Patent Publication Number: US-2003231246-A1

Title: Digital photofinishing system utilizing user preference profiles

Description:
FIELD OF THE INVENTION  
       [0001] The present invention relates to a digital photofinishing system including a plurality of image processing modules employed within an image processing path for enhancement and manipulation of digital images.  
       BACKGROUND OF THE INVENTION  
       [0002] The Kodak Premier™ Image Enhancement System introduced in 1990 was a digital imaging application designed for the purposes of digitally manipulating digital images derived from a photographic film transparency material. In the Kodak Premier™ system, an original photographic film transparency material was scanned to produce a digital image. The user then manipulated the digital image to change one or more image characteristics including color balance and contrast. The manipulated digital image was then used to make an output photographic film transparency in the same form as the original but with the changed image characteristics. The user would bring up on an electronic display device a digital image derived from the original photographic film transparency. The user would then have a variety of controls available which would directly change one or more image processing parameters. As part of the image manipulation digital image processing procedures, the Kodak Premier™ system allowed the user to record the image processing parameters that were used to manipulate the digital image. The record of image processing parameters was stored on computer disk and could be retrieved for later processing. In addition, the retrieved image processing parameters, which were derived by manipulating a first digital image, could be applied to other digital images to produce a similar desired image look.  
       [0003] Other more current examples of digital imaging software packages, such as Adobe PhotoShop™ and Hewlett Packard DeskPro™, allow a user of the software to record image processing parameter(s) derived from manipulating a first digital image to be used to affect a second digital image. While these methods of saving image processing parameters for use with other digital images are powerful, they are also cumbersome due to the fact that a burden is placed on the user to learn how to use the particular image editing software package to advantage.  
       [0004] Traditionally, photographers using analog imaging equipment, such as photographic enlargers, would print variations of a photographic film transparency onto photographic paper using different exposure settings for the photographic enlarger. After viewing the resultant photographic prints, the photographer would then choose the optimum setting and make a final print. Digital imaging software applications have used this basic idea to present a user with multiple image renditions of a digital image viewed on an electronic display device. The user views the multiple images and selects the most pleasing. After the user has made a selection, the software application repeats the process with multiple image renditions of a different digital image. Thus, one by one the user is allowed to select the most pleasing image rendition of a manipulated digital image. While these applications are useful and intuitive for an uninitiated user to master, they are also slow and tedious to use due to the image by image presentation method employed.  
       [0005] In U.S. Pat. No. 5,300,974, Stephenson discloses a system that provides camera users with the ability to select color balance preferences for the reproduction of scene images captured on film. The system disclosed by Stephenson includes a user interactive station for displaying digital test images, derived from at least one predetermined scene type, which have been manipulated to have progressively different color balance characteristics. The user selects a displayed test image that he or she prefers and the system records the user&#39;s preference selection on a storage medium for transfer with the user&#39;s film to a photofinishing operation. In one embodiment, the user inserts a photographic film cartridge capable of recording additional information magnetically onto the photographic film into a specialized device for recording. The user-selected color balance information is then recorded magnetically onto the photographic film. The analog photofinishing system then retrieves and uses the user-selected color balance information from the film to make photographic prints for the user. In addition, the user-selected color balance information can be stored on a separate storage medium, such as a memory card, for direct transfer to the photofinisher.  
       [0006] While the method disclosed by Stephenson provides a means for customizing user color balance preferences for analog imaging systems, Stephenson is silent as to any extension of the method for a complicated digital imaging system. One problem is the complexity of the digital imaging system, wherein many different types of corrections can be made, including some that have an interactive effect upon others.  
       [0007] In commonly-assigned, copending U.S. patent application Ser. No. 09/742,553, entitled “Plurality of Picture Appearance Choices from a Color Photographic Recording Material Intended for Scanning” and filed Dec. 20, 2000 in the names of Sowinski et al, and Ser. No. 09/592,816, entitled “An Image Processing and Manipulation System” and filed Jun. 13, 2000 in the names of Szajewski et al (and which was published as European Patent Application EP 1 182 858 A2 on Feb. 27, 2002), the applicants disclose a method for a digital photofinishing system that extends the analog technology disclosed by Stephenson in U.S. Pat. No. 5,300,974 to a digital imaging system. The methods disclosed by these applications include processing images derived from scan-only photographic recording material and images derived from digital cameras. As disclosed by these applications, a selection of available appearances are presented to a user of the system as photographic prints displayed on a mailer, a brochure or an electronic device. Such image appearances include accurate color reproduction, portraiture, brilliant color, black-and-white, old fashioned sepia tones, selected levels of color intensity, selected levels of contrast, selected levels of detail reproduction, and selected levels of grain or noise. The user then selects from among these appearances and the images are rendered accordingly. The drawback of this system is that it fails to precisely isolate the effect of varying a single attribute on user preference, with other attributes contributing but held in a constant state.  
