Patent Publication Number: US-2013250155-A1

Title: Method and device for focus selection in digital cameras

Description:
TECHNICAL FIELD 
     The present disclosure relates to digital cameras, and more particularly to a method and device for focus selection in digital cameras. 
     BACKGROUND 
     Digital cameras, including digital cameras built into smartphones and other multipurpose portable electronic devices, are typically provided an autofocus system to automatically focus an image captured by an image sensor of the digital camera. While somewhat effective and useful to novice users, automatic focus solutions provide limited or no user control over the focus of the digital camera. Accordingly, there remains a need for improved image capture methods and devices. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram illustrating a portable electronic device suitable for carrying out example embodiments of the present disclosure. 
         FIG. 2  is a block diagram illustrating an image capture assembly of the portable electronic device of  FIG. 1 . 
         FIG. 3  is a flowchart of a method for focus selection in a digital camera in accordance with one example embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made to the accompanying drawings which show example embodiments of the present disclosure. For simplicity and clarity of illustration, reference numerals may be repeated among the Figures to indicate corresponding or analogous elements. Numerous details are set forth to provide an understanding of the example embodiments described herein. The example embodiments may be practised without some of these details. In other instances, well-known methods, procedures, and components have not been described in detail to avoid obscuring the example embodiments described. The description is not to be considered as limited to the scope of the example embodiments described herein. 
     Any reference to direction or orientation stated herein is for convenience and is not intended to be limiting unless explicitly stated herein. Any directional references in relation to the graphical user interface (GUI) are relative to the screen orientation of the GUI rather than a fixed point or reference on the host electronic device. The term “user interface” is sometimes used herein to refer to the GUI for convenience. For the purpose of the present disclosure, the terms device orientation and device position are treated equivalently. 
     The present disclosure provides post-capture focus selection methods and devices. 
     In accordance with one example embodiment, there is provided a method for composing an image on a portable electronic device, the method comprising: focusing light received by an image sensor, the focusing including moving a lens between a number of focus positions; capturing an image using the image sensor at a plurality of the number of the focus positions, the captured images having different focus distances; storing the captured images; determining which of the captured images is an optimally focused image; and displaying the optimally focused image as a currently displayed image on a display of the portable electronic device. 
     In accordance with another example embodiment, there is provided a method for composing an image on a portable electronic device, the method comprising: focusing light received by an image sensor, the focusing including moving a lens between an initial focus position having a first focus distance and an adjusted focus position having a second focus distance; capturing an image using the image sensor at each of the initial focus position and an adjusted focus position; displaying one of the images captured at the initial focus position and the adjusted focus position which is determined to be an optimally focused image; and storing the image captured at the initial focus position and the image captured at the adjusted focus position in persistent memory. 
     In accordance with yet a further example embodiment, there is provided an electronic device, comprising: a processor; a lens coupled to a motor which is controlled by the processor; a display and an image sensor both coupled to the processor; wherein the processor is configured for performing the method(s) set forth herein. 
     In accordance with yet a further embodiment of the present disclosure, there is provided a computer program product comprising a computer readable medium having stored thereon computer program instructions for implementing a method on an electronic device, the computer executable instructions comprising instructions for performing the method(s) set forth herein. 
     Reference is first made to  FIG. 1  which illustrates a portable electronic device  100  (referred to hereinafter as merely electronic device  100  for convenience) in which example embodiments described in the present disclosure can be applied. The electronic device  100  described below has wireless communication capabilities; however, it is contemplated that the teachings of the present disclosure may be applied to devices without wireless communication capabilities. Examples of the electronic device  100  include, but are not limited to, a mobile phone, smartphone or superphone, tablet computer, notebook computer (also known as a laptop, netbook or ultrabook computer depending on the device capabilities), wireless organizer, personal digital assistant (PDA), electronic gaming device, and special purpose digital camera (which may be capable of both still image and video image capture). 
