Patent Publication Number: US-11042972-B2

Title: Image processing apparatus, and non-transitory computer readable medium for reducing undesirable effect during image capturing

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2018-177197 filed Sep. 21, 2018. 
     BACKGROUND 
     (i) Technical Field 
     The present disclosure relates to an image processing apparatus, and a non-transitory computer readable medium. 
     (ii) Related Art 
     Japanese Unexamined Patent Application Publication No. 2010-74693 discloses a digital camera. The digital camera includes an electronic flash device that irradiates an object with flash light, an imaging device that consecutively acquires a first image that is captured with the object not irradiated with flash light, and a second image that is captured with the object irradiated with flash light, an image correlation detection circuit that detects an image portion of each image having no correlation by comparing the first image with the second image, and a correction image generating circuit that generates a third image by extracting from the second image the image portion having no correlation, removes from the first image the image portion having no correlation, and embedding the image portion extracted from the second image into the corresponding portion of the first image from which the image portion having no correlation has been removed. 
     SUMMARY 
     Aspects of non-limiting embodiments of the present disclosure relate to an image processing apparatus and a non-transitory computer readable medium. The image processing apparatus acquires an image that is captured in a more reduced effect that is caused with a light irradiating unit irradiating an object with light in comparison with an image of the object that is captured with the light irradiation unit irradiating the object with light at one time only. 
     Aspects of certain non-limiting embodiments of the present disclosure address the above advantages and/or other advantages not described above. However, aspects of the non-limiting embodiments are not required to address the advantages described above, and aspects of the non-limiting embodiments of the present disclosure may not address advantages described above. 
     According to an aspect of the present disclosure, there is provided an image processing apparatus. The image processing apparatus includes a receiving unit that receives a first image that is captured with an object irradiated with light from a light irradiating unit and a second image that is captured with the object not irradiated with light from the light irradiating unit, and a generating unit that generates a composite image by adjusting brightness of a whole area of the second image such that brightness at a specific location in the first image is approximately equal to brightness at a corresponding specific location in the second image, and by replacing in the first image a pixel value of a pixel that is affected by light irradiation by the light irradiating unit with a pixel value of a pixel in the second image that has been adjusted in brightness. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Exemplary embodiments of the present disclosure will be described in detail based on the following figures, wherein: 
         FIG. 1A  a perspective external view of an image processing apparatus of an exemplary embodiment, and  FIG. 1B  is a perspective view illustrating how an object is photographed using the image processing apparatus; 
         FIG. 2  illustrates the state of the object that is photographed with the object not irradiated with light from a flashing device; 
         FIG. 3  illustrates the state of the object that is photographed with the object irradiated with light from the flashing device; 
         FIG. 4  illustrates a hardware configuration of the image processing apparatus of the exemplary embodiment; 
         FIG. 5  is a functional block diagram of the image processing apparatus of  FIG. 4 ; 
         FIG. 6  is a flowchart illustrating an image composing process performed by the image processing apparatus of the exemplary embodiment; 
         FIG. 7A  illustrates the state of a first image that is obtained by capturing an image of the object with the object irradiated with flash light and then by projective-transforming the image, and  FIG. 7B  illustrates the state of a second image that is obtained by capturing an image of the object with the object not irradiated with the flash light and then by projective-transforming the image; 
         FIGS. 8A through 8C  illustrate the concept of the image composing process of the exemplary embodiment, wherein  FIG. 8A  illustrates luminance of a pixel row of the first image of  FIG. 7A  across line VIIIA-VIIIA,  FIG. 8B  illustrates luminance of pixel rows of the first and second images with brightness of the second image adjusted, and  FIG. 8C  illustrates luminance of a pixel row of a composite image into which the first and second images are combined; 
         FIG. 9  illustrates the concept of an image processing system of a modification of the exemplary embodiment of the disclosure; 
         FIG. 10  is a functional block diagram illustrating a terminal device of the modification of the exemplary embodiment; 
