Patent Publication Number: US-2005134722-A1

Title: System and method for indicating exposure information during image capture

Description:
TECHNICAL FIELD  
      The present invention is generally related to image capture devices and, more particularly, is related to a system and method for displaying exposure information during image capture.  
     BACKGROUND  
      Images captured using extended exposure times are referred to as time-exposure images. Time-exposure images may be difficult to capture since the amount of image exposure time must be controlled to capture an image having desirable exposure qualities. For example, photographing objects of interest at night requires a relatively long exposure time in the absence of illumination provided by supplemental illumination sources, such as a flash or strobe. In other situations, such as capturing images of celestial objects, the use of supplemental illumination sources may not be desirable, and therefore require long exposure times. Furthermore, if the object of interest is not stationary, such as a moving animal, or if the object of interest is changing over time, such as a reproducing single cell organism, insufficient time may be available for the capture of the necessary plurality of time-exposure images.  
      To capture a time-exposure image, the user of the image capture device typically determines an initial amount of exposure time of the object of interest using an exposure meter (external or internal to the camera) or an exposure reference guide. Often, a plurality of different images of the same object are captured, each with a different exposure time. The user can later view the captured images and then select desirable images. Such a technique is time consuming since a plurality of time-exposure images must be captured. Also, capturing the plurality of time-exposure images may unnecessarily utilize limited image capture device resources, such as the digital memory used by a digital image capture device.  
      Another category of time-exposure images are those where there is object movement that creates an intentional blur in the image, such as fireworks or lightning streaking through the sky, or a ballerina dancing across a stage. Not only can correct exposure be difficult to judge, but also determining image content of the resulting image (determining how the image will look like while the action is being exposed) can be challenging. Many times, capturing an image having desirable image content becomes a trial and error process. Thus, a plurality of images are usually captured and later evaluated after the images are processed.  
     SUMMARY  
      The user assistance system provides a system and method for assisting a user in operation of an image capture device. Briefly described, one embodiment is a method comprising non-destructively reading a plurality of photosensitive sites residing in a photosensor on a periodic basis, generating exposure information for each one of the non-destructive reads, and displaying the exposure information after the exposure information is generated, such that the exposure information is displayed on the periodic basis.  
      Another embodiment comprises a photosensor; a plurality of photosensitive sites residing in the photosensor; a processor configured to cause a plurality of non-destructive readings of the photosensitive sites on a periodic basis, and configured to determine the exposure information for each of the plurality of readings; and a display configured to display each of the determined exposure information on the periodic basis. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The components in the drawings are not necessarily to scale relative to each other. Like reference numerals designate corresponding parts throughout the several views.  
       FIG. 1  is a block diagram illustrating an embodiment of a real-time exposure information system implemented in an image capture device.  
      FIGS.  2 A-C are illustrative diagrams of the real-time exposure information comprising an exposure histogram and a developing thumbnail image displayed on the display of the image capture device of  FIG. 1 .  
      FIGS.  3 A-C illustrative diagrams of another embodiment of the real-time exposure information comprising a developing thumbnail image or a developing full-sized image displayed on the display of the image capture device of  FIG. 1 .  
      FIGS.  4 A-C are illustrative diagrams of another embodiment of the real-time exposure information comprising an exposure histogram displayed on the display of the image capture device of  FIG. 1 .  
      FIGS.  5 A-C are illustrative diagrams of another embodiment of the real-time exposure information comprising a developing image and an exposure histogram displayed on the display of the image capture device of  FIG. 1 .  
      FIGS.  6 A-C are illustrative diagrams of another embodiment of the real-time exposure information comprising a preview image and an exposure histogram displayed on the display of the image capture device of  FIG. 1 .  
       FIG. 7  is a flowchart illustrating an embodiment of a process for displaying exposure information during image capture. 
