, in a particular direction, within a particular field of view. In some embodiments, the modifiable focal properties include the size of the region of focus, its distance from the camera, and the amount of effects applied to objects not within the region of focus. Some embodiments display the region of focus within the three-dimensional space of the media-editing application, enabling a user to modify the region of focus of a virtual camera within the context of a scene rendered by the virtual camera. 
     Specific modifiable depth of field parameters in some embodiments are an aperture, a focus offset, a near focus, and a far focus. The aperture parameter of some embodiments enables a user to affect the extent to which special effects (e.g., blurring) are applied to objects not in the region of focus. The focus offset parameter of some embodiments allows a user to move the region of focus closer to or further from the virtual camera. The near focus and far focus parameters of some embodiments allow a user to modify the size of the region of focus such that objects are in focus at more than one distance. Some embodiments also allow modification of other depth of field parameters. 
     Some embodiments provide a display area that displays a virtual camera, the field of view of the virtual camera, and any objects to be rendered by the virtual camera. Some such embodiments provide planes in the field of view that represent the focus offset, near focus, and far focus parameters.  FIG. 1  illustrates a simplified view of a virtual camera  105  in a display area  100 . Lines  110  represent the field of view of the virtual camera. Within the field of view  110  are objects  111 ,  112 , and  113 . Dashed lines  115  illustrate a plane showing the focal plane of virtual camera  105 . When the scene shown in  FIG. 1  is rendered from the virtual camera  105 , object  112  will appear in focus, while blurring effects are applied to objects  111  and  113 . 
     Various embodiments provide various user interface tools, or combinations of user interface tools, for adjusting the depth of field parameters. Sliders are one example of a user interface tool for modifying the aperture, focus offset, near focus, and far focus, as well as other parameters. Another type of user interface tool is one that provides for direct numerical input of the parameters (e.g., as a number of pixels, a percentage, etc.), either in conjunction with sliders or separately. 
       FIG. 1  also illustrates the sliders  120 ,  125 ,  130 , and  135  of some embodiments used to modify depth of field parameters. In some embodiments,  120  is a slider for the focus offset,  125  is a slider for the near focus,  130  is a slider for the far focus, and  135  is a slider for the aperture. The focus offset can be positive or negative in some embodiments, and accordingly is set at zero when centered on the slider bar. In  FIG. 1 , the near focus and far focus parameters are set to zero, so the only plane that is in focus is at the focal plane  115 . The aperture is set at approximately the three-eighths mark, indicating that objects not in focus will be blurred a non-zero amount. In some embodiments, setting the aperture slider  135  to zero results in no blurring at all. 
     In some embodiments, the planes mentioned above that represent the focus offset, near focus, and far focus move whenever a user modifies the parameters with a slider, direct numerical input, or other user interface tool. In some embodiments, a user can select and drag the planes directly in order to modify the depth of field parameters. The planes have handles that are used for dragging the planes in some embodiments. Some embodiments provide only one of the described controls for modifying the depth of field parameters, while other embodiments provide more than one of the described controls, or other controls that are not mentioned. 
       FIG. 2  illustrates the scene from  FIG. 1  after a user has modified the focus offset with slider  120 . Slider  120  has been moved to the right, which moves the apparent focal plane represented by dashed lines  215 . When the scene shown in  FIG. 2  is rendered from the virtual camera  105 , object  113  will appear in focus, while blurring effects are applied to objects  111  and  112 . In some embodiments, object  111  will be blurred more than object  112  because it is further from the apparent focal plane  215 . 
       FIG. 3  illustrates the scene from  FIG. 1  after a user has modified the near focus and far focus parameters with sliders  125  and  130 , and the aperture parameter with slider  135 . Slider  125  has been moved a small amount, which moves the near focus plane  335  a short distance to the left (closer to the camera). Slider  130  has been moved a larger amount, which moves the far focus plane substantially to the right (further from the camera). Furthermore, slider  135  has been moved a substantial amount, resulting in an increase in the aperture. When the scene shown in  FIG. 3  is rendered from the virtual camera  105 , objects  112  and  113  will both appear to be in focus, while blurring effects are applied to object  111 . As a result of the increased aperture, object  111  will be rendered as blurrier than if the aperture had not been changed. 
     Some embodiments enable a user to set the depth of field properties of a virtual camera to change over a specific duration. A user can input (via any of the methods described above) a starting set of depth of field properties and a finishing set of depth of field properties, as well as a duration (e.g., length of time, number of frames of video, etc.) over which the parameters will change. When the scene is rendered from the point of view of the virtual camera, the depth of field properties change over the determined duration, from the starting properties to the finishing properties. For example, a user could set the parameters such that the focus offset would move from the distance shown in  FIG. 1  to the distance shown in  FIG. 2  over a set duration. 
     Some embodiments enable a user to select a target object to be brought into focus over the set duration. The user, in some embodiments, can select the target object, the duration, and the method of transition (e.g., constant movement of region of focus, accelerated movement of region of focus, etc.). When rendered, the region of focus will move from an initial distance from the camera to the distance of the target object from the camera, such that the target object is in focus at the end of the set duration. 
