JP2013223048A - Image processing apparatus and method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow for shading correction of plural color patches included in imaging data obtained by photographing a color chart once.SOLUTION: A data input and output unit 101 obtains the imaging data obtained by photographing a color chart which includes both plural color patches of different colors and plural correction patches. A background data generation unit 104 generates background data from image data on the correction patches included in the imaging data. An image data correction unit 105 performs the shading correction of the imaging data using the background data.

Description

  The present invention relates to image processing for obtaining color characteristics of an image output device.

  Accompanying the widespread use of personal computers, it is easier to acquire images using image input devices such as digital cameras and color scanners, and display the images on image display devices such as LCDs and print them using image output devices such as printers. It was. Under such circumstances, color management technology (hereinafter referred to as CMS) for managing the reproduction colors of image input devices, image display devices, and image output devices has become essential.

  In order to manage the color reproduction of each device, it is necessary to obtain in advance the color reproduction characteristics of the device under observation conditions. The color reproduction characteristic represents a relationship between a color signal (for example, sRGB value) input to the device and a color (for example, CIE tristimulus value XYZ, hereinafter, XYZ value) represented by the device. In general, the XYZ values of a device are obtained by measuring one by one with a contact-type measuring instrument that measures a number of color charts displayed or output by the device in contact with the device.

As a method for acquiring the XYZ values of the device more simply, there is a method using an imaging device such as a digital camera. When using an imaging device, for example, a color chart output by a device to be measured is photographed, and the RGB values of each color chart represented by the imaging data are converted into XYZ values. FIG. 1 shows an example of a color chart. In the color chart, for example, color charts for a total of 9 ³ = 729 colors obtained by equally slicing RGB values into 9 slices are arranged.

  According to the method of acquiring the XYZ values of the device using the imaging apparatus, the XYZ values of a plurality of color charts arranged on the color chart as shown in FIG. 1 can be acquired by one shooting. However, in shooting using a non-contact imaging device under a general lighting environment, there is uneven light (hereinafter referred to as uneven illumination) that illuminates the color chart during shooting. The color chart also has color unevenness called “in-plane unevenness” that depends on the device that outputs it. In order to reduce the influence of these unevenness (hereinafter, shading), it is necessary to perform shading correction on the image data of the color chart.

  Patent Document 1 photographs a chart for shading correction (a chart having a uniform white surface, hereinafter referred to as a correction chart) under the same illumination environment as when photographing a color chart. Then, a shading correction coefficient is calculated from the imaging data of the correction chart, and the imaging data of the color chart is subjected to shading correction using the coefficient.

  According to the method of Patent Document 1, accurate correction is expected even for complex shading. However, at least twice photographing and two imaging data are required for shading correction. Furthermore, it is premised that the geometric conditions between the light source and the chart at the time of the two shootings are the same, and a mechanism for absorbing the difference in the geometric conditions is required by strict setting of the geometric conditions such as alignment. .

  Patent Document 2 discloses a technique for detecting a representative point from a frame (margin) around a gray scale chart, calculating a correction coefficient from imaging data of the detected point, and performing shading correction in the horizontal direction and the vertical direction. Disclose. According to the technique disclosed in Patent Document 2, when uniform shading occurs in the horizontal direction or the vertical direction over the entire area of the color chart, a highly accurate correction result can be obtained without taking a correction chart or the like. You can expect. However, such shading occurs rarely and often does not fall under such a case. For example, complex shading in which non-uniform shading occurs in the horizontal direction and / or vertical direction over the entire area of the color chart cannot be corrected with a correction coefficient obtained from a slight margin around the chart.

JP 2007-081580 A JP 2003-234922 A

  An object of the present invention is to enable shading correction using a plurality of color patches included in imaging data obtained by photographing a color chart once.

  The present invention has the following configuration as one means for achieving the above object.

  The image processing according to the present invention inputs imaging data obtained by photographing a color chart in which a plurality of color patches having different colors and a plurality of correction patches are mixed, and images of the plurality of correction patches included in the imaging data. Background data is generated from data, and the imaging data is subjected to shading correction using the background data.

  According to the present invention, it is possible to perform shading correction using a plurality of color patches included in imaging data obtained by photographing a color chart once. For example, even when non-uniform complex shading occurs in the horizontal direction and / or the vertical direction throughout the entire color chart, shading correction using a plurality of color patches can be performed.