    
    
     DETAILED DESCRIPTION  
       FIG. 1  is a block diagram illustrating an embodiment of a real-time exposure information system  100  implemented in an image capture device  102 . As a time-exposure image is captured, real-time exposure information is displayed to the user such that the user understands exposure and/or image content of the captured image on a real-time basis. Accordingly, the user can conclude image capture based upon the viewed real-time exposure information, thereby capturing a time-exposure image having desirable exposure characteristics.  
       FIG. 1  includes selected external and internal components of the image capture device  102 , demarked by cut-away lines  104   a  and  104   b.  Internal components, illustrated between cut-away lines  104   a  and  104   b,  include at least memory element  106 , photosensor  108  and processor  110 . In one embodiment, memory element  106  includes a captured image data region  112  for storing captured images and the real-time exposure information logic  114 . In another embodiment, the captured image data region  112  resides in a suitable detachable memory device (not shown).  
      Image capture device  102  includes as external components an optional control button  116 , a lens unit  118 , an image capture actuation button  120 , an optional viewfinder  122 , a power switch  124  and a display  126 . The display  126  displays real-time exposure information to the user during image capture. Display  126  is any suitable device used for previewing the target scene image prior to capturing, for viewing real-time exposure information, for viewing a menu or the like, and/or for viewing captured images. For convenience of illustration, display  126  is illustrated on the top of image capture device  102 .  
      Operation of the image capture device  102  is initiated by actuation of the power switch  124  or an equivalent device having the same functionality. Display  126  may display a view of an image currently visible through the viewfinder  122  and/or detected by photosensor  108 , referred to herein as a preview image.  
      Photosensor  108  comprises a matrix of light detecting photosensitive sites  128 . As each of the photosensitive sites  128  are exposed to light passing through the lens unit  118 , the photosensitive sites  128  collect charge or the like in proportion to the amount of light detected during the image capture exposure period. Accordingly, at the conclusion of image capture exposure period, light information from the photosensitive sites  128  can be determined such that the determined light information corresponds to the amount of light detected by each photosensitive site  128  during the image capture exposure period. This process of obtaining light information from photosensitive sites  128  is referred to hereinafter as “reading” the photosensitive sites  128 .  
      Embodiments of the real-time exposure information system  100  are configured to collect light information (read) from all or selected ones of the photosensitive sites  128  periodically during the image capture exposure period. When the light information from a photosensitive site  128  is read, the light information is read from the photosensitive site  128  without corrupting, losing, destroying or otherwise interfering with the accumulation of charge or the like by the photosensitive site  128 . Accordingly, the photosensitive site  128  is “non-destructively read” since the amount of detected light (collected charge or the like) by the photosensor site  128  is not corrupted, lost, destroyed or otherwise interfered with. That is, light information can be periodically and repeatedly read from the photosensitive site  128  in a non-destructive manner (hereinafter referred to as a “non-destructive read”) while the photo sensitive sites continue to collect charge or the like. The terms “periodic” or “periodically,” as used herein, may refer to equal time periods, unequal time periods, or varying time periods.  
      Prior to capturing an image, the user of the image capture device  102  may visually preview the image on display  126  or view the object to be captured through viewfinder  122 . Photosensor  108  is disposed in a suitable location behind lens unit  118  such that an image of object to be captured may be focused onto photosensor  108  for capturing. When the user has focused the image and is satisfied with the focused image and image framing, the user actuates the image capture actuation button  120  (also referred to as a shutter button or a shutter release button) to cause image capture device  102  to begin image capture of the object, referred to herein as the beginning of the image capture exposure period.  
      At the conclusion of the image capture exposure period, light is prevented from passing through lens unit  118  so that the photosensitive sites  128  cease detecting light (cease accumulating charge or the like). Then, light information corresponding to the total amount of light detected by the photosensitive sites  128  during the image capture exposure period is communicated to processor  110 . Processor  110 , executing various image processing routines known in the art, then processes and saves data corresponding to the captured image into the captured image data region  112  (or in another suitable data storage medium).  