     II. Compositing Application 
       FIG. 4  illustrates a three-dimensional compositing application  400  provided by some embodiments. The compositing application  400  provides a primary display area  405 , an object selection area  410 , a first set of virtual camera controls  415 , a second set of virtual camera controls  420 , a preview display area  455 , a set of control icons  425 , and video rendering controls  430 . Some embodiments provide other features, such as multiple timelines indicating different camera behaviors. 
     The primary display area  405  includes objects  435 ,  440 , and  445 , as well as camera  450 . Each of the objects  435 ,  440 , and  445  are in the field of view of camera  450 . Each of the objects  435 - 445  has a corresponding entry in the object selection area  410 , as does the camera  450 . The primary display area  405  is displaying a perspective view of the scene in  FIG. 4 . In some embodiments, the primary display area can also display the view from camera  450  (or other cameras that have been defined). The primary display area  405  of some embodiments includes gridlines to assist a user in laying out a scene (e.g., to assist in determining the distance from an object to a virtual camera). 
     The first set of camera controls  415  provides controls for camera  450 . These controls allow a user to define the camera type and modify the angle of view for camera  450 , as well as controls to move and rotate the camera  450  within the scene shown in the display area  405 . The first set of camera controls also displays the focal length of the camera (i.e., the focal distance, the distance from the camera at which, without the modification of any depth of field parameters, the camera will render objects in focus. 
     The second set of camera controls  420  also provides controls for camera  450 . Some of the controls  420  provide the same abilities to a user as controls  415  (such as defining the camera type or modifying the angle of view). Furthermore, the second set of camera controls  420  allows a user to modify depth of field properties of the camera  450  with sliders and numerical input boxes  421 - 424 . Sliders  421 - 424  will be described in greater detail in Section III below. Some embodiments use different user interface items for controls  420  rather than slider tools or direct numerical input. 
     Above the second set of camera controls  420  is a preview display  455  of some embodiments. The preview display  455  displays the view through the camera  450 . As objects  435 - 445  are moved in the primary display area, or properties (e.g., depth of field parameters) of the camera  450  are changed, the appearance of the preview display  455  will change accordingly. 
     The set of control icons  425  includes numerous icons for performing various functions within the compositing application. The set of control icons  425  includes icon  426 , which allows a user to define a new camera (e.g., camera  450 ). Icon  427  allows a user to define a new behavior for an object, camera, or other item. In some embodiments, a behavior is a change in some property (e.g., position, orientation, etc.) of a camera or object over a period of time. Some embodiments allow a user to set behaviors of a camera relating to the camera&#39;s depth of field (e.g., bringing an object into focus). 
     III. Depth of Field Rendering 
     Some embodiments allow users to modify the depth of field parameters of virtual cameras in a compositing application. Doing so enables the user to adjust how objects in the field of view of a virtual camera appear when rendered (i.e., how in focus or blurred an object appears when rendered). How an object appears when rendered by a virtual camera is affected by the focal distance of the virtual camera and how objects that are not at the focal distance of the camera are blurred. 
       FIG. 5  illustrates a process  500  of some embodiments for rendering images (e.g., frames of video) from a virtual camera. The process  500  begins by determining (at  503 ) a first image to render. In some embodiments, the first image is the first frame of a scene. Sometimes the first image is a frame that a user has selected to render first (e.g., by dragging an indicator on a timeline to a particular point in the timeline indicating a particular frame). 
     After determining the image to render, the process  500  determines (at  505 ) the depth of field parameters for the virtual camera. In some embodiments, the depth of field parameters are specific to the particular image being rendered. For example, the parameters may change throughout a scene of a video that includes of a number of images, and the parameters must be determined for each particular image. In some embodiments, the image may be rendered as the user edits the depth of field parameters (or other properties, such as the location or orientation of the virtual camera rendering the image). The depth of field parameters of some embodiments include the region of focus (i.e., the distance or distances at which objects will be rendered as in focus), and how the focus falls off for objects not at such distances. Such parameters are input by users through a variety of user interface tools in some embodiments. 
     In some embodiments, the determination of the depth of field parameters includes calculating the circle of confusion at all distances from the camera. The circle of confusion is the size that a point appears as when rendered. The compositing application of some embodiments, when rendering an image, displays each point as a disk, the size of which is dependent on how blurred the point is to appear. Points that are further from the apparent focal plane (i.e., the distance from the camera at which objects are rendered in focus) of the virtual camera will have a larger circle of confusion.  FIG. 6  illustrates a graph  600 . The graph  600  plots the size of the circle of confusion on axis  610  against the distance from the virtual camera on axis  605 . Distances SN and SF represent the near and far ends of the range of distances in which objects will appear in focus. As objects at these distances are rendered as in focus, the circle of confusion (represented by dashed line  615 ) is zero from SN to SF. The dashed line illustrates the manner in which the circle of confusion increases at distances not within the distances from SN to SF. In some embodiments, a user can set parameters to affect the rate at which the circle of confusion grows as objects get further outside of the range in focus. 