         FIGS. 11A and 11B  illustrate the configuration of an image processing server of the image processing system of the modification of the exemplary embodiment, wherein  FIG. 11A  illustrates the hardware configuration of the image processing server, and  FIG. 11B  illustrates the functional block diagram of the image processing server; 
         FIG. 12  is a flowchart illustrating the process of the terminal device of the modification of the exemplary embodiment; and 
         FIG. 13  is a flowchart illustrating the process of the image processing server of the modification of the exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     An image processing apparatus  20  of an exemplary embodiment of the disclosure is described with reference to  FIGS. 1A and 1B .  FIG. 1A  is a perspective external view of the image processing apparatus  20  of the exemplary embodiment, and  FIG. 1B  is a perspective view illustrating how an object  30  is photographed using the image processing apparatus  20 . Referring to  FIGS. 1A and 1B , the image processing apparatus  20  of the exemplary embodiment is a tablet computer. The disclosure is not limited to the tablet computer. For example, the image processing apparatus  20  may be a smart phone or a digital camera as long as the configuration thereof is the one described below. The image processing apparatus  20  may be a terminal device, such as a notebook computer with a camera. A housing  200  of the image processing apparatus  20  includes on the rear surface thereof a camera  206 , and a flash generating device  207 . The housing  200  of the image processing apparatus  20  includes on the front surface thereof a display  204  that occupies most of the front surface. 
     As described below, when the object  30  is photographed, the video of the object  30  captured by the camera  206  is displayed on the display  204  on a real-time basis. A user may photograph the object  30  by operating an input interface (described below) mounted on the display  204  while observing the object  30  displayed on the display  204 . 
     In accordance with the exemplary embodiment, the object  30  may be a test image of a printer or a multi-function apparatus, output by an image forming apparatus. The test image is an image printed on an entire paper sheet with one or a mixture of black, cyan, magenta, and yellow colors at a given density, or may be an entire half-tone image. The test image is used to check the presence or absence of nonuniformity or banding when image data at a specific gradation value is printed out. The object that is photographed in accordance with the exemplary embodiment of the disclosure is not limited to the test image. The object  30  may be a different image. 
     If an entire image filled with the same color (solid image) is photographed as an object by the image processing apparatus  20  with the object not irradiated with light from the flash generating device  207 , a shadow may be created on the object  30  by light incoming from the outside as illustrated in  FIG. 2 . For example, nonuniformity of light reflected from the object  30 , such as luminance nonuniformity, may be caused by the shadow of the image processing apparatus  20  itself or the shadow of a hand of a photographer. 
     The object  30  may be photographed within close distance with the flash generating device  207  irradiating the object  30  with light in order to capture an image that is free from the effect of the shadow caused by light incoming from the outside. Referring to  FIG. 3 , concentric gradations about the center where light is projected appear on the object  30 . If such a problem occurs, it is difficult to check the presence or absence of nonunformity or the presence or absence of banding when the image data at a fixed gradation value is printed out. It is desirable to reduce an effect involved in image capturing. 
     The effect caused by the flash generating device  207  radiating light is desirably reduced in the image captured by the image processing apparatus  20  of the exemplary embodiment. The image is thus captured in a manner described below. 
     The configuration of the image processing apparatus  20  of the exemplary embodiment is described with reference to  FIG. 4 .  FIG. 4  illustrates the hardware configuration of the image processing apparatus  20  of the exemplary embodiment. 
     Referring to  FIG. 4 , the image processing apparatus  20  includes a controlling microprocessor  201 , a memory  202 , a storage device  203 , a display  204 , an input interface  205 , a camera  206 , and a flash generating device  207 . Each of these elements is connected to control bus  208 . 
     The controlling microprocessor  201  controls the operation of each element in the image processing apparatus  20  in accordance with a control program stored on the storage device  203 . 
     An image of the object  30  photographed by the camera  206  and a composite image generated by an image generating unit are temporarily stored on the memory  202 . 
     The storage device  203  includes a solid-state drive (SSD) or a hard disk (HDD), and stores a control program that controls each element in the image processing apparatus  20 . 