      In situations where the amount of light detected by the photosensitive sites  128  is large, such as during a sunny day, or when a supplemental light sources such as a flash is used during image capture, the image capture exposure period is very short. However, in other situations where the amount of light detected by the photosensitive sites  128  is relatively small, the image capture exposure period may be relatively long so that the photosensitive sites  128  detect a sufficient amount of light such that a captured image having desirable characteristics can be generated. Such situations result in the capture of a “time-exposure” image.  
      For example, the time required for the photosensitive sites  128  to detect a meaningful amount of light when images are captured during low ambient light conditions, such as at night without the use of a supplemental light source, may be relatively great. One such exemplary situation is capturing images of celestial objects, such as the moon, planets and/or stars. Accordingly, the real-time exposure information system  100  periodically provides the user of the image capture device  102  information corresponding to the amount of accumulated light detected by the photosensitive sites  128  during the relatively long image capture exposure period required to capture an image at night.  
      As another example, a time-exposure image may be desirable in relatively high ambient light conditions, such as an action shot where a blurred effect caused by object motion is desirable. One such exemplary situation is capturing an image of a dancer wherein portions of the dancer&#39;s body appear as painted brush strokes or the like in the final captured image.  
      As yet another example, a time-exposure image may be desirable in situations where a process is being recorded. If the process occurs only one time, such as capturing an image of a dividing living cell, it is desirable to capture an image of the process with desirable exposure quality the first time. Otherwise, the process must be repeated. If the cell of interest divides only once, it is desirable to capture an image of the dividing cell on the first attempt.  
      It is appreciated that the above-described situations of capturing a time-exposure image are merely illustrative of some of the situations where the user of the image capture device uses a relatively long image capture exposure period. Accordingly, embodiments of the real-time exposure information system  100  periodically and repeatedly provides exposure information to the user so that the user understands the amount of exposure of the image being captured.  
      In situations where a relatively short image capture exposure period is used for image capture, the real-time exposure information system  100  may be deactivated. In those situations where a relatively long image capture exposure period is used for capturing a time-exposure image, the real-time exposure information system  100  would be selectively activated. The activation of the real-time exposure information system  100  in one embodiment is controlled by the controller  116 , implemented as a suitable switch, button or the like. Controller  116  may also be a multi-purpose device. In another embodiment, the real-time exposure information system  100  is controlled via a suitable graphical menu interface (GUI) selection system, or the like, that is displayed on display  126 .  
      When the real-time exposure information system  100  is operating, all of, or selected ones of, the photosensitive sites  128  are periodically read and the current reading of the light information is communicated to processor  110 . Information corresponding to the current reading of detected light information is generated (or determined) by processor  110 , and then displayed on display  126 . This displayed information, in its various forms, is referred to as “exposure information” herein. Furthermore, the exposure information is displayed immediately after the exposure information is generated (or as soon as possible, depending upon the processing speed or capability of the image capture device  102 ). In one embodiment, the exposure information corresponds to light level information that is presented in a readily understood format, such as, but not limited to, a histogram. Exposure information may also include displaying an “exposure image” that indicates image content to the user. An exposure image corresponds to the developing image of the object based upon the current reading of the photosensitive sites  208  during the image capture process.  
      The exposure information is displayed periodically with sufficiently short intervals between non-destructive readings such that the user can understand the progression of image exposure during the image capture exposure period. In video image capture and video display devices, it is known that the capturing and subsequent display of the video frames at a frequency of approximately twenty to thirty times per second will be perceived by a viewer as a live video. Accordingly, some embodiments of the real-time exposure information system  100  perform reads of photosensitive sites  128 , and then display of the corresponding exposure information, at rates that approximate the display rate of video devices. It is appreciated that the frequency of the non-destructive reading of the photosensitive sites  128 , and the display of the corresponding exposure information, may be done at any suitable frequency so long as the user perceives in a meaningful manner the on-going exposure of the image during the image capture exposure period. That is, the user is able to understand the current exposure of the object that is being captured on a “real-time” basis.  