     After determining the depth of field parameters, the process  500  determines (at  510 ) the blurring algorithm to be used. Some embodiments use an algorithm that applies a defocus filter to a disk the size of the circle of confusion. Some embodiments use algorithms that are less computationally intensive than a defocus disk, such as a Gaussian filter or other algorithms. In some embodiments, a user may select between different blurring algorithms for rendering an image. 
     The process  500  then selects (at  515 ) a pixel in the image to be rendered. Some embodiments start with a corner pixel, and traverse across an entire row of pixels before moving to a second row. Other embodiments start with a corner pixel, and traverse down an entire column before moving to a second column. Other embodiments use other algorithms for traversing through all the pixels in an image. 
     Once a pixel is selected, the process  500  determines (at  520 ) the distance of the pixel from the virtual camera. Each pixel effectively represents a ray emanating from the virtual camera at a particular angle (i.e., x degrees off of horizontal and y degrees off of vertical) or small range of angles. The distance at which the ray would first intersect an object is the distance of the pixel. The process  500  then calculates (at  525 ) the blurring around the pixel, based on the size of the circle of confusion at the pixel&#39;s distance and the blurring algorithm determined at  510 . 
     The process  500  then determines (at  530 ) whether there are more pixels for which the distance and blurring have not been calculated. If no more pixels remain, the process  500  proceeds to  535  to render the image. If more pixels remain, the process returns to  515  and repeats  515  through  530  until all pixels for the current image have been selected. 
     After rendering the image, the process  500  determines (at  540 ) whether to continue rendering. If the process determines to continue rendering, the process moves to  545  to determine the next image. For example, if a user is playing back a scene, then the next frame in the scene is the next image. After determining the next image to render, the process moves to  505  and repeats  505  through  535  to render the new image. 
     If the process  500  determines (at  540 ) that no more images are to be rendered, the process ends. For example, if the most recently rendered image is the last frame in a video, the process would not have any further images to render. Also, a user could select a user interface item (e.g., a stop button) that would cause the process to stop rendering images. 
     A. User Interface Tools for Modifying Depth of Field Parameters 
     In some embodiments, the depth of field parameters of a virtual camera can be modified by one or more sets of user interface tools. As discussed above, the depth of field parameters affect the extent to which objects in the field of view of the virtual camera will appear in focus when rendered by the virtual camera. 
       FIG. 7  illustrates a scene in a compositing application of some embodiments.  FIG. 7  illustrates a virtual camera  705 , and three objects  710 ,  715 , and  720 , at different distances from the virtual camera. The virtual camera  705  and the objects  710 - 720  are shown in a primary display area of the compositing application. The display area gives a perspective view of the scene and any virtual cameras that have been defined, such as camera  705 . 
       FIG. 8A  illustrates the selection, by a user, of virtual camera  705 . In some embodiments, a user selects a virtual camera by clicking on the virtual camera in the primary display area. In some embodiments, a user selects a virtual camera by clicking on the row for the camera in the object selection area  820 . A user can perform either of these methods, or other methods (e.g., shortcut keys) to select a virtual camera in some embodiments.  FIG. 8A  illustrates that row  815 , the row for camera  705 , is highlighted, because camera  705  is selected. 
     The selection of a virtual camera also causes the display of viewing frustum  805 . Viewing frustum  805  shows a user what is in the field of view of the virtual camera  705 . Plane  810  illustrates the focal plane of the camera  705  (i.e., the plane at which objects will be rendered in focus). The focal plane is the entire region of focus at this point. 
     Selection of the virtual camera  705  also causes the display of camera controls  825  in some embodiments. The camera controls of some embodiments include depth of field controls  830 .  FIG. 8B  illustrates an enlarged view of the depth of field controls  830  from  FIG. 8A . The illustrated depth of field controls include four sliders  831 ,  832 ,  833 , and  834 . Slider  831  controls the aperture of the virtual camera, which is used in some embodiments to determine how quickly the circle of confusion increases as objects are located further away from the focal plane (i.e., how blurry objects not in focus will be). 
     Slider  832  controls the focus offset. In some embodiments, the focus offset measures the distance from the focal plane of the camera (i.e., the distance at which objects are rendered in focus in the absence of modification of the depth of field properties of the camera) to the apparent focal plane. In other words, the focus offset allows the user to modify the apparent focal plane of the virtual camera without modifying any other properties of the camera. Slider  833  controls the near focus plane. Moving slider  833  to the right causes the near focus plane to move closer to the camera. The near focus plane, in some embodiments, represents the start of the region of focus (i.e., the distance closest to the camera at which objects will be rendered as completely in focus). Slider  834  controls the far focus plane. Moving slider  834  to the right causes the far focus plane to move further from the camera. The far focus plane, in some embodiments, represents the end of the region of focus (i.e., the distance furthest from the camera at which objects will be rendered completely in focus). 