       [0008] In commonly-assigned, copending U.S. patent application Ser. No 09/549,356, entitled “Customizing a Digital Camera” and filed Apr. 14, 2000 in the names of Prabhu et al, (and which was published as European Patent Publication EP 1 058 450 A1 on Dec. 12, 2000), the applicants disclose a method for customizing the image processing operations performed by a digital camera. The camera customization software permits two or more users to customize the feature set (e.g., resolution, color correction, tone correction, sharpness and compression) of the digital camera and to store the corresponding firmware settings in the camera memory. When the camera is powered on, a list of users is displayed and the user selects their name using the camera interface. In response, the camera processor uses the appropriate firmware settings to provide the feature set for that particular user. During the process of initially establishing the feature set, the camera customization software may provide the user with sets of digital images, for example, three images at a time, and asks the user to choose which of the three images is preferred out of each set. The images have noticeable differences in flesh tones, sharpness, contrast, and other image attributes. While this application depicts multiple image renditions for a single processing control parameter, it does not precisely isolate the effect of varying a single attribute on user preference, with other attributes contributing but held in a constant state.  
       [0009] What is needed is a digital system for providing precise selection of user preferences for particular implementations of image processing modules. As mentioned above, none of the systems mentioned above precisely isolate the effect of varying a single attribute on user preference, particularly with other attributes contributing but held in a constant state.  
       SUMMARY OF THE INVENTION  
       [0010] It is an object of the invention to precisely isolate the effect of varying a single attribute on user preference, with other attributes contributing but held in a constant state.  
       [0011] It is a further object of the invention to provide a means for precisely selecting a user&#39;s preference for particular implementations of image processing modules, including without limitation modules for controlling image sharpness, noise removal, overall contrast, and color contrast, by presenting the user with multiple choices as variants of a single image quality attribute.  
       [0012] It is another object of the invention to provide a means for customizing photographic prints based on the physical size of the photographic prints requested, and the type of image capture device used to produce the source digital images.  
       [0013] The present invention is directed to overcoming one or more of the problems set forth above. In particular, the invention departs from the prior art by assuring that the test images used to ascertain preference are processed through the same image processing path as the final enhanced images, and, more specifically, are processed in the same image processing modules to isolate the effect of varying a single attribute on user preference, with other attributes contributing but held in a constant state.  
       [0014] Briefly summarized, according to one aspect of the present invention, the invention resides in a method for processing a digital image in order to provide an enhanced digital image comprising the steps of: a) providing an image processing path including a plurality of image processing modules designed to enhance the appearance of the digital image, wherein the processing effect of each image processing module is controlled by one or more processing control parameters; b) using the image processing path to process a test image; c) generating a plurality of available image renditions from the test image by varying one or more of the processing control parameters to control the image processing path of the test image; d) presenting the plurality of available image renditions to the user for viewing and selection by the user, whereby the selection of a particular image rendition determines the selection of a particular value of one or more processing control parameters that relate to a preference of the user; e) generating a user preference profile by storing the selected values of the processing control parameters relating to the preference of the user; and f) processing the digital image according to a user preference by using the user preference profile to customize the image processing path and to thereby produce an enhanced digital image from the digital image.  
       [0015] The advantage of the invention is that, by assuring that the test images used to ascertain preference are processed through the same image processing path as the final enhanced images, the test image renditions more effectively isolate the effect of varying a single attribute on user preference, thereby providing greater assurance that the final enhanced image will reflect the user preference noted in the chosen image renditions in the first place.  
       [0016] These and other aspects, objects, features and advantages of the present invention will be more clearly understood and appreciated from a review of the following detailed description of the preferred embodiments and appended claims, and by reference to the accompanying drawings. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0017]FIG. 1 is a block diagram showing a digital photofinishing system suitable for practicing the present invention.  
     [0018]FIG. 2 is a block diagram showing the details of the general control computer shown in FIG. 1.  
     [0019]FIG. 3 is a block diagram showing the details of the image processing path of the digital image processor shown in FIG. 1.  
     [0020]FIG. 4 is a block diagram showing further details of the general control computer shown in FIG. 1.  
     [0021]FIG. 5 is a block diagram showing further details of the image processing modules used in the digital image processor shown in FIG. 1. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
     [0022] The present invention relates to a digital photofinishing system that provides a means for customizing the appearance of photographic prints based on the personal preferences of an individual user. The image processing path employed by the digital photofinishing system according to the present invention includes a plurality of image processing modules that can be activated with different control parameter settings. These control parameter settings are varied to produce display materials that the user can select from. The user makes preference selections which are recorded by the digital photofinishing system and used to produce photographic prints from the user&#39;s images.  