The figure which shows an example of a color chart. 1 is a block diagram illustrating a configuration example of an image processing apparatus according to an embodiment. The flowchart explaining the process which a control part performs. The figure which shows an example of UI for color chart preparation, and UI for shading correction | amendment. The figure which shows an example of color patch information. The figure which shows an example of a color chart. The figure which shows an example of imaging data and background data. The flowchart explaining the process of a background data generation part. FIG. 3 is a block diagram illustrating a configuration example of an image processing apparatus according to a second embodiment. The flowchart explaining the process which a control part performs. The figure which shows the example which has arrange | positioned the color chart in several different positions. 10 is a diagram illustrating an example of a UI for creating a color chart according to Embodiment 3. FIG. The figure which shows an example of the arrangement pattern of the correction | amendment patch registered into each button of an arrangement pattern part.

  Hereinafter, image processing according to an embodiment of the present invention will be described in detail with reference to the drawings.

[Device configuration]
A block diagram of FIG. 2 shows a configuration example of the image processing apparatus of the embodiment.

  An output device 12 such as a liquid crystal monitor (LCD) and an imaging device 13 such as a digital camera are connected to the image processing device 11 via a predetermined interface. The output device 12 displays (outputs) the color chart, and the imaging device 13 captures the color chart. The image processing device 11 performs shading correction using the color chart image data acquired from the image capturing device 13. Here, an example in which the output device 12 is a monitor will be described, but other output devices such as a printer may be used.

  Note that “shading” in the present embodiment is a generic term for so-called “in-plane unevenness” that depends on the unevenness of light that illuminates the color chart (hereinafter referred to as unevenness of illumination) and the device that outputs the color chart, as described above. . That is, the image processing apparatus 11 performs shading correction on the image data of the color chart in order to reduce the influence of shading.

  The data input / output unit 101 is a serial bus interface such as USB (Universal Serial Bus) or IEEE1394 that connects the image processing apparatus 11 and input / output devices such as the output apparatus 12 and the imaging apparatus 13. The chart generation unit 102 generates chart data of the color chart formed by the output device 12, and supplies the generated chart data to the output device 12 via the data input / output unit 101. Note that the chart data may be acquired from the storage unit 106 or a media or server device (not shown).

  The instruction input unit 103 displays a user interface (UI) on a monitor (not shown), and receives an instruction input from a user who operates a keyboard, a mouse, a touch panel, etc. (not shown). The background data generation unit 104 generates background data from the color chart image data captured by the image capturing device 13. The image data correction unit 105 performs shading correction on the imaging data of the color chart captured by the imaging device 13, and stores the correction data in a predetermined area of the storage unit 106. The control unit 107 controls the operation of the above configuration of the image processing apparatus 11.

[processing]
Processing executed by the control unit 107 will be described with reference to the flowchart of FIG.

  When the acquisition of device XYZ values is instructed by the user, the control unit 107 controls the instruction input unit 103 to display a color chart creation UI and acquire parameters for color chart creation (S11).

  FIG. 4 shows an example of a UI for creating a color chart. The user designates a file in which color patch information of the color chart to be output to the output device 12 is recorded in the color patch information column 201 or presses a browse button to select the file. FIG. 5 shows an example of color patch information. The color patch information is a data file in which the number of color patches and the RGB value for each color patch corresponding to the patch number are described.

  Next, the user designates a storage destination of the imaging data from the imaging data column 202 or presses a reference button to select the storage destination. Although not shown in the figure, a chart output destination field is provided so that the chart data can be reused by specifying the storage destination of the chart data generated by the user or selecting the storage destination. May be. In addition, a preset storage destination may be selected. When the setting of the color patch information and the storage destination is completed, the user presses the chart creation / output button 203.

  When the chart creation / output button 203 is pressed (S12), the control unit 107 controls the chart generation unit 102 to generate chart data based on the color patch information recorded in the file designated by the user (S13). . Further, when the chart data storage destination is designated, the generated chart data is stored in the storage destination.

  FIG. 6 shows an example of a color chart. In the color chart generated by the chart generation unit 102, color patches having different colors and shading correction patches (hereinafter, correction patches) are mixed. In the example of FIG. 6, color patches and correction patches are alternately arranged, and at least two correction patches are arranged around the color patches. The correction patch is a single color patch having the same color as the background color (white in the example of FIG. 6).

  Next, the control unit 107 outputs the chart data stored in the storage unit 106 to the output device 12 via the data input / output unit 101 (S14). The output device 12 displays a color chart corresponding to the input chart data. The control unit 107 controls the imaging device 13 via the data input / output unit 101, captures the color chart displayed by the output device 12, acquires the imaging data, and stores the acquired imaging data in the designated storage destination. Store (S15).