     In some embodiments (e.g., the depicted embodiments), next to each of the sliders  831 - 834  is a numerical input tool. Moving a slider will affect the corresponding number in some embodiments. Furthermore, in some embodiments, the number can be changed directly, either by typing the desired number or by selecting the right and left arrows on either side of the number to increase or decrease the number. Directly changing the number will cause the corresponding slider to move accordingly in some embodiments. Also, directly changing the number will, if appropriate, cause the focal plane, near focus plane, or far focus plane to move in the display area. 
     The number associated with slider  831  is a measurement, in some embodiments, of the aperture of the virtual camera. This measurement is given in millimeters in some embodiments. The focus offset measurement, associated with slider  832 , is a distance in pixels from the focus offset in some embodiments. The focus offset is set to zero when the slider is centered (as in  FIGS. 8A and 8B ), and moving the offset to the left or right moves the apparent focal plane closer to or further from the camera, correspondingly. 
     For the near and far focus numerical measurements associated with sliders  833  and  834 , some embodiments use percentages of the foreground and background. Some embodiments define the foreground as the area in the field of view between the near plane of the camera frustum and the apparent focal plane. Similarly, some embodiments define the background as the area in the field of view between the apparent focal plane and the far plane of the camera frustum. Thus, if the near focus slider is set to 0%, none of the area in front of the focal plane will be rendered in focus. If the near focus slider is set to 100%, the entire foreground will be rendered in focus. Similarly, if the far focus slider is set to 100%, the entire background will be rendered in focus. 
     Some embodiments use only one slider to move both the near and far focus sliders. In some embodiments, this slider measures a percentage of the background/foreground. Other embodiments use a single slider that directly measures a distance (e.g., in units such as pixels) the near and far focus planes should move, such that the two planes are always equidistant from the apparent focal plane. Similarly, some embodiments use two sliders, as is shown in  FIGS. 8A and 8B , but measure distances (e.g., in pixels in relation to the apparent focal plane) rather than percentages. Some embodiments allow a user to choose which of the described sets of controls (or other control sets for controlling depth of field parameters) are provided by the compositing application. 
     In  FIG. 8A , cursor  840  is over the far focus slider.  FIG. 9A  illustrates the result of a user sliding the far focus slider to 47% with the cursor, as well as sliding the near focus slider to 57% (also using the cursor).  FIG. 9B  illustrates an enlarged view of the sliders from  FIG. 9A .  FIG. 9A  illustrates the appearance of near focus plane  933  and far focus plane  934 . The area between near focus plane  933  and far focus plane  934  (which includes objects  710  and  715 ) is the region of focus. Some embodiments display the objects as in or out of focus in the perspective view shown in the primary display area, whereas some embodiments save computational resources by only calculating the blurring of the objects upon rendering the scene from the virtual camera. 
       FIG. 10  illustrates a compositing application  1000  of some embodiments, with three objects  1010 ,  1015 , and  1020 , along with virtual camera  1025 , in the display area  1005 . The display area illustrates the objects from a different perspective than in  FIGS. 7-9A . The compositing application  1000  also includes a set of camera controls  1030 , including depth of field sliders  1031  (aperture),  1032  (focus offset),  1033  (near focus), and  1034  (far focus). 
       FIG. 11A  illustrates the scene from  FIG. 10  with the focus offset set to  239  (in units of pixels, though some embodiments use different units as mentioned above), the near focus set to 35% and the far focus set to 38% (in percentages, though some embodiments measure the near and far focus differently, as mentioned above).  FIG. 11B  illustrates an enlarged view of the sliders from  FIG. 11A . Focus offset plane  1132 , near focus plane  1133 , and far focus plane  1134  have also appeared as the corresponding parameter values are set to nonzero numbers. In  FIG. 11A , a cursor  1140  is over the right arrow on the numerical input for the focus offset slider. A user using a selection tool (e.g., a mouse button) with the cursor located over this arrow will increase the focus offset in some embodiments. Similarly, selecting the left arrow will decrease the focus offset. 
       FIG. 12A  illustrates the scene after the user has used the right arrow on the focus offset numerical input to increase the focus offset from 239 pixels to 627 pixels. Doing so has caused plane  1132  to move accordingly in the display area, and slider  1032  to move to the right. The user has also (via the slider, numerical input, or other method) increased both the near and far focus sliders.  FIG. 12B  illustrates an enlarged view of the sliders from  FIG. 12A . Whereas in  FIG. 11A , only object  1015  was within the range of focus, in  FIG. 12A  objects  1010 ,  1015 , and  1020  are all within the range of focus, and thus would all be rendered in focus. 
       FIG. 12A  also illustrates cursor  1140  over the edge of far focus plane  1134 . In some embodiments, a user can drag a plane directly in order to change the depth of field parameter associated with that plane. In some embodiments, the planes can only be dragged within a particular range. For example, the near focus plane  1133  in some embodiments cannot be moved so that it is further from the virtual camera than the focus offset plane  1132 . Similarly, the far focus plane  1134  in some embodiments cannot be moved so that it is closer to the virtual camera than the focus offset plane  1132 . 