     The electronic device  100  includes a rigid case (not shown) housing the electronic components of the electronic device  100 . The electronic components of the electronic device  100  are mounted on a printed circuit board (not shown). The electronic device  100  includes a controller comprising at least one processor  102  (such as a microprocessor) which controls the overall operation of the electronic device  100 . Communication functions, including data and voice communications, are performed through a communication subsystem  104 . Data received by the electronic device  100  may be decompressed and decrypted by a decoder  106 . The communication subsystem  104  receives messages from and sends messages to a wireless network  101 . The wireless network  101  may be any suitable type of wireless network. 
     The processor  102  interacts with other components, such as one or more input devices  105 , Random Access Memory (RAM)  108 , Read Only Memory (ROM)  110 , a display  112  such as a colour liquid crystal display (LCD), persistent (non-volatile) memory  120  which may be flash erasable programmable read only memory (EPROM) memory (“flash memory”) or any other suitable form of memory, an image capture assembly  200 , a motion sensor  180  which enables to processor  102  to determine whether the electronic device  100  is in motion and the nature of any sensed motion at any appropriate time, e.g., when an image is captured, an orientation sensor  182  which enables the processor  102  to determine which direction the electronic device  100  is pointed at any appropriate time, e.g., when an image is captured, e.g., when an image is captured, global positioning system (GPS) device  184  which enables the processor  102  to determine GPS coordinates (i.e., location) of the electronic device  100  at any appropriate time, e.g., when an image is captured, auxiliary input/output (I/O) subsystems  150 , data port  152  such as serial data port (e.g., Universal Serial Bus (USB) data port), speaker  156 , microphone  158 , short-range communication subsystem  162 , and other device subsystems generally designated as  164 . The components of the electronic device  100  are coupled via a communications bus (not shown) which provides a communication path between the various components. 
     The display  112  typically includes a display area in which information may be displayed and a non-display area extending around the periphery of the display area. Information is not displayed in the non-display area. The non-display area may be utilized to accommodate, for example, electronic traces or electrical connections, adhesives or other sealants, and/or protective coatings around the edges of the display area. 
     The display  112  may be provided as part of a touch-sensitive display which provides an input device  105 . The display  112  which together with a touch-sensitive overlay (not shown) operably coupled to an electronic controller (not shown) comprise the touch-sensitive display. The touch-sensitive display is typically a capacitive touch-sensitive display which includes a capacitive touch-sensitive overlay may be any other suitable touch-sensitive display, such as a resistive, infrared, surface acoustic wave (SAW) touch-sensitive display, strain gauge, optical imaging, dispersive signal technology, acoustic pulse recognition, and so forth, as known in the art. The overlay of the touch-sensitive display may be an assembly of multiple layers in a stack which may include, for example, a substrate, a ground shield layer, a barrier layer, one or more capacitive touch sensor layers separated by a substrate or other barrier, and a cover. The capacitive touch sensor layers may be any suitable material, such as patterned indium tin oxide (ITO). 
     User-interaction with the GUI is performed through the input devices  105 . Information, such as text, characters, symbols, images, icons, and other items are rendered and displayed on the display  112  via the processor  102 . The processor  102  may interact with the orientation sensor to detect direction of gravitational forces or gravity-induced reaction forces so as to determine, for example, the orientation of the electronic device  100  in order to determine a screen orientation for the GUI. 
     The input devices  105  may include a keyboard, control buttons such as a power toggle (on/off) button (not shown), a camera button (not shown) for enabling a camera mode, a capture button (not shown) for enabling an image capture sequence when in the camera mode, one or more zoom buttons (not shown) for enabling a selection of a zoom setting when in the camera mode, and a navigation device (not shown) for navigating through stored data, such as digital images, menu choices and the like which are displayed on the display  112 . When the display  112  is provided as part of a touch-sensitive display, the capture button, zoom button and other camera controls may be provided by onscreen user interface elements displayed on the display  112  instead of, or in addition to, physical interface components. The keyboard may be provided instead of, or in addition to, a touch-sensitive display depending on the embodiment. At least some of the control buttons may be multi-purpose buttons rather than special purpose or dedicated buttons. 