      In some embodiments, the non-destructive reads of photosensitive sites  128 , and the display of the corresponding exposure information, may be performed at rates that are less than the display rate of video devices. For example, the frequency may be at five displays per second in one embodiment. Even though the frequency is less than that used by video devices, the user perceives in a meaningful manner (i.e., real-time) the on-going exposure of the image during the image capture exposure period.  
      As described above, some embodiments of the real-time exposure information system  100  perform reads of all of the photosensitive sites  128  on a periodic basis. These embodiments provide a relatively great amount of exposure information to the user, and may allow a high-resolution captured image to be displayed to the user. That is, the user views progression of the exposure of the entire captured image (up to the resolution provided by the display  126 ).  
      In other embodiments, selected ones of the photosensitive sites  128  are non-destructively read on a periodic basis. These embodiments provide a relatively lesser amount of exposure information to the user. However, the user is able to meaningfully view progression of the exposure of the captured image. For example, one embodiment reads selected ones of the photosensitive sites  128  and displays a low-resolution image as the exposure information. Another embodiment non-destructively reads selected ones of the photosensitive sites  128  such that a thumbnail image (a reduced size image) is displayed to the user as the exposure information.  
      In other embodiments, all or selected ones of the photosensitive sites  128  are non-destructively read on a periodic basis and an exposure histogram is determined. The exposure histogram is displayed to the viewer as the exposure information.  
      An exposure histogram is generated by plotting how many times a particular exposure level (or range) occurs for the photosensitive, sites  128  that are periodically read. Different exposure values (or ranges) are plotted along the horizontal axis in increasing order. An exposure value corresponds to a value of the light information received from each non-destructive readings of the photosensor sites  128 . Position of individual points on the exposure histogram (for plotted exposure values or ranges) are determined by summing the corresponding occurrences of a particular value (or range) of light information read from the photosensitive sites  128 . Thus, the vertical axis corresponds to the number of pixels having the same exposure value (or within the same range of exposure values). Accordingly, as image exposure increases, the histogram is “stretched” to the right.  
      For convenience, the exposure histograms illustrated in the several FIGS. are shown as a single-line graph. However, it is appreciated any suitable display of the exposure information in a graphical format are the intended exposure histograms used by the various embodiments of the real-time exposure information system  100 . For example, the exposure histogram may employ a plurality of bars or vertically oriented lines or the like.  
      The user understands progression of the exposure of the captured image by viewing the displayed exposure information. Embodiments may display the exposure information by displaying a histogram or the like (thereby indicating light level information) and/or displaying the developing exposure images (thereby indicating image content). Accordingly, embodiments of the exposure information system  100  enable the user to conclude (terminate) image capture at a time selected by the user. That is, the user selectively ends the image capture exposure period when the user is satisfied with the exposure and image content of the image being captured.  
      In one embodiment, the user initiates image capture (starts the image capture exposure period) by actuating the image capture actuation button  120  (also referred to as a shutter button or a shutter release button). For example, in one embodiment the user presses downward on the image capture actuation button  120 . When the user is satisfied with the exposure of the captured image, the user then releases the image capture actuation button  120 , thereby selectively ending image capture (ending the image capture exposure period).  
      In another embodiment, the user similarly initiates image capture by actuating the image capture actuation button  120 , and then releases the image capture actuation button  120 . When the user is satisfied with the exposure of the captured image, the user then actuates the image capture actuation button  120  a second time, thereby selectively ending image capture.  
      In yet another embodiment, a remote image capture actuation button (not shown) that is communicatively coupled to the image capture device  102  is actuated in one of the above-described manners. Such a remote image capture actuation button may be communicatively coupled to the image capture device  120  using any suitable means, such as, but not limited to, a wire connection, an infrared medium, a radio frequency (RF) media, a sonic based media, a microwave media, or the like.  
