Abstract:
A system that provides a mechanism for processing, by a digital camera, of an originally captured image, prior to the image being saved in a format that has a reduced amount of information relative to the original image. The system allows a user to select a number of preferred image characteristics and interactively edit photographic images before the images are compressed and downloaded from the camera. More specifically, the system allows a user to select one or more preferred image characteristic settings, capture an image, preview the captured image after it has been processed in accordance with the selected settings, re-select one or more different image quality settings to ‘edit’ the image, and re-preview until the processed image is satisfactory.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates generally to digital cameras, and more particularly, to a system for providing user-selectable image processing options after image capture and prior to storing a final image in local memory.  
         BACKGROUND OF THE INVENTION  
         [0002]    Statement of the Problem  
           [0003]    Previously existing digital cameras record photographic images (i.e., ‘take pictures’) by the process of capturing a digital image, processing the image data, discarding the pre-processed image data, and saving the processed data as a photograph in a file in camera memory. In order to conserve on-board camera memory, the photograph (i.e., the processed image data) is typically saved in a compressed format that lacks some of the original image information.  
           [0004]    A user often needs to post-process the digital images, i.e., to modify some of the characteristics of the images, such as color, brightness, contrast, or other image characteristics. However, due to the expense of small, dense memory modules used in digital cameras, it is presently not economically feasible to save the pre-processed (original) image data for subsequent processing. Therefore, since all original image data is discarded in order to minimize memory usage, the only data available for subsequent editing is data which has been previously processed. This poses a problem with respect to the quality of post-processed photographs, due to the fact that the saved, previously processed, images have been compressed and therefore do not contain all of the original information that was present in the pre-processed image data.  
           [0005]    What is needed is a camera that allows a user to selectively and interactively customize and modify various characteristics of a captured image. In addition, it is desirable to allow a user to modify an image before the original image data is discarded, prior to any data compression or reduction, using the original, higher quality, pre-processed image data.  
           [0006]    Solution to the Problem  
           [0007]    The present system provides a mechanism for processing, by a digital camera, of an originally captured image, prior to the image being saved in a format that has a reduced amount of information relative to the original image. The present system allows a user to select a number of preferred image characteristics and interactively edit photographic images before the images are compressed and downloaded from the camera.  
           [0008]    More specifically, the digital camera incorporating the novel features of the present system allows a user to:  
           [0009]    (a) optionally select one or more preferred image characteristics settings (which have default values);  
           [0010]    (b) capture an image (i.e., ‘take a picture’);  
           [0011]    (c) review the captured image after it has been processed in accordance with the selected settings;  
           [0012]    (d) re-select one or more different image characteristics to ‘edit’ the image; and  
           [0013]    (e) repeat steps (c) and (d) until the processed image is satisfactory.  
           [0014]    At step (a), a user may set one or more image characteristics such as brightness (exposure), contrast, color balance, etc.  
           [0015]    In step (c), the camera processes the originally captured image and saves the processed image, but does not delete the original image. The camera displays the processed image on the camera&#39;s preview display (an LCD or other display device) so that the user may preview the image. If the user determines that the image requires further processing, then the user may edit the image by adjusting one or more image characteristics such as brightness, contrast, color balance, etc. After the image characteristics have been adjusted, a preview button is pressed, or alternatively, the image changes dynamically as the user makes the adjustments, and the image is re-processed in accordance with the adjusted image characteristics and displayed (previewed) again. When the user is satisfied with the processed image, the originally captured image is deleted when the shutter button is pressed to take the next picture.  
           [0016]    Heretofore, image processing was only possible offline, i.e., after images were downloaded from a camera to a computer, thus incurring degradation in the image quality of the post-processed compressed images. In fact, on-board, post-capture image processing was previously not available with any kind of camera, irrespective of the image quality issue. Although dozens of various types of digital cameras have been engineered, no previous camera has provided the capability of allowing a user to modify a captured (photographed) image using the originally captured image data, or to modify the image characteristics of a captured image before the image was downloaded from the camera.  
           [0017]    The present system provides the capability to selectively and interactively customize and modify various characteristics of a captured image before the image is downloaded to a computer for offline post-processing. The image may be modified (i.e., edited) before the original image data is discarded, prior to any data compression or reduction, using the original, higher quality, pre-processed image data. The resulting photographs are therefore of higher quality than photographs which have been preprocessed, compressed, and then post-processed after being downloaded. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]    [0018]FIGS. 1A and 1B are diagrams showing exemplary functional blocks in a digital camera used in the present system;  
         [0019]    [0019]FIG. 2 is a flowchart illustrating basic steps employed in carrying out the present system; and  
         [0020]    [0020]FIG. 3 is a flowchart illustrating, in greater detail, image processing functions shown in FIG. 2. 