     [0023] The digital photofinishing system shown in FIG. 1 includes multiple image capture devices  10   a,    10   b,  and  10   c,  a digital image processor  20 , and multiple image output devices  30   a  and  30   b.  The digital photofinishing system can include a monitor device  50  and an input control device  60 , such as a keyboard. For example, the image capture device  10   a  may be a photographic film transparency scanner for generating a digital image from a photographic film transparency. The digital image processor  20  provides the means for processing the digital images to produce enhanced digital images. These enhanced digital images are received by an image output device  30   a,  such as a digital printer that produces photographic prints or a display that produces softcopy images. The digital image processor  20  processes an input digital image to produce an output digital image that has been enhanced in some manner and prepared for the output device  30   a.  The general control computer  40  receives information from, and transmits information to, the digital image processor  20  that affects the manner in which digital images are processed. An offline memory device  70  is also connected to the general control computer  40  and can be used for the purposes of storing and receiving information. The monitor device  50  is connected to the general control computer  40 , which allows the operator of the digital photofinishing system to monitor the system activity.  
     [0024] A user  80  (an individual person or persons) views the processed images produced by one or more of the output devices  30   a,  makes selections as to personal preference, and enters the selections via the input control device  60 . A user  90  (another individual person or persons) submits a set of digital images to be processed by the digital photofinishing system and enters information to the digital photofinishing system via the input control device  60 .  
     [0025] The details of the interactions of the blocks shown in FIG. 1 are shown in more detail in FIG. 2. The digital image processor  20  includes a plurality of image processing modules, each module having been designed to enhance the appearance of the processed digital images. The individual image processing modules included in the digital image processor  20  are controlled by at least one processing control parameter  122 . The collection of the plurality of image processing modules and their associated processing control parameters constitutes a digital processing path (as further shown in FIG. 3) which when applied to an input digital image produces an output digital image. In the preferred embodiment, a set of processing control parameters  122  is produced by the control parameter generator  120 . The digital image processor  20  receives a set of test digital images  101  which have been prepared as examples of images for which typical users express varied opinions. Examples of subject matter included in the test digital images  101  are portrait scenes, landscape scenes, flash scenes, bright sunny day scenes, sunset scenes, etc. The digital image processor  20  uses the set of processing control parameters  122  to vary the processing effects of the image processing modules, which are applied to the test digital images  101  to produce a set of presentation digital images  102 . A presentation digital image  102  is the result of processing one of the test digital images  101  with the image processing modules included in the digital image processor  20  with a particular configuration of the processing control parameters  122 .  
     [0026] The presentation digital images  102  are received by the image output device  30   a,  which produces a viewable image. The preferred embodiment of the present invention uses a digital printer as the image output device  30   a  due to its high image quality. As an alternative embodiment, the present invention s uses an electronic display device for the image output device  30   a.  Viewing the presentation digital images  102  on an electronic display device allows an alternative embodiment of the present invention to be used with the user  80  remote from the digital photofinishing system. The user can be at home, at a kiosk, or connected wirelessly via an internet connection. Both the electronic display device used by this alternative embodiment and the photographic prints used by the preferred embodiment are examples of different display media that allow the user to view and select from the presentation digital images  102 .  
     [0027] The presentation digital images  102  represent different image renditions, i.e., different possible image looks that vary in one or more image quality characteristics that are made available to the user  80  via the digital photofinishing system. Thus each presentation digital image  102  represents an image rendition that could be applied to the user&#39;s personal images. The details of the available image renditions that the present invention can make available to a user  80  are given herein below. Generally, image renditions differ from one another typically in contrast, color, or the treatment of spatial detail.  
     [0028] The user  80  views the presentation digital images  102  as prepared by the image output device  30   a  and makes selections as to the user&#39;s preferences. The user preference profile generator  130  receives the selections made by the user  80  along with a user identification tag  82 . The present invention uses the user&#39;s personal name as the user identification tag  82 ; however, other forms of unique information could be used to equivalent effect, such as the user&#39;s social security number. The important aspect of the user identification tag  82  is that it must allow the digital photofinishing system to uniquely identify the user&#39;s preferences. The user preference profile generator  130  also receives the processing control parameters  122  that relate to both the individual image processing modules included in the digital image processor  20  and the user&#39;s preference selections. The user preference profile generator  130  produces a user preference profile  84   a  which includes the user&#39;s user identification tag  82  and the processing control parameters relating to the user&#39;s selections. Other users perform the same task of viewing images, making selections, and entering the information into the general computer  40 . Thus the digital photofinishing system records and stores in a data base a plurality of user preference profiles  84   a  that relate to the visual preferences of users.  
     [0029] In a preferred embodiment, the photographic prints produced with the presentation digital images  102  are assembled into a preference brochure  110 . On each page of the preference brochure the user  80  is presented with two or more prints from which a single choice of preference must be made. The prints on each page are numbered as 1, 2, etc. The user  80  records his or her selections by indicating the number of the preferred print on a user preference form. The user preference form is then handed to the digital photofinishing system operator and entered into the general computer  40  or the user can enter the information directly. Table 1 is an example of a user preference form.  