     The display  204  includes a liquid-crystal display or an organic electroluminescent (EL) display, mounted on the housing  200  of the image processing apparatus  20 , and displays information processed by a display controller described below. 
     The input interface  205  is a touch panel overlaid on the front surface of the display  204 , and serves as an input unit on which a user operating the image processing apparatus  20  inputs instructions. 
     The camera  206  is arranged on the rear surface of the housing  200  of the image processing apparatus  20 . The camera  206  captures the image of the object  30  in response to an instruction that the user inputs by operating the input interface  205 , and an instruction from a camera controller described below. The captured image is stored on the memory  202 . 
     The flash generating device  207  includes a light-emitting diode (LED) light. The flash generating device  207  serves as a light irradiation unit that irradiates the object  30  with flash light when the object  30  is photographed in response to the instruction from the camera controller. 
     The functionality of the image processing apparatus  20  of the exemplary embodiment is described with reference to  FIG. 5 .  FIG. 5  is a functional block diagram illustrating the image processing apparatus  20  of  FIG. 4 . Referring to  FIG. 5 , the image processing apparatus  20  performs the functionalities of a camera controller  211 , an image receiving unit  212 , an image generating unit  213 , and a display controller  214  when the controlling microprocessor  201  executes the control program stored on the storage device  203 . 
     The camera controller  211  controls the operations of the camera  206  and the flash generating device  207 . If the object  30  in the video captured by the camera  206  satisfies a specific condition, for example, if the object  30  is recognized in a predetermined size, the camera controller  211  adjusts focus. The camera controller  211  captures a first image by causing the flash generating device  207  to irradiate the object  30  with flash light, and immediately in succession to the capturing of the first image, captures a second image by not causing the flash generating device  207  to irradiate the object  30  with flash light, and stores the first and second images on the memory  202 . 
     The image receiving unit  212  receives the first image that has been captured with the flash generating device  207  irradiating the object  30  with flash light and the second image that has been captured with the flash generating device  207  not irradiating the object  30  with flash light. In other words, the image receiving unit  212  retrieves the first image and the second image from the memory  202 . 
     The image generating unit  213  performs projective transformation such that the first and second images retrieved by the image receiving unit  212  are corrected to be in a specified size. More specifically, when the object  30  is photographed by the camera  206  in the image processing apparatus  20 , the image of the object  30  is captured at a slight slant angle. By performing the projective transformation on the captured images, distortion is removed from the images and the images are adjusted in size. 
     The image generating unit  213  adjusts brightness of the whole second image such that brightness at a specific location in the first image retrieved and projective-transformed by the image receiving unit  212  is approximately equal to brightness at a specific location in the second image retrieved and projective-transformed by the image receiving unit  212 . The image generating unit  213  generates a composite image by replacing a pixel value of a pixel that has been affected by the irradiation of flash light from the flash generating device  207  with a pixel value of a pixel in the brightness-adjusted second image. 
     More specifically, the image generating unit  213  generates the composite image by replacing in the first image a pixel value of a pixel higher in brightness than a pixel in the second image adjusted in brightness, as a pixel that has been affected by the flash light irradiation by the flash generating device  207 , with the pixel value of the pixel in the second image adjusted in brightness. Alternatively, the image generating unit  213  generates the composite image by selecting a pixel value of the first image retrieved by the image receiving unit  212  or a pixel value of the second image retrieved by the image receiving unit  212 , whichever is lower. 
     The display controller  214  processes an image to be displayed on the display  204 . The display controller  214  performs control to display on the display  204  a video that is captured by the camera  206  when an object is photographed by the camera  206 , to display on the display  204  an image generated by the image generating unit  213 , or to display on the display  204  a user interface (UI) that allows a user to input a variety of instructions. 