     
    
     DETAILED DESCRIPTION  
       [0021]    [0021]FIGS. 1A and 1B are diagrams showing exemplary functional blocks in a digital camera used in the present system. FIG. 1A illustrates components of interest in a digital camera  101  programmed in accordance with the present system. As shown in FIG. 1, camera  101  comprises a light receiving device  107 , such as a CCD or CMOS imager, processor  110 , image processing hardware  105 , and an image memory module  102 . In an exemplary embodiment, light receiving device  107  is a CCD imager that detects light  126 , input through camera lens  127 , from the subject to be photographed.  
         [0022]    Camera  101  further comprises a preview display  104 , for example, an LCD device, a preview button or switch  103  for enabling the preview display, and an image characteristics input mechanism  111  including an image editing input  108  and an image settings input  109  for manual input of preferred image characteristics and image editing parameters, respectively. Processor  110  includes an image characteristics control component  120  and associated image settings data storage  121  which indicates user-selected image editing parameters including color balance  112 , contrast  113 , and brightness  114 , may also used in conjunction with the ‘preferred’ settings and preferred image characteristics settings, as explained below with respect to FIG. 1B.  
         [0023]    [0023]FIG. 1B illustrates, in further detail, certain exemplary aspects of image characteristics control function  120  and associated image settings data  121 . Input mechanism  111  includes an image editing input  108  for manual input of image editing parameters, and an image settings input  109  for manual input of preferred image characteristics that determine how the initially captured image is to be processed. The user may input the image settings via a selector switch or displayable menu, etc., both prior to capturing an image and after previewing a captured image, to edit the image.  
         [0024]    Preferred image characteristics include settings such as ‘sunny day’  115 , cloudy day’  116 , and other options  121 (n) such as ‘sports mode’, etc. Image characteristics control component  120  is coupled to input mechanism  111  for receiving user-selected image characteristics, which are converted into appropriate parameters that are stored in image settings data storage  121 . For example, ‘sunny day’ sets the color, contrast, and brightness to certain values that generally work well in sunlight. ‘Sports mode’, for example, causes selection of a faster than normal shutter speed and a commensurately larger aperture setting (i.e., lower ‘f stop’). The user can then further adjust the settings using color, contrast, and brightness settings. By default, an image is typically exposed using the EV value for the image, unless an image characteristics setting is selected that overrides the default exposure process. It is assumed that traditional, exposure algorithms, well-known in the art, yield adequate data for later processing.  
         [0025]    Block  121  is shown in dotted lines, indicating that image settings data  121  may be stored in memory that is shared between processor  110  and image processing hardware  105 , or the data may be stored in processor registers. Image processing hardware  105  operates on original data captured directly from light receiving device  107 , which is stored as original image data  132  in image memory  102 . Image processing hardware  105  functions in response to commands, from image characteristics control component  120 , to convert original image data  132  to compressed image data  142 , in accordance with parameters stored in image settings data storage  121 . Compressed image data  142  is also stored in image memory  102 . As part of the image processing procedure, the original image data  132  is processed by noise filter  106 , as necessary, to remove noise from the image. Image processing (initial processing and subsequent editing) is described below in greater detail with respect to FIG. 2. It should be noted that component functions shown as being integral to processor  110  may be optionally implemented by software or firmware. In any event, the functions performed by blocks  105 ,  106 , and  120  are initiated in response to commands from processor  110 .  
         [0026]    [0026]FIG. 2 is a flowchart illustrating basic steps employed in carrying out the present system. As shown in FIG. 2, at step  205 , the user ‘takes a picture’ with camera  101 , causing the camera to capture a digital image via light receiving device  107 . At step  210 , this original image is stored in image memory  102 , where it is retained for subsequent processing. The original image is typically saved in a mosaic pixel pattern, as described below with respect to FIG. 3.  