                           TABLE 1                                       George Washington           user   Selection:                          Page 1 (1, 2, 3, 4, 5)   3           Page 2 (1, 2, 3, 4, 5)   4           Page 3 (1, 2, 3)   1           Page 4 (1, 2)   2           Page 5 (1, 2, 3, 4)   4           Page 6 (1, 2, 3, 4)   2                      
 
     [0030] As can be seen in table 1, the pages of the preference brochure do not need to have the same number of prints.  
     [0031] In an alternative embodiment of the present invention, the photographic prints produced with the presentation digital images  102  are assembled on poster boards to be displayed, i.e., a large sheet of material to which the photographic prints are attached. This method allows for a greater assortment of prints to be displayed and viewed simultaneously. Also a consideration is the fact that more than one person can easily view the poster boards at a time.  
     [0032] In another alternative embodiment of the present invention, the enhanced digital images derived from the test digital images are displayed on an electronic display device. The user makes selections by clicking with an input control device on the preferred image and the system software records the user selections to produce an electronic version of the user preference form. With this embodiment, the user can use the digital photofinishing system while connected via a remote computer connection.  
     [0033] In a still further alternative embodiment of the present invention, a preference brochure is printed and mailed to the user. The user then connects to the digital photofinishing system via a remote computer connection and enters his or her preference selections into a software program. The software program displays diagrams with rectangles representing the layout of images pertaining to each page of the preference brochure. The user makes selections by clicking with an input control device on the corresponding rectangles. With this embodiment, while the user can still make use of the digital photofinishing system while connected via a remote computer, he or she can rely on the photographic prints of the preference brochure to visualize the effects. This is particularly useful for photographic prints relating to sharpness and noise attributes since image structure-related image quality attributes are sometimes not well reproduced with electronic display devices.  
     [0034] The image processing path of the digital image processor  20  shown in FIGS. 1 and 2 is shown in more detail in FIG. 3. The digital image processor  20  includes a plurality of image processing modules  140   a,    140   b,    140   c,    140   d,    140   e,  and  140   f,  which collectively comprise an image processing path. Each image processing module has one or more corresponding processing control parameters shown by  122   a,    122   b,    122   c,    122   d,    122   e,  and  122   f,  respectively. The first image processing module  140   a  receives the input digital images  107  one at a time. For each input digital image  107 , the image processing module  140   a  processes the input digital image  107  and produces a modified digital image. Image processing module  140   b  receives the modified digital image from image processing module  140   a  and modifies it further. The processing continues with the succession of image processing modules until the last image processing module, shown as image processing module  140   f,  produces an output digital image  108 .  
     [0035] The control parameter generator  120  shown in FIG. 2 is configured such that the permutations of photographic prints that appear on a given page of the preference brochure corresponds to image processing variations relating to a single image processing module. For example, the print examples on page one of the preference brochure are produced by setting the values of control parameters  122   b,    122   c,    122   d,    122   e,  and  122   f  to the digital photofinishing system default values and varying the value of processing control parameter  122   a  through a range of numerical values. Each of the photographic print examples on page one of the preference brochure therefore relates to a different effect achievable with different values of the processing control parameter  122   a.  Similarly, the print examples on page two of the preference brochure are produced by setting the values of control parameters  122   a,    122   c,    122   d,    122   e,  and  122   f  to the digital photofinishing system default values and varying the value of processing control parameter  122   b  through a range of numerical values. Hence each of the photographic print examples on page two of the preference brochure therefore relates to a different effect achievable with different values of the processing control parameter  122   b.  Thus each page of the preference brochure relates to the effects achievable with different values of a different image processing module.  
     [0036] As described above, the user preference profile  84   a  includes the selection preferences made by the user  80 , each of which is a particular permutation of a processing control parameter  122 . Table 2 shows an example user preference profile  84   a  that corresponds to the user preference form shown in Table 1.  
                   TABLE 2                       User identification tag:   George Washington       Processing control parameter   Value of processing control parameter                  122a   permutation value 3       122b   permutation value 4       122c   permutation value 1       122d   permutation value 2       122e   permutation value 4       122f   permutation value 2                  
 
     [0037] The permutation values indicated in Table 2 represent the individual values for the processing control values  122   a,    122   b,    122   c,    122   d,    122   e,  and  122   f  that were selected by the user  80  to generate the photographic prints.  