  Note that the user may directly photograph the color chart by operating the imaging device 13, or the color chart can be photographed by operating the UI provided by the instruction input unit 103. Further, the imaging data acquired from the imaging device 13 is image data converted from RAW data into, for example, the TIFF format by development processing such as demosaicing in the imaging device 13, and the RGB channel values (RGB) for each pixel. Value). Needless to say, when photographing a color chart, the color chart is in an observation environment where it is desired to measure the color reproduction characteristics of the output device.

  Thereafter, when a shading correction is instructed by the user, the control unit 107 controls the instruction input unit 103 to display a shading correction UI and acquire a shading correction parameter (S16).

  FIG. 4 shows an example of a shading correction UI. Although FIG. 4 shows an example in which a UI for color chart creation and a UI for shading correction are juxtaposed, UIs independent of each other may be used. The user designates the image data of the color chart in the image data field 204 or selects the data by pressing the reference button. Next, the user designates a storage destination of the imaging data after the shading correction by using the shading correction result field 205 or presses a reference button to select the storage destination. When the setting of the storage destination of the image data before correction and the image data after correction is completed, the user presses the correction processing execution button 206.

  When the correction process execution button 206 is pressed (S17), the control unit 107 controls the background data generation unit 104 to generate background data from the image data of the color chart specified by the user, as will be described in detail later (S17). S18). The background data is created based on the color of the correction patch of the color chart. FIG. 7 shows an example of imaging data and background data. FIG. 7A shows image data of a color chart, and FIG. 7B shows background data generated from the correction patch color of the image data.

  The background data represents the degree of shading of the output device 12, and is image data used to correct this shading. Specifically, the image data is generated based on the image data of the image excluding the color patch in the color chart.

Next, the control unit 107 controls the image data correction unit 105 to perform shading correction of the color chart imaging data based on the background data (S19), and stores the corrected imaging data in the designated storage destination (S19). S20). The image data correction unit 105 calculates a corrected RGB value using the following equation for each RGB value of each pixel of the imaging data.
Ry = Rx × Rmax / Rw
Gy = Gx × Gmax / Gw (1)
By = Bx × Bmax / Bw
Here, Rx, Gx, Bx are the pixel values of the imaging data (before correction)
Ry, Gy, By are pixel values after correction.
Rw, Gw, and Bw are the values of the background data pixels at the same position as the pixels of the imaging data,
Rmax, Gmax, and Bmax are the maximum values on the background data.

Note that although the example using the maximum values Rmax, Gmax, and Bmax is shown in Equation (1), the average values Rave, Gave, and Bave may be used as in the following equations.
Ry = Rx × Rave / Rw
Gy = Gx × Gave / Gw… (2)
By = Bx × Bave / Bw

  A shading correction coefficient is used for shading correction of the color patch. The shading correction coefficient corresponds to Xmax / Xw in equation (1) or Xave / Xw in equation (2) (X is R, G, or B). Therefore, it is possible to calculate a correction coefficient obtained by dividing the interpolation value Xw by Xmax or Xave without generating background data in step S18, and perform shading correction using equation (1) or equation (2) in step S19. Good. At that time, the maximum value of the correction patch is used for Xmax, and the average value of the correction patches is used for Xave.

Background Data Generation Unit The process (S18) of the background data generation unit 104 will be described with reference to the flowchart of FIG.

  The background data generation unit 104 acquires information indicating the interpolation target area in the imaging data, that is, the number of color patches, the number of correction patches, and position information of these patches (S501). In the case of a color chart as shown in FIG. 6, since the background and correction patches other than the color patch are white, information indicating the interpolation target region is acquired by binarization processing using a predetermined threshold. It is possible.

  Next, the background data generation unit 104 determines the position of a patch to be interpolated (hereinafter referred to as an interpolation patch) (S502). For example, scanning is performed in the raster order from the upper right to the lower left of the image represented by the imaging data, and the position where the color patch other than the correction patch exists is determined as the position of the interpolation patch.

  Next, the background data generation unit 104 determines a pixel value (hereinafter, an interpolation value) for interpolating the interpolation patch (S503). In the case of the color chart shown in FIG. 6, the average values (hereinafter referred to as RGB average values) of the R value, G value, and B value of at least two and up to four correction patches located at the top, bottom, left and right of the interpolation patch are obtained Then, an RGB value obtained by averaging the RGB average values again is used as an interpolation value. The method for determining the interpolation value is not limited to this, and may be a different form.