     In some embodiments, the focus offset plane  1132  can only be moved so that it stays in between the near and far focus planes  1133  and  1134 . However, in other embodiments, the focus offset plane  1132  can be moved outside the range defined by the near and far focus planes  1133  and  1134 . When the focus offset plane is moved even with either the near or far focus plane, the near or far focus plane disappears and the focus offset plane can continue to move in that direction. In some such embodiments, in which the near and far focus are defined by percentages, moving the focus offset plane causes the numerical percentages and sliders for the near and far focus planes to change such that the near and far focus planes remain static. In other embodiments that define the near and far focus planes with percentages, moving the focus offset plane causes the near and far focus planes to move such that the numerical percentages and sliders for the near and far focus planes remain static. 
       FIG. 13A  illustrates that the far focus plane  1134  has been dragged by the user (using the cursor  1140 ) such that it is closer to the focus offset plane  1132  as compared with  FIG. 12A . Doing so has caused the far focus slider  1034  to move and the numerical value for the far focus to change from 51% to 11%.  FIG. 13B  illustrates an enlarged view of the sliders. The user has also moved the near focus plane such that object  1010  is no longer in the range that will be rendered as in focus. In the depicted embodiment, the user could have moved the near focus plane  1133  by moving the slider  1033 , by using the numerical input, or by dragging the near focus plane  1133  in the display area. 
       FIG. 13A  also illustrates cursor  1140  over near focus plane  1133 .  FIG. 14A  illustrates that the near focus plane  1133  has been moved by the user significantly closer to focal offset plane  1132 . This has created a small range of focus that only encompasses object  1015  and not much else. Moving the near focus plane  1133  also has caused the slider  1033  to move and the near focus numerical value to change from 44% to 14%.  FIG. 14B  illustrates an enlarged view of the sliders. 
     The compositing application of some embodiments, rather than displaying the focal offset, near focus, and far focus planes in the display area, displays handles along the camera frustum.  FIG. 15  illustrates a virtual camera  1505  with camera frustum  1510  and focal plane  1515 . Focal plane  1515  is the “physical” focal plane of the camera, representing the distance that would be in focus with no changes to the focus offset, near focus, or far focus parameters.  FIG. 15  also illustrates three sets of handles along the camera frustum. These handles are used in some embodiments to display and move the focus offset (handles  1520 ), near focus (handles  1525 ), and far focus (handles  1530 ) planes, thereby affecting the depth of field for the virtual camera. For the sake of clarity, only two handles from each of the three sets are labeled in  FIG. 15 . 
       FIG. 16  illustrates a cursor  1605  over one of the near focus handles  1525 . When a user selects the near focus handle  1525 , near focus plane  1625  appears. In some embodiments, the near focus plane  1625  only appears when one of the near focus handles  1525  is selected. The user can then drag the near focus plane  1625  either closer to or further from the virtual camera  1505 . Selecting one of the handles  1525  and dragging the plane  1625  causes all four handles  1525  to move in some embodiments. 
       FIG. 17  illustrates the cursor  1605  over one of the focus offset handles  1520 . When a user selects the focus offset handle  1520 , focus offset plane  1720  appears. In some embodiments, the focus offset plane  1720  only appears when one of the focus offset handles  1520  is selected. The user can then drag the focus offset plane  1720  either closer to or further from the virtual camera  1505 . Selecting one of the handles  1520  and dragging the plane  1720  causes all four handles  1520  to move in some embodiments. 
       FIG. 18  illustrates the cursor  1605  over one of the far focus handles  1530 . When a user selects the far focus handle  1530 , far focus plane  1830  appears. In some embodiments, the far focus plane  1830  only appears when one of the far focus handles  1530  is selected. The user can then drag the far focus plane either closer to or further from the virtual camera  1505 . Selecting one of the handles  1530  and dragging the plane  1830  causes all four handles  1530  to move in some embodiments. 
     Some embodiments incorporate the handles shown in  FIG. 15  into a compositing application such as that illustrated in  FIG. 8A , along with other controls to affect depth of field parameters such as sliders  831 - 834  and other inputs. In some such embodiments, the sliders and other inputs are affected by the movement of the handles in the same way as they are affected by movement of the depth of field planes, described above. 
     B. Rendering Changes in Depth of Field Parameters Over Time 
     Some embodiments enable a user to set the depth of field parameters of a virtual camera to change over a determined duration. A user can input a starting set of depth of field parameters and a finishing set of depth of field parameters, as well as a duration (e.g., length of time, number of frames of video, etc.) over which the parameters will change. In some embodiments, the user can input the starting and finishing sets of depth of field parameters with the user interface items (sliders, dragging planes or handles along the camera frustum, numerical input) described above. 