     The image processing apparatus  20  of the exemplary embodiment is described with reference to  FIGS. 6, 7A and 7B , and  8 A through  8 C.  FIG. 6  is a flowchart illustrating an image composing process performed by the image processing apparatus  20  of the exemplary embodiment.  FIGS. 7A and 7B  illustrate images that have undergone projective transformation. Specifically,  FIG. 7A  illustrates the first image that is captured with the object irradiated with flash light, and  FIG. 7B  illustrates the second image that is captured with the object not irradiated with the flash light.  FIGS. 8A through 8C  illustrate the concept of the image composing process of the exemplary embodiment.  FIG. 8A  illustrates luminance of a pixel row of the image captured with the object irradiated with the flash light from the flash generating device  207  and luminance of a pixel row of the image captured with the object not irradiated with the flash light from the flash generating device  207 .  FIG. 8B  illustrates the concept of corrected luminance.  FIG. 8C  illustrates luminance of the pixel row of the composite image. 
     In step S 401 , the camera controller  211  causes the camera  206  to start operating in response to an instruction from a user. The display controller  214  displays a video captured by the camera  206  on the display  204 . The camera controller  211  determines whether the object  30  to be photographed is recognized as satisfying a predetermined condition. The condition is related to whether the object  30  is recognized as being in a predetermined size or larger. If the predetermined condition is not satisfied, an attempt to recognize the object  30  continues with the camera  206  inactive. If the object  30  that satisfies the predetermined condition is not recognized even after the time elapse of a predetermined period of time, the image composing process may end. 
     If the object  30  to be photographed is recognized as satisfying the predetermined condition, the process proceeds to step S 402 . The camera controller  211  causes the flash generating device  207  to irradiate the object  30  with flash light for image capturing. 
     In step S 403 , the camera controller  211  stores on the memory  202 , as the first image, an image that is captured with the flash generating device  207  irradiating the object  30  with the flash light. 
     In step S 404 , the camera controller  211  immediately captures the image of the object  30  with the flash generating device  207  not irradiating the object  30  with the flash light. 
     In step S 405 , the camera controller  211  stores on the memory  202 , as the second image, an image that is captured with the flash generating device  207  not irradiating the object  30  with the flash light. 
     In step S 406 , the image receiving unit  212  retrieves the first and second images from the memory  202 . The image generating unit  213  projective-transforms each of the first and second images, and corrects the projective-transformed first and second images to be equal to each other in size. During the projective transformation, distortion in the first and second image is removed. The intended image size during the projective transformation is pre-set by the user. Alternatively, during the projective transformation, the display controller  214  may request the user to specify the image size, and the user may operate the input interface  205  to specify the image size to which the images have to be scaled. 
     In step S 407 , the image generating unit  213  adjusts the brightness of the whole second image such that brightness at specific locations in the first image projective-transformed may be approximately equal to brightness at specific locations in the second image projective-transformed. The specific locations are multiple locations off the central region of each of the first image and second images projective-transformed. For example, if four imaginary lines are drawn from the center of each of the first image and second images projective-transformed to the four corners thereof, the specific locations are four points, each point at one-third length point along each imaginary line from the center of each image. The specific locations may be other multiple points in the images. The specific locations are not limited to four points, and may be a different number of points. 
     The brightness may be any index indicating a luminance value, a gradation value, lightness, or a degree of brightness of an image. In the following discussion, the brightness is luminance. According to the exemplary embodiment, the image generating unit  213  adjusts the luminance value of the whole area of the second image that has been projective-transformed such that the mean of the luminance values at the four locations in the first image projective-transformed and the mean of the luminance values at the four locations in the second image projective-transformed are approximately equal to each other, specifically within a predetermined range, or more preferably converge to the same value. Besides the mean of the luminance values, a variance of luminance or contrast may be calculated, and the second image may be adjusted such that the variance falls within a predetermined range. 