  Next, the background data generation unit 104 replaces the pixel value of the interpolation patch with the determined interpolation value (S504). Then, it is determined whether or not the processing of steps S502 to S504 has been performed for the number of color patches (S505), and if there are unfinished color patches, the processing returns to step S502. When all the interpolation patches have been processed, the background data generation process is terminated.

  In this way, even when non-uniform complex shading occurs horizontally and / or vertically in the entire area of the color chart, a plurality of color patches (color charts) included in the image data obtained by photographing the color chart once. ) Shading correction becomes possible.

  The image processing according to the second embodiment of the present invention will be described below. Note that the same reference numerals in the second embodiment denote the same parts as in the first embodiment, and a detailed description thereof will be omitted.

  In the first embodiment, the example in which the shading correction is performed using the background data obtained by interpolating the pixel values of the interpolation patch from the correction patches around the interpolation patch has been described. However, when the output device is a monitor or the like, there is a possibility that local shading that falls within the patch, such as missing pixels, may occur. If there is such local shading, the pixel value of the interpolation patch cannot be accurately interpolated, resulting in an inaccurate shading correction result.

[Device configuration]
A block diagram of FIG. 9 shows a configuration example of the image processing apparatus according to the second embodiment. The image processing apparatus 11 according to the second embodiment includes a pass / fail determination unit 111 and a colorimetric value conversion unit 112 in addition to the configuration of the first embodiment. The pass / fail determination unit 111 determines whether or not the shading correction is accurately performed for each color patch. The colorimetric value conversion unit 112 converts the RGB value of each color patch into an XYZ value.

[processing]
Processing executed by the control unit 107 will be described with reference to the flowchart of FIG.

  The processing from step S11 to S18 is almost the same as in the first embodiment, but the processing for outputting the chart data stored in the storage unit 106 to the output device 12 is different from that in step S14 in the first embodiment. That is, when outputting the chart data stored in the storage unit 106 to the output device 12 via the data input / output unit 101, the control unit 107 outputs the chart data arranged at a plurality of different positions in the color chart. (S24).

  FIG. 11 shows an example in which color charts are arranged at a plurality of different positions. Note that the number and position of the color charts may be obtained from, for example, a UI for the user to set the number and arrangement of the color charts by the instruction input unit 103 in step S11. In step S15, imaging data obtained by collectively shooting a plurality of color charts arranged at a plurality of positions is input.

  The processing of steps S16 to S18 is executed for each color chart by the number of color charts included in the image represented by the imaging data.

  Next, the control unit 107 controls the image data correction unit 105 to perform shading correction of the imaging data of each color chart based on the background data, and stores the corrected imaging data in the storage unit 106 (S29).

  Next, the control unit 107 acquires average values (hereinafter referred to as RGB average values) of the R value, G value, and B value of each color patch from the imaging data after shading correction, and supplies the average values to the pass / fail determination unit 111 ( S30). For example, in the case of imaging data acquired from the same color chart arranged at four locations and subjected to shading correction, there are four patches with the same arrangement (hereinafter referred to as the same color patch) in the color chart, and RGB of the same color patch Four average values are obtained.

  Next, the control unit 107 excludes an inappropriate RGB average value from the four RGB average values acquired for each same color patch by the pass / fail determination unit 111, and determines an RGB average value to be converted into an XYZ value (S31). .

  The RGB average value of the same color patch formed by the same input signal should be the same value after shading correction. However, when local shading occurs, accurate shading correction cannot be performed, and the RGB average value may be different. In order to exclude an inappropriate RGB average value, for example, an RGB average value whose sum of RGB values indicates the maximum and minimum values may be removed, and the remaining RGB average value may be converted into an XYZ value. When shooting color charts arranged at three locations, if the inappropriate RGB average value is excluded, the remaining RGB average value is one, but when shooting color charts arranged at four or more locations, it is inappropriate. Excluding the RGB average value leaves two or more RGB average values. When two or more RGB average values remain, a value obtained by averaging the RGB average values again is converted into an XYZ value.

  In addition, the method of excluding the influence of an inappropriate RGB average value is not limited to the above, a method of averaging a plurality of RGB average values again, or a method of using an RGB average value in which the sum of RGB values indicates a median value Etc.