     [0038] As shown in FIG. 4, the present invention uses a data base  84  of recorded user preference profiles to process digital images  105  received by a particular user according to the particular user&#39;s preferences. Referring to FIG. 4, the general control computer  40  stores the data base  84  of user preference profiles as indicated by the user preference profile blocks  84   a,    84   b,  and  84   c.  These user preference profiles have been previously generated using the method described above. A user  90  of the digital photofinishing system provides the system with his or her user identification tag  93  which should be the same or nearly the same as the user identification tag  82  that the user  90  provided when he or she filled out a user preference form. A user preference profile selector  140  receives the user identification tag  93  and uses it to select the user preference profile associated with the user  90  from the data base  84  of user preference profiles. The user&#39;s user preference profile  84   a  is selected by comparing the received user identification tag  93  with the user identification tags  82  of all the user preference profiles in the data base. When the user preference profile selector  140  finds a match, it retrieves the user&#39;s preference profile and assigns it to the user preference profile  95 .  
     [0039] The digital image processor  20  also receives a set of source digital images  105  from the user  90 , and an indication, e.g., to the operator of the digital photofinishing system, of the quantity and the size of photographic prints to be made from the source digital images  105 . The digital image processor  20  receives the user preference profile  95 , which indicates the user&#39;s preferences, and processes the set of source digital images  105  using the processing control parameters  122  from the user preference profile  95  to generate a set of enhanced digital images  106 . The enhanced digital images  106  are then received by the image output device  30   a  which produces a set of photographic prints. The user  90  receives the photographic prints and provides payment to the digital photofinishing operator.  
     [0040] In an alternative embodiment of the present invention, the enhanced digital images  106  are stored on a storage medium  96  such as a floppy disk or compact optical disk. For this embodiment, the user  90  has the option of choosing not to produce photographic prints.  
     [0041] In another alternative embodiment of the present invention, the enhanced digital images  106  are made available to the user  90  via a computer internet connection  97 . For this embodiment, the user  90  has the option of choosing not to produce photographic prints. Instead, the user  90  pays for the service of access to the set of enhanced digital images  106 . The user  90  can down load the enhanced digital images  106  from the general control computer  40  via a wired or wireless internet connection to the user&#39;s computer  98 .  
     [0042] In still another alternative embodiment of the present invention, the user  90  receives a software implementation of the digital image processor  20  and general control processor  40  that can be executed on the user&#39;s computer  98 . In this embodiment the user  90  makes payment, e.g., using a credit transaction over the internet connection  97 , to the digital photofinishing system for the privilege to use the software implementation on the user&#39;s computer  98 . In this implementation, the user  90  produces a set of enhanced digital images  106  from a set of source digital images  105 . The set of enhanced digital images  106  can be used to make photographic prints on a digital printer. However, the user  90  can transmit the set of enhanced digital images  106  to the photofinishing system, where photographic prints can be made using the image output device  30   a.  For this embodiment of the present invention, the processing of the source digital images  105  is performed on the user&#39;s computer  98  instead of the digital image processor  20 . The user  90  can be charged less than the normal payment rate for this embodiment since the digital photofinishing system required less in the way of system resources to produce the photographic prints.  
     [0043] The digital image processor  20  employed by the present invention includes a variety of image processing modules that can customize the image quality of the resultant photographic prints produced. In particular, as shown in FIG. 5, the present invention includes a noise reduction module  210 , a color balance module  220 , a color contrast module  230 , a luminance contrast module  240 , and a spatial sharpening module  250 . Each image processing module receives a digital image, modifies the pixel values of the image, and passes the modified digital image to the next image processing module in the sequence. While the image processing modules shown in FIG. 5 have a specific sequential order, it is possible to use the same image processing modules in a different sequential order and still achieve good results. However, experimentation has shown that the best position for the noise reduction module  210  is at the beginning of the sequence of image processing modules. This is mainly due to the fact that the best results are obtained when the noise is removed from a digital signal (image) before it is enhanced for contrast due to the fact that the contrast enhancement modules can amplify the existing noise. Similarly, the best position for the spatial sharpening module  250  is at the end of the sequence of image processing modules.  
     [0044] For each image processing module, the processing control parameter(s) are varied over a numerical range such that the resulting photographic prints differ from one another in approximately equal perceptual increments. That is, for each image processing module, the series of photographic prints produced by varying the corresponding processing control parameter (when ordered sequentially with respect to perceptual degree of effect) should be perceived as equally noticeable changes. Thus for the example described above and depicted in Table 1, the photographic prints resulting from the first and second permutation value of processing control parameter  122   a  (page 1) should appear to most observers to be approximately as different as the photographic prints resulting from the second and third permutation value of processing control parameter  122   a,  and so on for the other processing control parameters  
     [0045] The present invention uses digital images comprised of one or more digital image channels. Each digital image channel is comprised of a two-dimensional array of pixels. Each pixel value relates to the amount of light received by an imaging device corresponding to the geometrical domain of the pixel. For color imaging applications, a digital image will typically comprise red, green, and blue digital image channels. Other configurations can also be practiced, e.g. cyan, magenta, and yellow digital image channels. For monochrome applications, the digital image comprises one digital image channel. Although the present invention describes a digital image channel as a two dimensional array of pixel values arranged by rows and columns, those skilled in the art will recognize that the present invention can be applied to mosaic (non-rectilinear) arrays with equal effect.  