      It is appreciated that any suitable means for initiating image capture (starting the image capture exposure period) and terminating image capture (ending the image capture exposure period) may be employed by embodiments of the real-time exposure information system  100 .  
      As described above, embodiments of the real-time exposure information system  100  perform reads of photosensitive sites  128 , and displays the corresponding exposure information, at rates such that the user is able to understand the current exposure of the object that is being captured. That is, the user views displayed exposure information on a “real-time” basis. Exemplary embodiments of exposure information are described below.  
      FIGS.  2 A-C are illustrative diagrams of the real-time exposure information comprising an exposure histogram  204  and an exposure image  206  displayed on the display  126  (  FIG. 1 ). In this exemplary embodiment, the developing exposure image  206  is referred to as a developing thumbnail image for convenience. The developing thumbnail image is a reduced-size, lower-resolution image that indicates image content to the user.  
       FIG. 2A  is a view  202  displaying an exposure histogram  204  and a developing thumbnail image  206  on display  126  such that the user viewing the view  202  understands that the photosensitive sites  128  ( FIG. 1 ) have received relatively little exposure based upon that particular non-destructive reading. The exposure histogram  204  comprises a graph  208  indicating the exposure of the photosensitive sites  128 . Graph  208  indicates that the photosensitive sites  128  have detected a relatively small amount of light since the graph  208  is closer to the left-hand side of the exposure histogram  204 . The developing thumbnail image  206  shows the current image of the object of interest, ajar  210  having a design  212  thereon. Developing thumbnail image  206  indicates to the user that the photosensitive sites  128  have detected a relatively small amount of light since the jar  210  is barely discernable in the thumbnail image  206 .  
       FIG. 2B  is a view  214  displaying another exposure histogram  204  and another developing thumbnail image  206  on display  126 , based upon a non-destructive reading of the photosensitive sites  128  taken at a later time than the non-destructive reading used to generate view  202 . Accordingly, the user viewing the view  214  understands that the photosensitive sites  128  ( FIG. 1 ) have received relatively more exposure. Graph  208  indicates that the photosensitive sites  128  have detected relatively more light since the graph  208  has extended further to the right of the exposure histogram  204 . Developing thumbnail image  206  now indicates that the photosensitive sites  128  have detected relatively more light since the jar  210  is more discernable in the thumbnail image  206 . Details  216  of the jar  210  are now becoming visible.  
       FIG. 2C  is a view  218  displaying another exposure histogram  204  and another developing thumbnail image  206  on display  126  based upon a non-destructive reading of the photosensitive sites  128  taken at a later time than the non-destructive reading used to generate view  214 . Accordingly, the user viewing the view  218  understands that the photosensitive sites  128  ( FIG. 1 ) have received even more exposure. Graph  208  indicates that the photosensitive sites  128  have detected relatively more light since the graph  208  has extended almost fully to the right-hand side of the exposure histogram  204 . Developing thumbnail image  206  now indicates that the photosensitive sites  128  have detected relatively more light since the jar  210 , design  212  and details  216  are clearly discernable in the developing thumbnail image  206 .  
      In this simplified example illustrating three of a series of displayed exposure information (exposure histograms  204  to illustrate light level information and developing thumbnail images  206  to illustrate image content), it is assumed that the user is satisfied with the exposure shown in view  218 , and that the user then selectively ends image capture (ends the image capture exposure period). It is understood that only three of a plurality of time-sequenced exposure information displays are illustrated in  FIGS. 2A-2C  (and also with FIGS.  3 A-C,  4 A-C,  5 A-C and  6 A-C described below), and that the user would be viewing in real time a sequential plurality of periodic exposure information as exposure of the captured image progresses.  
      FIGS.  3 A-C are illustrative diagrams of another embodiment of the real-time exposure information comprising a developing exposure image. The exposure image may be displayed as a developing thumbnail image or a developing full-sized image on the display  126  ( FIG. 1 ). In one embodiment, the developing thumbnail image or a low-resolution image may be displayed on a portion of the display  126 , convenient when only selected photosensitive sites  128  are read. In another embodiment, a developing full-sized, higher-resolution image is displayed on display  126 .  