     When the scene portrayed by the virtual camera is rendered, the depth of field parameters change over the determined duration, from the starting parameters to the finishing parameters. For example, a user could set the parameters such that the focus offset and near and far focus would start as shown in  FIG. 8 , in which all three parameters are set to zero (only one plane is in focus, and it is at the physical focal plane of the camera), and end as shown in  FIG. 9  (in which the near and far focus planes are a substantial distance from the focal plane). When rendered as a video over the set duration, the video will start with all three objects blurry to some degree, and finish with objects  710  and  715  completely in focus and object  720  less blurry than at the start of the video. 
     Some embodiments enable a user to select a target object to be brought into focus over a set duration. The user, in some embodiments, can select the target object, the duration, and the method of transition (e.g., constant movement of focus offset, accelerated movement of focus offset, etc.). When rendered, the apparent focal distance of the camera (i.e., the distance at which objects are in focus) will move from an initial distance to the distance of the target object, such that the target object is in focus at the end of the set duration. 
       FIG. 19  conceptually illustrates a process  1900  of some embodiments for defining a change in depth of field parameters in order to bring a particular object into focus over a set duration. The process  1900  starts when input is received (at  1905 ) selecting a focus behavior for a particular virtual camera. 
       FIG. 20  illustrates a compositing application  2000 . A user has selected a focus behavior with a cursor  2005  to associate with virtual camera  2007 . In some embodiments, in order to select a focus behavior, a user selects the behavior icon  2010  (see also icon  427  of  FIG. 4 ). The behavior icon of some embodiments provides a drop-down menu (or other menu) with various types of behaviors that a user can select. For example, behavior icon  2010  includes basic motion behaviors, camera behaviors, as well as other behaviors. In some embodiments, camera behaviors enable a user to change parameters of a camera over a set duration (e.g., depth of field parameters, camera location and direction, etc.). In some embodiments, such as the embodiment depicted, a user can select a “focus” menu option that allows the user to choose an object to bring into focus over a set duration. 
     After receiving the selection of a focus behavior for a particular virtual camera, the process  1900  provides (at  1910 ) options for the focus behavior.  FIG. 20  illustrates that two sets of controls are provided, a moveable set of controls  2015  and a fixed set of controls  2020 . In the depicted embodiment, each of the two sets of controls  2015  and  2020  provides three user interface items with which a user can interact in order to define the camera focus behavior.  FIG. 20  illustrates a target user interface item  2021  that indicates a target object of the behavior (that is, the object upon which the camera will focus), a slider  2022  to set the transition time of the behavior (that is, to select when during the overall duration of the behavior the object will be brought into focus), and a drop-down menu  2023  with which a user can select the transition method (how the focal plane will move from its starting position to the target object). 
     Selecting a focus behavior also causes the provision of an object  2030  for the focus behavior in the object selection area  2025 . The focus behavior object  2030  is a sub-object of the camera with which it is associated. In some embodiments, after initially entering settings for the focus behavior, a user can select the focus behavior object  2030  in order to bring up the behavior controls  2015  and  2020  so that the settings can be adjusted. 
     At  1915 , the process  1900  receives a selection of a target object.  FIGS. 21 and 22  illustrate the selection of object  2105  as the target object for the selected focus camera behavior.  FIG. 21  illustrates a user dragging object  2105  with cursor  2005  into the target box  2110 . In some embodiments, the user clicks on the object from the object selection area  2030  and drags it into target box  2110  in order to select the object as the object upon which the camera will focus. In some embodiments, a user can select the object in the display view in order to move the object into the target box. Other embodiments use different methods of selecting an object (e.g., methods that do not use a target box as depicted in  FIG. 21 ). 
     In some embodiments, the target object may be either within the field of view of the camera or not within the field of view of the camera. If the object is not within the field of view of the camera, then in some embodiments, the behavior will move the focal plane to the distance of the target object. Some embodiments do not allow the target object to be out of the field of view of the camera. Other embodiments allow the target object to be out of the field of view, but rotate the camera during the behavior so that the object is within the field of view. 
       FIG. 22  illustrates the compositing application after the object  2105  has been successfully dragged into target box  2110 . A small version of the object  2105  is displayed in the target box  2110  (and in the target box in the moveable set of controls  2015 ), and the name of the object (“lift-off”, for object  2105 ) is displayed next to both target boxes. This indicates that at the end of the duration for the behavior, the apparent focal plane of the camera will be located at the depth of the selected object  2105 . 
     At  1920 , the process receives a duration for the behavior. Different embodiments provide different user interface tools for a user to set the duration. In some embodiments, a window pops up when a user selects a focus behavior, asking the user to input a duration for the behavior. In some embodiments, a user adjusts timeline  2035  located below the display area to set the duration for the behavior. In  FIG. 20 , timeline  2035  is set for  300  frames, the entirety of the scene. In some embodiments, a user can select the end of the timeline  2035  and drag it left or right to set the duration for the behavior. The starting point for the behavior can also be changed by dragging the left end of the timeline to the right, such that the behavior does not begin at the start of the scene. The scene length can be changed in some embodiments by altering the number of frames using user interface item  2040 . 