     [0046] The present invention uses a noise reduction module  210  which employs a modified version of the Sigma filter, as described by Jong-Sen Lee in the journal article  Digital Image Smoothing and the Sigma Filter,  Computer Vision, Graphics, and Image Processing Vol. 24, p. 255-269, 1983. The values of the pixels contained in a sampled local region, n by n pixels, where n denotes the length (number) of pixels in either the row or column direction, are compared with the value of the pixel of interest, e.g., a center pixel. Each pixel in the sampled local region is given a weighting factor of one or zero based on the absolute difference between the value of the pixel of interest and the local region pixel value. If the absolute value of the pixel value difference is less than or equal to a threshold ε, the weighting factor is set to one. Otherwise, the weighting factor is set to zero. The numerical constant E is set to two times the expected noise standard deviation. Mathematically the expression for the calculation of the noise reduced pixel value is given as equation (1)  
                 q   mn     =       ∑   ij            a   ij            p   ij     /       ∑   ij            a   ij                   and                               
            a   ij     =       1                 if                |       p   ij     -     p   mn       |     &lt;=   ɛ              
            a   ij     =       0                 if                |       p   ij     -     p   mn       |     &gt;   ɛ                 (   1   )                       
 
     [0047] where p ij  represents the ij th  pixel contained in the sampled local region, p mn  represents the value of the pixel of interest located at row m and column n, a ij  represents a weighting factor, and q mn  represents the noise reduced pixel value. Typically, a rectangular sampling region centered about the center pixel is used with the indices i and j varied to sample the local pixel values.  
     [0048] The threshold E parameter is given by equation (2), as follows:  
     ε=Sfacσ n    (2)  
     [0049] where σ n  represents the noise standard deviation of the source image. The calculation of the noise reduced pixel value q mn  as the division of the two sums is then calculated. The parameter Sfac is the processing control parameter that is used to vary the degree of noise reduction. The present invention uses values of 1.25, 1.50, 1.75, 2.00, 2.25, and 2.50 as values to vary the effects possible with the noise reduction module  210 . The resulting presentation digital images  102  are noticeably different to most observers. Experimentation has found that the system default value (optimum value) for the parameter Sfac is 1.75.  
     [0050] The color balance module  220  used by the present invention has the effect of imparting an overall color cast to digital images. The present invention processes digital images in a logarithmic pixel value domain, i.e. the pixel values bear a logarithmic relationship to the original scene intensities from which the pixel values are derived. Therefore, a numerical constant added to the pixel values will result in an overall color cast change when the processed digital images are viewed on an image output device.  
     [0051] The input digital images to the color balance module  220  are in a red, green, and blue representation, i.e., they include a red, green, and blue digital image channel. The color balance module  220  converts the input digital image into a luminance-chrominance representation wherein the following matrix is applied to the red, green, blue pixel data resulting in three digital image channels, a luminance digital image channel (L), a green-magenta (GM) digital image channel, and an illuminant (ILL) digital image channel. The color matrix transformation relating the input and output pixel values is as follows (equation (3)):  
                     L   mn     =       0.333                   R   mn       +     0.333                   G   mn       +     0.333                   B   mn                       GM   mn     =         -   0.25                     R   mn       +     0.50                   G   mn       -     0.25                   B   mn                       ILL   mn     =         -   0.50                     R   mn       +     0.50                   B   mn                       (   3   )                       
 
     [0052] where R mn , G mn , and B mn  refer to the pixel values corresponding to the red, green, and blue digital image channels located at the m th  row and n th  column and L mn , GM mn , and ILL mn  refer to the processed pixel of the luminance, green-magenta, and illuminant digital image channels respectively. Those skilled in the art will recognize that the exact values used for coefficients in the luminance/chrominance color matrix transformation can be altered and still yield substantially the same effect.  
     [0053] The processing control parameter for the color balance module  220  is ill o  which relates to the illuminant (ILL) digital image channel. The processing control parameter ill o  changes the overall color balance of the processed images in the “warm-cool” axis of color space. Positive values for the ill o  parameter will cause the processed images to be “cooler” looking, i.e., having an overall color cast that is more toward the blue-cyan color than the original. Conversely, negative values for the ill o  parameter will cause the processed images to be “warmer” looking, i.e., having an overall color cast that is more toward the red-yellow color than the original. The color balance module modifies the digital image pixel data using equation (4)  
       ILL′   mn   =ILL   mn   +ill   o    (4)  
     [0054] where ILL mn  represents the input illuminant digital image channel pixel value and ILL′ mn  represents the processed illuminant digital image channel pixel value. The system default value for the processing control parameter ill o  is 0.0. The present invention uses positive and negative values for ill o  to span a range of effects including “warm” and “cool” photographic prints. The actual numerical values for the parameter ill o  depend on the computer software implementation. However, the present invention sets different values for ill o  to correspond to just noticeable changes in the resultant photographic prints, i.e., each of the viewed representations of the resulting presentation digital images  102  should be discernibly different to most observers.  