     The operation in step S 407  is described with reference to  FIGS. 7A and 7B , and  FIGS. 8A through 8C .  FIG. 7A  illustrates the state of the first image that is obtained by capturing the image of the object  30  with the object  30  irradiated with flash light and then by projective-transforming the image.  FIG. 7B  illustrates the state of the second image that is obtained by capturing an image of the object  30  with the object  30  not irradiated with flash light and then by projective-transforming the image.  FIG. 8A  illustrates luminance of the pixel row of the first image of  FIG. 7A  along line VIIIA-VIIIA and luminance of the pixel row of the second image of  FIG. 7B  along line VIIIA-VIIIA.  FIG. 8B  illustrates luminance of pixel rows of the first and second images with brightness of the second image adjusted, and  FIG. 8C  illustrates luminance of the pixel row of the composite image into which the first and second images are combined. 
     Referring to  FIGS. 7A and 7B , and  FIGS. 8A through 8C , the horizontal axis of  FIGS. 8A through 8C  illustrating the luminance of the pixel rows is an X coordinate when the image is cut in a horizontal direction, and the vertical axis represents luminance values. Referring to  FIG. 8A , luminance of the image captured with the flash generating device  207  irradiating the object with the flash light is typically higher than luminance of the image captured with the flash generating device  207  not irradiating the object with the flash light. Furthermore, the plot of the luminance of the image captured with the flash generating device  207  irradiating the object with the flash light has a hill-like shape along the horizontal axis with the peak point thereof at the central region and the slopes on both sides. Referring to  FIG. 8B , the image generating unit  213  adjusts the luminance of the whole second image projective-transformed such that luminance values at points P in the first and second images projective-transformed are equal to each other (in other words, luminance values are generally increased as illustrated in  FIG. 8B ). 
     In step S 408  of  FIG. 6 , the image generating unit  213  replaces the pixel value of a pixel that is affected by the flash light radiated by the flash generating device  207  with the pixel value of a pixel in the second image that has been adjusted in step S 407 . More specifically, the image generating unit  213  replaces the pixel value of a pixel brighter in the first image than in the second image that has been adjusted in brightness, as a pixel that has been affected by the flash light irradiated by the flash generating device  207 , with a pixel value of a pixel in the second image that has been adjusted in brightness. Alternatively, the image generating unit  213  generates a composite image by comparing the projective-transformed first image with the bright-adjusted second image on a per pixel basis, and selecting a pixel value, whichever is less bright. 
       FIG. 8C  illustrates the composite image as the resulting state. Within a range defined by specific points P, pixels in the second image adjusted in brightness are used as pixels in the composite image of  FIG. 8C . Outside the range defined by the specific points P, the pixels in the first image projective-transformed are used as pixels in the composite image of  FIG. 8C . 
     In step S 409  of  FIG. 6 , the image generating unit  213  stores the composite image generated in step S 408  on the memory  202 . The display controller  214  displays the composite image on the display  204  such that the user may observe the composite image. The image composing process then ends. 
     In the image composing process described above, in the first image projective-transformed, the pixels brighter than those in the second image adjusted in brightness are determined to be the pixels that are affected by the flash light radiated by the flash generating device  207 , and the pixel values of those pixels are thus replaced with the pixel values in the second image adjusted in brightness. The disclosure is not limited to the process. The pixel values of pixels in a region serving as a target to be replaced and of pixels surrounding the region are replaced with values that are calculated using pixel values in the first image projective-transformed and pixel values in the second pixel adjusted in brightness. In such a case, the pixel value of the pixel serving as a replacement may be obtained by combining, using SoftMinimum function, a pixel value in the first image projective-transformed and a pixel value in the second image adjusted in brightness. 
     According to the exemplary embodiment described above, the second image is captured with the object not irradiated with the flash light immediately after the first image is captured with the object irradiated with the flash light. Conversely, the first image may be captured with the object irradiated with the flash light immediately after the second image is captured with the object not irradiated with the flash light. 
     Modification of the exemplary embodiment of the disclosure is described with reference to  FIGS. 9 through 13 .  FIG. 9  illustrates the concept of an image processing system  60 A of a modification of the exemplary embodiment of the disclosure.  FIG. 10  is a functional block diagram illustrating a terminal device  20 A of the modification.  FIGS. 11A and 11B  illustrate the configuration of an image processing server  80 A of the image processing system  20 A of the modification.  FIG. 11A  illustrates the hardware configuration of the image processing server  80 A, and  FIG. 11B  is the functional block diagram of the image processing server  80 A.  FIG. 12  is a flowchart illustrating the process of the terminal device  20 A of the modification.  FIG. 13  is a flowchart illustrating the process of the image processing server  80 A of the modification. 