     The electronic device  100  also includes a memory card interface  130  for receiving a removable memory card  132  comprising persistent memory, such as flash memory. A removable memory card  132  can be inserted in or coupled to the memory card interface  130  for storing and reading data by the processor  102  including, but not limited to still images and optionally video images captured the image capture assembly  200 . Other types of user data may also be stored on the removable memory card  132 . Other types of removable digital image storage media, such as magnetic hard drives, magnetic tape, or optical disks, may be used in addition to, or instead of, the removable memory card  132 . 
     The processor  102  operates under stored program control and executes software modules  175  stored in memory, for example, in the persistent memory  120 . As illustrated in  FIG. 1 , the software modules  175  comprise operating system software  177  and software applications  179 . The software applications  179  include a camera application  181  and photo viewer application  183 . The camera application  181  contains the logic for operating the image capture assembly  200  and capturing still images and optionally video images from the image capture assembly  200  and storing the still images and video images in the persistent memory  120 . The photo viewer application  183  contains logic for displaying data (i.e., still images and optionally video images) from the persistent memory  120  and data from the image capture assembly  200  on the display  112 . Persistent data  185 , such as user data, can also be stored in the persistent memory  120 . The persistent data  185  may include digital media files stored in the electronic device  100  such as still images and/or video images captured the image capture assembly  200 , or other still images and/or video images transferred, downloaded or otherwise stored on the persistent memory  120 . 
     The software modules  175  or parts thereof may be temporarily loaded into volatile memory such as the RAM  108 . The RAM  108  is used for storing runtime data variables and other types of data or information. Although specific functions are described for various types of memory, this is merely one example, and a different assignment of functions to types of memory could also be used. 
     Still images and optionally video images captured the image capture assembly  200  are stored in persistent memory after. The persistent memory may be one or any combination of the internal persistent memory  120 , the removable memory card  132  or remote persistent storage. The remote persistent storage may be a cloud based resource, such as a remote content server, accessible by the wireless network  101  or possibly via a wireline (e.g., via the data port  152 ) or short-range wireless connection (e.g., via the short-range communication subsystem  162 ) to a host computer having wireline access to the cloud based resource. The location at which captured still images and optionally video images is stored is typically a configurable setting which may be set by a user either in advance or at the time of capture. 
     The camera application  181  and/or photo viewer application  183  can access the remote persistent storage and optionally cloud based applications through the wireless network  101  or possibly via a wireline or short-range wireless connection to a host computer having wireline access to the cloud based resource. The use of cloud based or other remote persistent storage allows access to still images and optionally video images captured the image capture assembly  200  from nearly any computer or portable electronic device having access to the Internet. 
     The electronic device  100  also includes a battery  138  as a power source, which is typically one or more rechargeable batteries that may be charged, for example, through charging circuitry coupled to a battery interface such as the serial data port  152 . The battery  138  provides electrical power to at least some of the electrical circuitry in the electronic device  100 , and the battery interface  136  provides a mechanical and electrical connection for the battery  138 . The battery interface  136  is coupled to a regulator (not shown) which provides power V+ to the circuitry of the electronic device  100 . 
     A received signal, such as a text message, an e-mail message, or web page download, is processed by the communication subsystem  104  and input to the processor  102 . The processor  102  processes the received signal for output to the display  112  and/or to the auxiliary I/O subsystem  150 . A subscriber may generate data items, for example e-mail messages, which may be transmitted over the wireless network  101  through the communication subsystem  104 , for example. 
     The motion sensor  180  may comprise an accelerometer (such as a three-axis accelerometer) or other suitable motion sensor. The orientation sensor  182  may comprise an accelerometer (such as a three-axis accelerometer), electronic compass, gyroscope, or a combination thereof. Other suitable orientation sensors could be used instead of, or in addition to, the accelerometer, electronic compass and gyroscope. The motion sensor  180  and orientation sensor  182 , or parts thereof, may be combined or shared, for example, within an integrated component. The processor  102 , or controller (not shown) of a three-axis accelerometer, can convert acceleration measurements into device orientations. 