     [0055] The color contrast module  230  receives the processed digital image from the color balance module  220 . The processing control parameter for the color contrast module  230  is represented by a variable γ c . The color contrast module  230  modifies the pixel values of the luminance-chrominance representation by multiplying the green-magenta and illuminant digital image channel pixel values by the variable γ c  as in equations (5):  
     GM′ mn =GM mn γ c    
     ILL′ mn =ILL mn γ c    (5)  
     [0056] where GM′ mn  and ILL′ mn  represent the processed pixel values, and GM mn  and ILL mn  represent the input pixel values to the color contrast module  230 . The system default value for the variable γ c  is set to 1.0. The present invention uses values 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, and 1.4 for the processing control variable γ c . With these values for the variable γ c , most observers will notice differences between all of photographic prints made with the processed digital images. The present invention uses an asymmetric set of values about the system default value for the processing control parameter since some users prefer highly boosted color contrast (corresponding to higher values of the variable γ c ) while other users prefer a more subtle rendition.  
     [0057] The luminance contrast module  240  receives the processed digital image from the color contrast module  220 . The processing control parameter for the luminance contrast module  240  is represented by a variable γ b . The luminance contrast module  240  modifies the pixel values of the luminance-chrominance representation by multiplying the luminance digital image channel pixel values by the variable γ b  as equation (6):  
     L′ mn =L mn γ b    (6)  
     [0058] where L′ mn  represents the processed pixel values and L mn  represents the input pixel values to the luminance contrast module  240 . The system default value for the variable γ b  is set to 1.0. The present invention uses values 0.8, 0.9, 1.0, 1. 1, and 1.2 for the processing control variable γ b . With these values for the variable γ b , most observers will notice differences between all of photographic prints made with the processed digital images. The present invention uses a symmetric set of values about the system default value for the processing control parameter since users appear to be evenly split between preferring images of high contrast to images of low contrast.  
     [0059] The spatial sharpening module  250  receives the processed digital image from the luminance contrast module  240 . The processing control parameter for the spatial sharpening module  250  is represented by a variable γ s . The present invention uses a form of unsharp masking to achieve a range of spatial sharpening effects. The luminance digital image channel is spatially filtered with a low-pass Gaussian filter with the standard deviation parameter of the Gaussian filter set to correspond to 2.5 pixels. The low-pass filtered component (lp) of the luminance digital image channel is subtracted from the luminance digital image channel yielding a high-pass component (hp) as in equation (7):  
       hp   mn   =L   mn   −lp   mn    (7)  
     [0060] Changes to the spatial detail of the processed digital images is imparted by multiplying the high-pass component values by the process control variable γ s  as in equation (8):  
       L′   mn   =hp   mn   δ   s   +lp   mn    (8)  
     [0061] where L′ mn  represents the processed pixel values of the spatial sharpening module  250 . The system default value for the variable γ s  is set to 1.2 which amplifies the level of spatial detail. The optimum system default value is application specific and, in particular, depends on the spatial imaging characteristics of the digital printer used. The present invention uses values 1.0, 1.1, 1.2, 1.3, and 1.4 for the processing control variable γ s . With these values for the variable γ s , most observers will notice differences between all of photographic prints made with the processed digital images.  
     [0062] The optimum values for the processing control parameters, from a user preference perspective, can depend on the physical size of the photographic prints. Typical photographic print sizes include 3×5, 4×6, 5×7, 8×12, 11×14, and 16×20 where the numbers represent print dimensions in inches. In one embodiment of the present invention, a preference brochure is produced for each size photographic print. The user can make selections as to preference using the preference brochure that relates to the size of photographic prints that he or she typically desires. However, users are encouraged to fill out a user preference form for each size of photographic prints. For this embodiment of the present invention, an enlargement identification tag is recorded with the user preference form and consequently with the user preference profile  84   a.  Thus additional sets of processing control parameters  122  are recorded within the user preference profile  84   a,  i.e., one set of processing control parameters  122  for each size of photographic print. When the user orders photographic prints from a set of source digital images  105 , the user also specifies the size of the photographic prints desired. If the user&#39;s user preference profile contains information relating to the different size photographic prints specified, the digital photofinishing system will use the corresponding set of processing control parameters  122  within the user preference profile  84   a  uniquely for each size of photographic print requested. Thus, the present invention provides a means for customizing the image quality of photographic prints made from digital images based on the user preference profile  84   a  and the size of the photographic print requested.  