     In the exemplary embodiment described with reference to  FIG. 1  through  FIG. 8 , the photographing of the object  30  and the composing process of the images are performed by the single image processing apparatus  20 . In the modification described with reference to  FIG. 9  through  FIG. 13 , the photographing of the object  30  and the displaying of the composite image subsequent to image processing are performed on the terminal device  20 A, and the image processing is performed on the image processing server  80 A. 
     Referring to  FIG. 9 , the image processing system  60 A of the modification includes the terminal device  20 A and the image processing server  80 A. The terminal device  20 A and the image processing server  80 A are respectively connected to a network  70 A. In the modification, the terminal device  20 A is generally identical in hardware configuration to the image processing apparatus  20  except that the terminal device  20 A includes a communication interface (not illustrated). Elements identical to those in the image processing apparatus  20  are designated with the same reference symbols and the detailed discussion is omitted herein. 
     Referring to  FIG. 10 , a controlling microprocessor  201  in the terminal device  20 A of the modification performs a control program stored on the storage device  203 . The terminal device  20 A thus has functionalities of a camera controller  211 A, a display controller  212 A, and an image transceiver unit  213 A. The camera controller  211 A and the display controller  212 A are respectively identical in functionality to the camera controller  211  and the display controller  214  in the image processing apparatus  20  of the exemplary embodiment, and the detailed discussion thereof is omitted herein. 
     The first image is captured with the flash generating device  207  irradiating the object and the second image is captured with the flash generating device  207  not irradiating the object. The first image and the second image are stored on the memory  202  or the storage device  203 . In response to an instruction input by the user operating the input interface  205 , the image transceiver unit  213 A transmits the first image and the second image to the image processing server  80 A via the network  70 A or receives the composite image produced on the image processing server  80 A from the image processing server  80 A via the network  70 A. 
     Referring to  FIG. 11A , the image processing server  80 A of the modification includes a controlling processor  801 A, a memory  802 A, a storage device  803 A, and a communication interface  804 A, each thereof connected to a control bus  805 A. 
     The controlling processor  801 A controls the operation of each element in the image processing server  80 A in accordance with the control program stored on the storage device  803 A. The first image captured with the flash light radiating and the second image with the flash light not radiating are temporarily stored on the memory  802 A. The storage device  803 A includes a hard disk (HDD) and/or a solid-state drive (SDD), and stores the control program that controls each element in the image processing server  80 A. The communication interface  804 A controls communication that the image processing server  80 A performs with the terminal device  20 A via the network  70 A. 
     Referring to  FIG. 11B , the controlling processor  801 A in the image processing server  80 A executes the control program stored on the storage device  803 A. The image processing server  80 A has thus the functionalities of an image receiving unit  811 A, an image generating unit  812 A, and an image transmitting unit  813 A. 
     The image receiving unit  811 A receives from the terminal device  20 A the first image captured with the flash light radiating and the second image with the flash light not radiating, and temporarily stores the first and second images on the memory  802 A. 
     The image generating unit  812 A adjusts the brightness of the whole second image such that the brightness at a specific location in the first image acquired by the image receiving unit  811 A is approximately equal to the brightness at a corresponding specific location in the second image acquired by the image receiving unit  811 A. The image generating unit  812 A generates a composite image by replacing in the first image the pixel value of a pixel that is affected by the irradiation of the flash light with the pixel value of a pixel in the second image that is adjusted in brightness. The process described above remains unchanged from the process of the image generating unit  213  in the image processing apparatus  20  of the exemplary embodiment, and the detailed discussion thereof is omitted herein. 
     The image transmitting unit  813 A transmits to the terminal device  20 A the composite image generated by the image generating unit  812 A via the communication interface  804 A and the network  70 A. 