     The electronic device  100  may connect to a host personal computer (not shown) via the serial data port  152  or short-range communication subsystem  162  communicating over a suitable interconnection, such as a USB connection, Firewire™ connection, Bluetooth™ connection or the like. 
     Referring now to  FIG. 2 , the image capture assembly  200  of the electronic device  100  will be described in more detail. The image capture assembly  200  includes an image processor  202  which performs various image processing functions described below. The image processor  202  is typically a programmable image processor but could be, for example, a hard-wired custom integrated circuit (IC) processor, a general purpose microprocessor, or a combination of hard-wired custom IC and programmable processors. When the image capture assembly  200  is part of a multipurpose portable electronic device such as a mobile phone, smartphone or superphone, at least some of the functions of the image capture assembly  200  may be performed by the main processor  102  of the host electronic device  100 . It is contemplated that all of the functions performed by the image processor  202  could be performed by the main processor  102 , in which case the image processor  202  can be omitted. Furthermore, the image capture assembly  200  has access to various components of the host electronic device  100 , and can receive inputs from and send outputs to various components of the host electronic device  100 , input such as the input devices  105 , motion sensor  180 , orientation sensor  182 , GPS  184 , RAM  108 , persistent memory  120  and the like. 
     The image capture assembly  200  also includes a zoom lens  204  including a mechanical assembly of lens elements which is connected to and controlled by a focus adjuster  206 , such as zoom and focus motors (e.g., servo motors), which adjust the focal length and focus distance of the zoom lens  204 . 
     The focus adjuster  206  is coupled to the image processor  202  which sends zoom and focus signals to the focus adjuster  206  during zoom and focus operations. The zoom lens  204  has a variable aperture the size of which is expressed by an f-number (sometimes called focal ratio, f-ratio, f-stop, or relative aperture) which is a measure of the diameter of the aperture of the zoom lens  204 . The f-number is the focal length divided by the “effective” aperture diameter. The f-number is a dimensionless number that is a quantitative measure of lens “speed”. 
     The zoom lens  204  provides an image to an image sensor  208 . The image sensor  208  may have a number of aspect ratios, such as a 4:3 and 16:9 image aspect ratios, and a number of image resolutions. In some embodiments, the image sensor  208  is a charge-coupled device (CCD) sensor; however, a complementary metal-oxide semiconductor (CMOS) sensor or other suitable image sensor could be used. An adjustable aperture and shutter assembly (not shown) in the zoom lens  204  is used to control the aperture size and the exposure time of the image sensor  208 . In other embodiments, the zoom lens  204  could be replaced with a fixed focal length lens (also known as a “prime” lens) in which case the focus adjuster  206  merely adjusts the focus distance of the lens. Digital zoom may be provided by digital image processing performed by the image processor  202  of the image capture assembly  200  or processor  102  (rather than optical zoom provided by the zoom lens  204 ). In other embodiments, the shutter assembly could be omitted in favour of an electronic shutter. 
     The image processor  202  controls the image sensor  208  by supplying various control signals to the image sensor  208 . The image processor  202  also controls the focus adjuster  206 , an exposure detector  222  which determines the amount of available light, and a flash  224  for emitting light to illuminate a scene being captured by the focus lens  204 . The input devices  105  provide user controls which can control the operation of the image capture assembly  200 . The image processor  202  can use the input from the exposure detector  222  to determine the exposure time required to capture an image based on the amount of available light and other settings. The image processor  202  can activate the flash  224  to increase the amount of available light, for example, in response to the input from the exposure detector  222 . 
     An analog captured image signal A output from the image sensor  208  is amplified and converted to a digital captured image signal by an analog signal processor (ASP)  210 . The ASP  210  includes an analog-to-digital (A/D) converter among other functional components. A digital captured image signal B output by the ASP  210  is temporarily stored in a buffer memory  212 , such as a Dynamic random-access memory (DRAM) buffer memory. 