     At  1925 , the process receives a selection of transition options. In some embodiments, these are the transition time and transition method. In  FIG. 20 , either transition time slider  2022  can be used to set the percentage of the overall duration (set at  1920 ) during which the focal plane will actually be moving between its initial distance and the distance of the target object. In some embodiments, the transition time can also be input directly as a numerical percentage value, as shown in controls  2020 , or with other user interface tools. 
       FIG. 20  also illustrates drop-down menus  2023  labeled “speed”, each of which allows the selection of a transition method that defines how the focal plane moves from its initial position to the target object. In some embodiments, the different options include at least one of constant (the focal plane moves at a uniform speed), ease in (the focal plane starts slowly and works up to a uniform speed), ease out (the focal plane starts at a uniform speed and slows down as it approaches the target object, ease in and out (a combination of the two above), accelerate (the focal plane moves at an increasing velocity until reaching the target object), and decelerate (the focal plane moves at a decreasing velocity until reaching the target object). After  1925 , the process has received all the information to define the behavior, and therefore ends. 
     In the process  1900 , the process receives a selection of a target object, then a duration for the behavior, then the selection of transition options. In some embodiments, the order in which these are received is different. For instance, in some embodiments a user will input the duration before selecting a target object, or will input the transition options prior to either inputting the duration or selecting the target object. Furthermore, in some embodiments, the user can edit these options afterwards to redefine the behavior. For example, a user can modify the transition method if, after rendering the scene that includes the behavior, the user decides that the focal offset should move in a different way from the initial position to the target object. Some embodiments even allow a user to modify the transition options while rendering the scene. 
     In some embodiments, a user can render a scene including a focus behavior (e.g., by clicking on the play button  2045 ). Some embodiments render the entire scene, even if the behavior has a duration less than the length of the time. Some embodiments also enable a user to only render the scene for the duration of the behavior rather than for the length of the entire scene (e.g., with a play button specific to the behavior timeline  2035 ). 
       FIG. 23  illustrates a perspective view of the scene from  FIG. 20  at frame  1 , with the apparent focal plane at its initial position. In some embodiments, a user can select and drag time mark  2310  to move throughout the scene. In  FIG. 23 , time mark  2310  is at the start of the scene, frame  1 .  FIG. 24  illustrates the rendered view at frame  1  from the virtual camera  2007 . As can be seen in  FIG. 24 , objects  2105  (the target object) and  2415  are blurry, whereas object  2420  is in focus. 
       FIG. 25  illustrates a perspective view of the scene at frame  300  (the final frame in the scene). Time mark  2310  has been moved to the end of the timeline (either by the application playing the entire scene, or by a user dragging the mark to the end of the timeline). The focus offset plane is now at the distance of the target object, object  2105 , and the near focus and far focus planes have moved along with the focus offset plane. In some embodiments, the distances of the near and far focus planes from the focus offset plane stay constant. In other embodiments, the distances vary as the percentages (defined by the sliders as described above) stay constant.  FIG. 26  illustrates the rendered view at frame  300  from the virtual camera  2007 . As compared to the view at frame  1  ( FIG. 24 ), object  2415  is even blurrier, object  2105  has become blurry, and object  2420  is now in focus. 
     While the described embodiments uses a behavior to move the focus offset (apparent focal plane) to a target object, some embodiments allow for other behaviors to be specified. For example, in some embodiments, an object can be selected such that the object will be brought to the focal plane of a virtual camera over a set duration. Some embodiments allow a user to specify a behavior that moves the near or far focus plane such that a target object is brought into the region of focus. 
     IV. Software Architecture 
     In some embodiments, the compositing application described above is implemented as a set of modules.  FIG. 27  conceptually illustrates the software architecture of some embodiments of the compositing application. In some embodiments, the compositing 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.  FIG. 27  illustrates a cursor driver  2705 , a display module  2710 , a user interface (UI) interaction module  2715 , a depth of field calculation module  2720 , and a rendering engine  2725 . 
     In some embodiments, as illustrated, the cursor driver and/or display module are part of an operating system  2730  even when the compositing application is a stand-alone application separate from the operating system. The UI interaction module  2715  generates user interface items, such as the depth of field sliders and planes described above, and determines how they should be displayed within the compositing application. The UI interaction module  2715  passes this information to the display module  2710 , which enables the display of the compositing application, including the user interface items, on a computer monitor or other such display device (not shown). 
     A user interacts with the user interface items via input devices (not shown). The input devices, such as cursor controllers, send signals to the cursor controller driver  2705 , which translates those signals into user input data that is provided to the UI interaction module  2715 . The UI interaction module  2715  uses the user input data to modify the displayed user interface items. For example, if a user drags a cursor along a near focus slider, the UI interaction module  2715  will instruct the display module to move the slider on the display, and to move the near focus plane as well. The UI interaction module  2715  also passes data on user interactions affecting depth of field parameters to the depth of field (DOF) calculation module  2720 . 