       FIG. 3A  is a view  302  displaying a developing exposure image  304  of the object of interest, a jar  210  having a design  212  thereon. View  302  indicates that the photosensitive sites  128  have detected a relatively small amount of light since the jar  210  is barely discemable in the view  302 .  FIG. 3B  is a view  306  based upon another non-destructive reading of the photosensitive sites  128  taken at a later time than the non-destructive reading used to generate view  302 . Accordingly, the user viewing view  306  understands that the photosensitive sites  128  ( FIG. 1 ) have detected relatively more light since the developing exposure image  304  of the jar  210  and details  216  are more discernable in the view  306 .  FIG. 3C  is a view  308  based upon another non-destructive reading of the photosensitive sites  128  taken at a later time that the non-destructive reading used to generate view  304 . Accordingly, the user viewing the view  308  understands that the photosensitive sites  128  ( FIG. 1 ) have detected relatively more light since developing exposure image  304  of the jar  210  and details  216  are clearly discernable in the view  306 .  
      FIGS.  4 A-C are illustrative diagrams of another embodiment of the real-time exposure information comprising an exposure histogram displayed on the display  126  ( FIG. 1 ).  FIG. 4A  is a view  402  displaying an exposure histogram. In this embodiment, a developing thumbnail image, a low-resolution developing exposure image or a high-resolution developing exposure image, is not displayed. View  402  indicates that the photosensitive sites  128  have detected a relatively small amount of light since the graph  208  is closer to the left-hand side of the exposure histogram  204  in the view  402 .  FIG. 4B  is another view  404  based upon a non-destructive reading of the photosensitive sites  128  taken at a later time than the non-destructive reading used to generate view  402 . Accordingly, the user viewing view  404  understands that the photosensitive sites  128  ( FIG. 1 ) have detected relatively more light since the graph  208  has extended further to the right of the exposure histogram  204  in the view  404 .  FIG. 4C  is yet another view  406  based upon a non-destructive reading of the photosensitive sites  128  taken at a later time that the non-destructive reading used to generate view  404 . Accordingly, the user viewing the view  406  understands that the photosensitive sites  128  ( FIG. 1 ) have detected relatively more light since the graph  208  has extended almost fully to the right-hand side of the exposure histogram  204  in the view  406 .  
      FIGS.  5 A-C are illustrative diagrams of another embodiment of the real-time exposure information comprising a developing full-sized image and an exposure histogram displayed on the display  126  ( FIG. 1 ). Here, the exposure histogram  204  is displayed over, superimposed on, or overlaid on the full-sized developing exposure image of the jar  210 . Accordingly, the user viewing the view  502  ( FIG. 5A ) understands that the photosensitive sites  128  have received relatively little exposure since the graph  208  is closer to the left-hand side of the exposure histogram  204  and since the developing exposure image of the jar  210  is barely discernable. The user viewing the view  504  ( FIG. 5B ) understands that the photosensitive sites  128  have received relatively more exposure since the graph  208  has extended further to the right of the exposure histogram  204  and since details  216  of the jar  210  are now becoming visible. The user viewing the view  504  ( FIG. 5C ) understands that the photosensitive sites  128  have received even more exposure since the graph  208  has extended almost fully to the right-hand side of the exposure histogram  204  and since the developing exposure image of the jar  210  is clearly discernible.  