     The process of the image processing system  60 A of the modification is described below. The process of the terminal device  20 A is described first with reference to  FIG. 12 . In step S 901  of  FIG. 12 , the camera controller  211 A causes the camera  206  to start operating in response to an instruction that is input by the user operating the terminal device  20 A. The terminal device  20 A photographs the object by causing the flash generating device  207  to irradiate the object with the flash light, and temporarily stores the captured image as the first image on the memory  202 . 
     In step S 902 , the image transceiver unit  213 A transmits the first image to the image processing server  80 A via the network  70 A. 
     In step S 903 , the camera controller  211  photographs the object with the flash generating device  207  not irradiating the object, and stores the captured image as the second image on the memory  202 . 
     In step S 904 , the image transceiver unit  213 A transmits the second image to the image processing server  80 A via the network  70 A. In the modification of the exemplary embodiment, the first image and the second image are transmitted to the image processing server  80 A each time each of the first and second images is captured. Alternatively, the first and second images, after being captured, may be together transmitted to the image processing server  80 A. 
     Referring to  FIG. 13 , the composing process of the images is performed on the image processing server  80 A. In step S 905 , the image transceiver unit  213 A receives the composite image from the image processing server  80 A, and stores the composite image on the memory  202 . 
     In step S 906 , the display controller  212 A displays on the display  204  the composite image received in step S 905  such that the user may view the composite image. The process thus ends. 
     The process of the image processing server  80 A is described with reference to  FIG. 13 . In step S 1001  of  FIG. 13 , the image receiving unit  811 A in the image processing server  80 A receives the first image and the second image from the terminal device  20 A. The first image and the second image may be received together at the same time or separately with a time difference therebetween. The first image and the second image are temporarily stored on the memory  802 A. 
     In step S 1002 , the image generating unit  812 A projective-transforms each of the first and second images such that the two images are equal in size. The image size serving as a target of the projective transformation may be preset by the user, and the information on the image size may be received together with the first and second images. Alternatively, the terminal device  20 A may be requested to specify the image size, and the user may specify the image size by operating the input interface  205  in the terminal device  20 A. The information on the specified image size may be transmitted to the image processing server  80 A. 
     In step S 1003 , the image generating unit  812 A adjusts the brightness of the whole second image such that the brightness at a specific location in the first image projective-transformed is approximately equal to the brightness at a specific location in the second image projective-transformed. The operation is generally identical to the operation that the image generating unit  213  in the image processing apparatus  20  performs in step S 407  of  FIG. 6 , and the detailed discussion thereof is omitted herein. 
     In step S 1004 , the image generating unit  812 A generates a composite image by replacing in the first image projective-transformed the pixel value of a pixel that is affected by the irradiation of the flash light with the pixel value of a pixel in the second image that is adjusted in brightness in step S 1003 . The operation is generally identical to the operation that the image generating unit  213  in the image processing apparatus  20  of the exemplary embodiment performs in step S 408  of  FIG. 6 , and the detailed discussion thereof is omitted herein. 
     In step S 1005 , the image transmitting unit  813 A transmits the composite image generated in step S 1004  to the terminal device  20 A via the communication interface  804 A and the network  70 A. The process thus ends. 
     In the modification of the exemplary embodiment, the terminal device  20 A captures the first image and the second image, and successively transmits the first image and the second image to generate the composite image. The disclosure is not limited to this method. The first image and the second image may be first stored on the storage device  203  in the terminal device  20 A, and the image processing server  80 A may later retrieve the first and second images, and generate the composite image. 
     The foregoing description of the exemplary embodiments of the present disclosure has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure to the precise forms disclosed. Obviously, many modifications and variations will be apparent to practitioners skilled in the art. The embodiments was chosen and described in order to best explain the principles of the disclosure and its practical applications, thereby enabling others skilled in the art to understand the disclosure for various embodiments and with the various modifications as are suited to the particular use contemplated. It is intended that the scope of the disclosure be defined by the following claims and their equivalents.