     [0063] The optimum values for the processing control parameters can also depend on the source of the digital images. For example, a user can request photographic prints from a digital camera, from still image frames from a video camera, from a photographic film transparency, or from a photographic print.  
     [0064] The image structure, i.e., the noise and sharpness characteristics, of images derived from these different sources can be quite different. To accommodate user preferences that may be different for different sources of digital images, in another embodiment of the present invention, a preference brochure is produced for each source of digital images. Although the preferred embodiment of the present invention uses a pre-printed preference brochure  110 , in this alternative embodiment the user  80  can supply the digital photofinishing system with the test images  101  necessary to generate the preference brochure  110 . For this alternative embodiment, the user preference profile  84   a  records a source type identification tag that uniquely identifies the source of the digital images for which the user is making preference selections.  
     [0065] Thus additional sets of processing control parameters  122  are recorded within the user preference profile  84   a,  i.e., one set of processing control parameters  122  for each source of the digital images. When the user orders photographic prints from a set of source digital images  105 , the user also specifies the source type identification tag associated with the source digital images  105 . If the user&#39;s user preference profile contains information relating to the source type identification tag specified, the digital photofinishing system will use the corresponding set of processing control parameters  122  within the user preference profile  84   a  uniquely for each source type. Thus the present invention provides a means for customizing the image quality of photographic prints made from digital images based on the user preference profile  84   a  and the source of the digital images  105 .  
     [0066] While a single user preference profile provides a means of customizing the image rendition for a particular user, some users desire a further level of customization. For example, a user may have family members that have significantly difference preferences. For some users, preference depends on the photographed subject matter. For example, a user may prefer that landscape scenes be processed with boosted color contrast for emphasis. The same user may prefer a much more subtle color contrast for a portrait scene in order to de-emphasize the red color in flesh tones.  
     [0067] In an alternative embodiment of the present invention, a user of the digital photofinishing system is encouraged to fill out more than one user preference form. On each user preference form there is a reserved field, a user rendition tag, that allows the user to supply a word or phrase that uniquely identifies the individual user preference form. For example, a user can give a first user preference form the user rendition tag of “scenic” and a second user preference form the user rendition tag of “portraits”. The digital photofinishing system creates a unique set of processing control parameters relating to each user preference form. Thus, additional sets of processing control parameters  122  are recorded within the user preference profile  84   a,  i.e., one set of processing control parameters  122  for each user preference form. The next time the user becomes a user providing payment for services, as a user he or she supplies to the digital photofinishing system the user rendition tag, along with the user identification tag and the source digital images. The digital photofinishing system selects the user preference profile based on the user identification tag as described above, and further selects the corresponding set of processing control parameters relating to the user rendition tag. Thus, a user of the digital photofinishing system is provided with a further level of customization at the point of sale. Additionally, if user desires, a user rendition tag can be supplied with each individual source digital image to be processed.  
     [0068] The invention has been described in detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.  
     [0069] Parts List  
     [0070] 10   a  image capture device  
     [0071] 10   b  image capture device  
     [0072] 10   c  image capture device  
     [0073] 20  digital image processor  
     [0074] 30   a  image output device  
     [0075] 30   b  image output device  
     [0076] 40  general control computer  
     [0077] 50  monitor device  
     [0078] 60  input control device  
     [0079] 70  offline memory device  
     [0080] 80  user  
     [0081] 82  user identification tag  
     [0082] 84   a  user preference profile  
     [0083] 84   b  user preference profile  
     [0084] 84   c  user preference profile  
     [0085] 90  user  
     [0086] 93  user identification tag  
     [0087] 95  user preference profile  
     [0088] 96  storage medium  
     [0089] 97  internet connection  
     [0090] 98  user computer  
     [0091] 101  test digital image  
     [0092] 102  presentation digital image  
     [0093] 105  source digital image  
     [0094] 106  enhanced digital image  
     [0095] 107  input digital image  
     [0096] 108  output digital image  
     [0097] 110  preference brochure  
     [0098] 120  control parameter generator  
     [0099] 122   a  processing control parameter  
     [0100] 122   b  processing control parameter  
     [0101] 122   c  processing control parameter  
     [0102] 122   d  processing control parameter  
     [0103] 122   e  processing control parameter  
     [0104] 122   f  processing control parameter  
     [0105] 130  user preference profile generator  
     [0106] 140   a  image processing module  
     [0107] 140   b  image processing module  
     [0108] 140   c  image processing module  
     [0109] 140   d  image processing module  
     [0110] 140   e  image processing module  
     [0111] 140   f  image processing module  
     [0112] 210  noise reduction module  
     [0113] 220  color balance module  
     [0114] 230  color contrast module  
     [0115] 240  luminance contrast module  
     [0116] 250  spatial sharpening module