      FIGS.  6 A-C are illustrative diagrams of another embodiment of the real-time exposure information comprising a preview image and an exposure histogram displayed on the display  126  ( FIG. 1 ). Here, the exposure histogram  204  is displayed over, superimposed on, or overlaid on a preview image of the jar  210 . The preview image of the jar does not significantly change through the series of displayed exposure histograms  204 . View  602  ( FIG. 6A ) indicates that the photosensitive sites  128  have detected a relatively small amount of light since the graph  208  is closer to the left-hand side of the exposure histogram  204  in the view  602 . View  604  ( FIG. 6B ) is based upon another non-destructive reading of the photosensitive sites  128  taken at a later time than the reading used to generate view  602 . Accordingly, the user viewing view  604  understands that the photosensitive sites  128  ( FIG. 1 ) have detected relatively more light since the graph  208  has extended further to the right of the exposure histogram  204 . View  606  ( FIG. 6C ) is based upon another non-destructive reading of the photosensitive sites  128  taken at a later time that the reading used to generate view  604 . Accordingly, the user viewing the view  606  understands that the photosensitive sites  128  ( FIG. 1 ) have detected relatively more light since the graph  208  has extended almost fully to the right-hand side of the exposure histogram  204 .  
      In yet another embodiment, the exposure information is displayed in the view of an electronic viewfinder  130  (EVF), viewable through viewfinder  122  ( FIG. 1 ). In one such embodiment, the exposure histogram is displayed concurrently with a preview image, similar to the illustrations of  FIGS. 6A-6B . In another embodiment, the exposure histogram is displayed concurrently with a developing exposure image, similar to the illustrations of  FIGS. 5A-5B . In yet another embodiment, the exposure histogram is displayed over the view coming through the optics of the viewfinder  122  using a ‘heads up’ display format. In yet another embodiment, a developing image (with or without an exposure histogram) is displayed on EVF  130 . It is appreciated that other embodiments displaying various types of exposure information using an electronic viewfinder  130  may be implemented similar to any of the embodiments displaying exposure information on display  126 .  
      Other types of exposure information may include indicia that corresponds to exposure of the captured image, wherein the indicia can be displayed on a “real-time” basis herein. Such indicia are determined based upon periodic non-destructive readings of the photosensor sites  128  during taken during the image capture exposure period. Non-limiting examples of such indicia include bar or pie chart animations, clock-like animations, or other graphical animations.  
       FIG. 7  shows a flow chart  700 , according to the various embodiments of real-time exposure information system  100  ( FIG. 1 ). The flow chart  700  shows the architecture, functionality, and operation of one possible embodiment for implementing the real-time exposure information logic  114  ( FIG. 1 ) such that light information from non-destructive reads of photosensor sites  128  is used to generate exposure information (exposure histograms and/or developing images), as described above in accordance with the present invention. An alternative embodiment implements the logic of flow chart  700  with hardware configured as a state machine. In this regard, each block may represent a module, segment or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that in some alternative implementations, the functions noted in the blocks may occur out of the order noted in  FIG. 7 , or may include additional functions. For example, two blocks shown in succession in  FIG. 7  may in fact be substantially executed concurrently, the blocks may sometimes be executed in the reverse order, or some of the blocks may not be executed in all instances, depending upon the functionality involved, as will be further clarified hereinbelow. All such modifications and variations are intended to be included herein within the scope of the present invention  
      The process begins at block  702 . At block  704 , a plurality of photosensitive sites residing in a photosensor on a periodic basis are non-destructively read. At block  706 , exposure information for each one of the non-destructive reads is generated. At block  708 , the exposure information is displayed after the exposure information is generated, such that the exposure information is displayed on the periodic basis. The process ends at block  710 .  
      Embodiments of the invention implemented in memory element  106  ( FIG. 1 ) may be implemented using any suitable computer-readable medium. In the context of this specification, a “computer-readable medium” can be any means that can store, communicate, propagate, or transport the data associated with, used by or in connection with the instruction execution system, apparatus, and/or device. The computer-readable medium can be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, device, or propagation medium now known or later developed.  
      It should be emphasized that the above-described embodiments are merely examples of implementations. Many variations and modifications may be made to the above-described embodiments. All such modifications and variations are intended to be included herein within the scope of this disclosure and protected by the following claims.