     The image processor  202  produces focus signals which drive the focus adjuster  206  (e.g., zoom and focus motors) to adjust the focus of an image captured by the image sensor  208  and output as the captured image signal. The image processor  202  produces focus signals in response to the activation of the capture button. A digital captured image signal C output by the ASP  210  is provided to the image processor  202  which performs autofocus calculations on the digital captured image signal C. Focus signals are sent to the focus adapter  206  to adjust the focus distance of the zoom lens  204  as necessary as a result of the output the autofocus calculations. The autofocus calculations are typically performed using either contrast detection or phase detection methods which rely on moving the zoom lens  204  to make minor adjustments in the focus distance until a maximal (or optimal) contrast is obtained. The autofocus calculations assume that maximal (or optimal) contrast corresponds to maximal sharpness. The nature of the autofocus calculations is outside the scope of the present disclosure and will not be described in further detail herein. Autofocus methods and calculations suitable for use by the image processor  202  are well known in the art and will be readily known to the skilled person. 
     The digital captured image signal C may also be output to the display  112  to provide a preview image. The digital captured image signal C may be used to provide a real-time or “live” preview in which a real-time image (or an approximation of an image) of the image captured with the image sensor  208  is displayed on the display  112  as a thumbnail image (e.g., reduced size/resolution version) of the captured image for graphical processing efficiency, or alternatively a dedicated electronic viewfinder device. 
     A digital captured image signal D provided by the buffer memory  212  is subsequently processed by the image processor  202  to produce a processed digital image file, which may contain a still digital image or a video image. 
     The image processor  202  may perform various other image processing functions, including colour interpolation and colour and tone correction to produce rendered image data, such as standard Red Green Blue (sRGB) image data. The rendered image data is then stored in the memory of the removeable memory card  132  or persistent memory  120 . In some embodiments, the rendered image data may be compressed before storing, for example, the rendered image data may be JPEG compressed and stored as a JPEG image file, which may be in the 
     Exchangeable image file (Exif) format or other suitable format which preferably supports image metadata, such as one or more of a date/time the image was captured, f-number of the zoom lens  204  at which the image was captured, GPS location and pointing direction when the image was captured and possibly other camera settings. 
     The processing performed by the image processor  202  is typically controlled by firmware stored in a firmware memory (not shown), which may be flash memory or any other suitable form of memory. The image processor  202  processes the digital input image from the buffer memory  212 , using RAM memory (such as RAM  108  of the host electronic device or possibly separate, dedicated RAM) to store intermediate results during processing. 
     While the components of the electronic device  100  are shown as separate blocks in  FIGS. 1 and 2 , the functions of various components may be combined in actual processing elements, circuits and the like. Furthermore, some of the functional blocks of  FIGS. 1 and 2  may be separated into one or more sub blocks when implemented in actual processing elements, circuits and the like. 
       FIG. 3  is a flowchart of a method  300  for focus selection in accordance with one example embodiment of the present disclosure. The method  300  may be carried out, at least in part, by firmware or software such as the camera application  181 , executed by the processor  102  and/or image processor  202 . Coding of software for carrying out such a method  300  is within the scope of a person of ordinary skill in the art provided the present disclosure. The method  300  may contain additional or fewer processes than shown and/or described, and may be performed in a different order. Computer-readable code executable by at least one processor  102  and/or image processor  202  to perform the method  300  may be stored in a computer-readable medium such as the persistent memory  120 . 
     At  302 , the image capture assembly  200  is activated, for example, by engaging a camera mode of the electronic device  100 . The camera mode can be activated by a camera button or a corresponding menu option displayed on the display  112 . The zoom lens  204  is set to a default position which is typically a wide angle position. 
     At  304 , the image sensor  208  captures images which are output to the display  112  to provide an image preview mode which enables the user to compose the images to be captured based on a real-time preview image. The digital captured image signal C provides captured images for preview on the display  112 . As part of the composing, the user may activate zoom buttons to set a desired field of view. Alternatively, a dedicated electronic viewfinder device may be provided for the display of the real-time preview image. 