         [0027]    At step  215 , image control component  120  reads image characteristics input  111  (or, alternatively, uses default values) to determine how the originally captured image is to be processed. Parameters corresponding to these preferred image characteristics are then stored in image settings data storage  121 . Step  215  may be initiated in response to two different situations, wherein:  
         [0028]    ( 1 ) A user initially selects the preferred image characteristics that determine how the initially captured image is to be processed, via image setting input  109 , and takes a picture with camera  101 . If no image characteristics settings are selected by the user specifically for this picture, the previously selected settings, or alternatively, default values, are used by processor  110 /image processing hardware  105 .  
         [0029]    ( 2 ) After a picture has been taken, the original image data  132  is saved, and the image is initially processed; the user then presses preview button  103 , after having entered all of the desired image editing settings via image editing input  108 .  
         [0030]    At step  220 , the original image data stored in image memory  102  is processed by image processing hardware  105 , using the parameters in image settings data storage  121 . The processed image is typically a compressed 8 bit RGB image, as described below with respect to FIG. 3, which describes step  220  in greater detail. At step  222 , the processed image is stored in a file in compressed image data storage  142 , and at step  225  the processed image is displayed on preview display  104 .  
         [0031]    At step  230 , if the user decides that the processed image is acceptable, then no further action is by the user necessary, as the original image data  132  is deleted (at step  235 ) when the next picture is taken. In an alternative embodiment, the camera saves the data (in memory  102 ) from two or more original images to allow further on-board processing (re-editing) by the user subsequent to the image capture, after other pictures have been taken. If more than one original image is saved, the images may be deleted as necessary, depending on the amount of available memory  102 , as additional images are captured. If, at step  230 , the user decides that additional editing of the image is desirable, then editing (re-processing) of the originally captured image takes place, back at step  215 .  
         [0032]    [0032]FIG. 3 is a flowchart illustrating, in greater detail, image processing functions shown in step  220  of FIG. 2. At step  205  (in both FIGS. 2 and 3), a digital image is captured. As shown in FIG. 3, at step  300 , the original image data  301  is stored in original image data area  132 .  
         [0033]    At step  305 , CCD data  301 , detected by light receiving device  107 , is filtered by noise filter  106  to generate noise-filtered CCD data  302 . Depending upon how much the user wants to brighten or darken an image, this step may be omitted during the processing (editing) of certain images. If the user brightens an image a great deal, then additional noise filtering (after the initial image processing) may be necessary. Data from light receiving device  107  is typically in the format:  
                                                   R G R G R G . . .           G B G B G B . . .                      
 
         [0034]    where the data representation is R=red, G=green, and B=blue.  
         [0035]    At step  310 , the CCD data  302 , which is in a mosaic format, is converted into RGB data  303 . RGB Data is typically in the format:  
                                                   RGB RGB RGB . . .           RGB RGB RGB . . .                      
 
         [0036]    At step  315 , the RGB data is converted for non-linear display, typically for tone-mapping and contrast control. In an exemplary embodiment of the present system, 14 bit data is converted into 8 bit data at step  315 ; i.e., the data from step  310  is 14 bit RGB, and the data out of step  315  is effectively 8 bit RGB. In step  315 , RGB data  303  is converted for non-linear displays, per sRGB standard gamma correction. In one embodiment of the present system, a non-linear line of RGB data  303  is found for contrast and tone-mapping, and this line is merged with the standard non-linear line of the sRGB specification to make one line that is used in step  315 . In an alternative embodiment, three separate steps, including contrast adjustment  316 , preferred tone reproduction  317 , and sRGB gamma curve correction  318 , are performed on the RGB date  303 . Steps  315  and  316  are performed in accordance with the image processing settings acquired in step  215  in FIG. 2. RGB data  304  corrected in accordance with the sRGB gamma curve is stored in compressed image data storage  142  at step  320 , also used as display data for input to preview display  104 .  
         [0037]    Since the original image data  301  is not deleted until a subsequent exposure is taken, every step in FIG. 3 is performed every time the user changes one or more image characteristics settings. Original image data  301  must be converted, in accordance with the sRGB standard, in order to drive typical non-linear displays, such as preview display device  104 . This conversion is one reason why image information is lost when an image is processed. The present system, therefore, advantageously processes original image data  301  every time an image is edited.  
         [0038]    While exemplary embodiments of the present invention have been shown in the drawings and described above, it will be apparent to one skilled in the art that various embodiments of the present invention are possible. For example, the functional blocks shown in FIGS. 1A and 1B, as well as the specific sequence of steps described with respect to FIGS. 2 and 3, should not be construed as limited to the specific embodiments described herein. Modification may be made to these and other specific elements of the invention without departing from its spirit and scope as expressed in the following claims.