     DOF calculation module  2720  calculates how in focus or blurry objects should appear when rendered. The DOF calculation module  2720  bases this information on the distances of the objects from a particular virtual camera, depth of field parameters (e.g., focal plane of the virtual camera, aperture, focus offset, near and far focus distances) for the virtual camera, the blurring algorithm selected, etc. In some embodiments, the DOF calculation module is one of a number of modules that apply special effects (i.e., any effect applied to a region in a space that modifies the appearance of the affected region, such as blurring or coloring effects) to a region within the field of view of the virtual camera. 
     The DOF calculation module  2720  passes the DOF calculations to the rendering engine  2725 . The rendering engine  2725  enables the output of audio and video from the compositing application. The rendering engine  2725 , based on information from the DOF calculation module  2720  and other modules (not shown), sends information about how to display each pixel of a scene to the display module  2710 . 
     While many of the features have been described as being performed by one module (e.g., the UI interaction module  2715  or DOF calculation module C 320 ), one of ordinary skill would recognize that the functions might be split up into multiple modules, and the performance of one feature might even require multiple modules. 
     V. Computer System 
     Computer programs for implementing some embodiments are executed on computer systems.  FIG. 28  illustrates a computer system with which some embodiments of the invention are implemented. Such a computer system includes various types of computer readable media and interfaces for various other types of computer readable media. Computer system  2800  includes a bus  2805 , a processor  2810 , a graphics processing unit (GPU)  2820 , a system memory  2825 , a read-only memory  2830 , a permanent storage device  2835 , input devices  2840 , and output devices  2845 . 
     The bus  2805  collectively represents all system, peripheral, and chipset buses that communicatively connect the numerous internal devices of the computer system  2800 . For instance, the bus  2805  communicatively connects the processor  2810  with the read-only memory  2830 , the GPU  2820 , the system memory  2825 , and the permanent storage device  2835 . 
     From these various memory units, the processor  2810  retrieves instructions to execute and data to process in order to execute the processes of the invention. Some instructions are passed to and executed by the GPU  2820 . The GPU  2820  can offload various computations or complement the image processing provided by the processor  2810 . In some embodiments, such functionality can be provided using CoreImage&#39;s kernel shading language. 
     The read-only-memory (ROM)  2830  stores static data and instructions that are needed by the processor  2810  and other modules of the computer system. The permanent storage device  2835 , 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 computer system  2800  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  2835 . 
     Other embodiments use a removable storage device (such as a floppy disk, flash drive, or ZIP® disk, and its corresponding disk drive) as the permanent storage device. Like the permanent storage device  2835 , the system memory  2825  is a read-and-write memory device. However, unlike storage device  2835 , the system memory is a volatile read-and-write memory, such a random access memory. The system memory 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  2825 , the permanent storage device  2835 , and/or the read-only memory  2830 . 
     The bus  2805  also connects to the input and output devices  2840  and  2845 . The input devices enable the user to communicate information and select commands to the computer system. The input devices  2840  include alphanumeric keyboards and pointing devices (also called “cursor control devices”). The output devices  2845  display images generated by the computer system. For instance, these devices display a GUI. The output devices include printers and display devices, such as cathode ray tubes (CRT) or liquid crystal displays (LCD). 
     Finally, as shown in  FIG. 28 , bus  2805  also couples computer  2800  to a network  2865  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. For example, the computer  2800  may be coupled to a web server (network  2865 ) so that a web browser executing on the computer  2800  can interact with the web server as a user interacts with a GUI that operates in the web browser. 
     Any or all components of computer system  2800  may be used in conjunction with the invention. For instance, in some embodiments the execution of the frames of the rendering is performed by the GPU  2820  instead of the CPU  2810 . Similarly, other image editing functions can be offloaded to the GPU  2820  where they are executed before the results are passed back into memory or the processor  2810 . However, a common limitation of the GPU  2820  is the number of instructions that the GPU  2820  is able to store and process at any given time. Therefore, some embodiments adapt instructions for implementing processes so that these processes fit onto the instruction buffer of the GPU  2820  for execution locally on the GPU  2820 . Additionally, some GPUs  2820  do not contain sufficient processing resources to execute the processes of some embodiments and therefore the CPU  2810  executes the instructions. One of ordinary skill in the art would appreciate that any other system configuration may also be used in conjunction with the present invention. 
     As mentioned above, the computer system  2800  may include any one or more of a variety of different computer-readable 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 (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, ZIP® disks, and floppy disks. 
     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 example, the application of blurring effects to regions outside a region of focus has been described in detail, but other special effects (i.e., any effect applied to a region in a space that modifies the appearance of the affected region, such as blurring or coloring effects). 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: 20170328
Publication Date: 20190625
Grant Date: 20190625
Priority Date: 20081003
Inventors: DEB, SIDHARTHA
ABBAS, GREGORY B.
NILES, GREGORY
SHEELER, STEPHEN
HUCKING, GUIDO
Assignee: APPLE INC
CPC Classifications: [{"code": "G06T15/00", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06T15/20", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06T19/20", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06T19/00", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06T15/00", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06T15/20", "inventive": false, "first": false, "tree": "[]"}, {"code": "G06T15/00", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06T19/00", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06T19/20", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 42075451