     At  306 , the electronic device  100  monitors for and detects when the capture button is activated. 
     At  308 , when the electronic device  100  detects that the capture button is activated, focusing of the captured image is performed. The digital captured image signal C provides captured images for the image processor  202  to perform autofocus calculations as well as providing captured images for preview on the display  112 , as mentioned previously. 
     As part of the focusing, the image processor  202  stores an initial captured image in the buffer memory  212  ( 308 A). The initial captured image is an image captured by the image sensor  208  when the electronic device  100  detects that the capture button is activated. The image processor  202  then analyses the digital captured image signal C using autofocus calculations (e.g., contrast maximization) ( 308 B) and produces focus signals based on the analysis (e.g., the result of the autofocus calculations) which drive the focus adjuster  206  to move the zoom lens  204  to adjust the focus of the image ( 308 C). The focus is adjusted by moving the zoom lens  204  from an initial position to an adjusted position to adjust the focus distance of the zoom lens  204 . The image processor  202  stores the newly captured image in the buffer memory  212  ( 308 A) and analyses the new digital captured image signal C. The newly captured image is an image captured by the image sensor  208  when the zoom lens  204  is in the adjusted position ( 308 B). The image processor  202  produces additional focus signals which drive the focus adjuster  206  to move the zoom lens  204  to further adjust the focus of the image when the maximal contrast (or other optimal contrast) or other threshold has not been reached ( 308 C). The process of storing a captured image in the buffer memory  212 , analysing the captured image and adjusting the position of the zoom lens  204  ( 308 A- 308 C) is iteratively repeated until the maximal contrast (or other optimal contrast) or other threshold is reached. The process is performed during one autofocus cycle. 
     During the focusing, the autofocus images at each lens position are stored in the buffer memory  212  at  308 A. Typically, a sequence of autofocus images is stored in a chronological order in the buffer memory  212 . The images are typically stored in association with a date and/or time at which the images were captured to assist subsequent retrieval and/or processing, e.g. for accessing and retrieval of images based on the chronological order of the time at which the images were captured. The focusing typically takes approximately 1 second or less to complete. The number of autofocus images stored during this time depends on the speed of the autofocus system, which is typically dependent on the image sensor  208 , focus adjuster  206 , image processor  202  and buffer memory  212 . The number of autofocus images is expected to be between 2 and 20, more typically between 5 and 15 but may vary depending on the particular hardware and imaging settings which are used. 
     Each of the stored autofocus images has a different focus distance in accordance with the position of the zoom lens  204  when the image was captured. For example, in one autofocus image a foreground of a scene may be in focus (i.e., sharp) while a background of the scene is not in focus (i.e., blurry), in another autofocus image the background of the scene may be in focus while the foreground of the scene is not in focus, and in yet another autofocus image a subject (e.g., person or object of interest) of the scene may be in focus while the background and foreground of the scene are not in focus. 
     When the focusing is complete, the autofocus images may be stored in a common, composite file rather than as individual autofocus image files. The composite file may include metadata about each of the autofocus images, such as one or more of a date/time the image was captured, f-number of the zoom lens  204  at which the image was captured, GPS location and pointing direction when the image was captured and possibly other camera settings. The composite file may be a common file format or a proprietary file format. The individual autofocus image files, or the composite file, may be stored in persistent memory such as the memory  120  or the removeable memory card  132  when the focusing is complete. When the focusing is in progress, the autofocus images are stored typically in the buffer memory  212  as mentioned previously. 
     At  310 , when focusing is complete, an optimally focused image is displayed on the display  112  of the electronic device as a post-capture preview image. Typically, the post-capture preview image is displayed as a thumbnail image (e.g., reduced size/resolution version) of the optimally focused image for graphical processing efficiency. 
     At  312 , a new autofocus image is selected in response to input. The autofocus image is selected either from individual autofocus image files or the composite file, depending on the embodiment. As mentioned previously, the autofocus images may be stored in the buffer memory  212  or persistent memory, depending on the embodiment. The electronic device  100  may display a post-capture focus selection user interface which facilities input from the user to select and display alternative autofocus images. The post-capture focus selection user interface CaO be activated by a corresponding button or menu option displayed on the display  112 . A previous or next autofocus image in the sequence of autofocus images may be selected as the new autofocus image in accordance with corresponding input. The previous or next autofocus image in the sequence of autofocus images is the closest image in sequence (e.g., closest in the chronological order) either before or after the currently displayed autofocus image. In one example embodiment, a left input (such as a left swipe on a touch-sensitive display or activation of a left navigational button—which may be a physical button or an onscreen button displayed on a touch-sensitive display) may select a previous autofocus image in the sequence whereas a right input may select a next autofocus image in the sequence (such as a right swipe on a touch-sensitive display or activation of a right navigational button—which may be a physical button or an onscreen button displayed on a touch-sensitive display). 
     As mentioned previously, each of the stored autofocus images captured by the method  300  has a different focus distance. Accordingly, the method  300  allows a user to a select a focus of a scene after the image has been captured. Conventionally, when an image is captured the focus distance is fixed so that only a part of the image within a depth of the field of the zoom lens  204  is in focus (i.e., sharp) while other parts of the image outside the depth of field are not in focus (i.e., blurry). The parts of the image which are in focus and the parts of the image which are not in focus are fixed and cannot be changed. While some digital cameras provide so-called continuous capture or burst modes, these modes are merely a series of autofocused images taken in rapid succession. Accordingly, each image captured in the series of autofocused images is the optimally focused image which results from the completion of a normal autofocus cycle. Thus, while these modes allow rapid image capture, these modes lack the ability to select or choose a focus of the captured images. Thus, users cannot select a desired focus distance and are instead limited to the optimal focus distance determined by the autofocus system (e.g., image processor  202 ). Accordingly, an aspect of the present disclosure is the recognition that existing autofocus methods restrict a user&#39;s ability to set the focus distance which sometimes results in the selecting of a focus distance which is different from a desired focus distance. The present disclosure describes a post-capture focusing selection method which seeks to address this and optionally other shortcomings. 
     The method  300  presents a solution which allows the focus distance to be selected post-capture by modifying the passive autofocus method to store images taken during focus searching rather than discarding the autofocus images after the optimal focus distance is determined by the autofocus system and the optimally focused image is created. The present solution does not require any additional hardware and requires little or no changes to existing hardware found in conventional digital cameras. 
     If desired, the autofocus method used by the image processor  202  could be configured to use an increased interval of focus positions of the zoom lens  204  compared with conventional autofocus methods. For example, the interval of movement of the zoom lens  204  during autofocus searching may be increased to provide a large number of autofocus images, each with a smaller change in focus distance. This is expected to result in smaller changes in the focus distance between the autofocus images captured during autofocus searching, thereby permitting more subtle control over the focus distance. It is conceivable that the range of the focus positions for a given zoom lens  204  (or prime lens) may be increased to increase the range of the focus distances in the autofocus images capture during autofocus searching. 
     The steps and/or operations in the flowcharts and drawings described herein are for purposes of example only. There may be many variations to these steps and/or operations without departing from the teachings of the present disclosure. For instance, the steps may be performed in a differing order, or steps may be added, deleted, or modified. 
     While the present disclosure is described, at least in part, in terms of methods, a person of ordinary skill in the art will understand that the present disclosure is also directed to the various components for performing at least some of the aspects and features of the described methods, be it by way of hardware components, software or any combination of the two, or in any other manner. Moreover, the present disclosure is also directed to a pre-recorded storage device or other similar computer readable medium including program instructions stored thereon for performing the methods described herein. 
     The present disclosure may be embodied in other specific forms without departing from the subject matter of the claims. The described example embodiments are to be considered in all respects as being only illustrative and not restrictive. The present disclosure intends to cover and embrace all suitable changes in technology. The scope of the present disclosure is, therefore, described by the appended claims rather than by the foregoing description.