Next, the control unit 107 calculates an XYZ value from the RGB average value by the colorimetric value conversion unit 112 (S32). For example, one of the following formulas is used for conversion from RGB to XYZ.
┌ ┐ ┌ ┐
│Xp│ │Rp│
│Yp│ = M1│Gp│… (3)
│Zp│ │Bp│
└ ┘ └ ┘
┌ ┐
｜ Rp ｜
┌ ┐ ｜ Gp ｜
｜ Xp ｜ ｜ Bp ｜
｜ Yp ｜ = M2 ｜ Rp ・ Rp ｜ (4)
｜ Zp ｜ ｜ Gp ・ Gp ｜
└ ┘ ｜ Bp ・ Bp ｜
｜ 1 ｜
└ ┘
┌ ┐
｜ Rp ｜
｜ Gp ｜
┌ ┐ ｜ Bp ｜
｜ Xp ｜ ｜ Rp ・ Rp ｜
｜ Yp ｜ = M3 ｜ Gp ・ Gp ｜… (5)
｜ Zp ｜ ｜ Bp ・ Bp ｜
└ ┘ ｜ Rp ・ Gp ｜
｜ Rp ・ Bp ｜
｜ Gp ・ Bp ｜
｜ 1 ｜
└ ┘
Where (Rp, Gp, Bp) is the RGB average value of patch p,
(Xp, Yp, Zp) is the XYZ tristimulus value of patch p,
M1 is a 3x3 matrix that converts RGB values into colorimetric values.
M2 is a 3x7 matrix that converts RGB values to colorimetric values.
M3 is a 3x10 matrix that converts RGB values into colorimetric values.

  Note that the conversion matrices M1 to M3 in the equations (3) to (5) are stored in advance in the storage unit 106 or the like. Further, the order of the matrix need not be limited to the above three types, and may be a matrix of 3 × 20, for example. Furthermore, the colorimetric value converted from the RGB value is not limited to the XYZ value, and may be, for example, a CIELab value or a CIECAM02 Jab value.

  Next, the control unit 107 stores the XYZ values of each color patch in the storage destination specified as the colorimetric data of the color chart (S33). Note that RGB values before conversion to XYZ values may be stored in the save destination together with the XYZ values, or RGB values before conversion (RGB values excluding the influence of inappropriate RGB average values) are saved. It may be stored first.

  In this manner, imaging data obtained by photographing a plurality of color charts formed at different positions is acquired, and the influence of local shading is excluded using the imaging data of the plurality of color charts subjected to shading correction. Therefore, one image data or colorimetric data excluding the influence of local shading can be obtained.

  Hereinafter, image processing according to the third embodiment of the present invention will be described. Note that the same reference numerals in the third embodiment denote the same parts as in the first and second embodiments, and a detailed description thereof will be omitted.

  Although examples of color charts are shown in FIGS. 6 and 11, the color chart is not limited to them. In the third embodiment, an example in which the user creates a color chart used for shading correction using the UI will be described. In the third embodiment, a chart creation method using a UI will be described, but other processes are the same as those in the first and second embodiments.

  FIG. 12 shows an example of a UI for creating a color chart according to the third embodiment. A display unit 1006 shown in FIG. 12 is a window for visually confirming a color chart to be formed in advance. That is, the color chart displayed on the display unit 1006 is sequentially updated as the input parameters are changed until the chart creation button 1005 is pressed.

  The reference field 1001 is used to specify a file when referring to a file in which color patch information is recorded. The format of the file in which the color patch information is recorded is as described with reference to FIG. The input unit 1002 is used to specify the color of the correction patch. That is, the user inputs RGB values to the input unit 1002 and specifies the color of the correction patch.

  The ratio adjustment field 1003 is used to adjust the ratio of correction patches to the number of color patches. That is, when the slider of the ratio adjustment field 1003 is set to “1.0”, for example, the same number of correction patches as the color patches are arranged. When high accuracy of shading correction is required, the user moves the slider closer to “1.0” and increases the number of correction patches. In addition, when the size of the color chart formed by the output device is small, if there are many correction patches, the patch size becomes small, and there is a possibility that the color cannot be detected accurately. In that case, the user moves the slider closer to “0.3” and suppresses the number of correction patches. FIG. 11 shows an example in which the range of the ratio that can be set by the slider is “0.3” to “1.0”. However, the range is not limited to this range, and a sufficient number of correction patches for shading correction can be obtained. An arbitrary ratio may be set within the range.

  Similarly, in the above-described embodiment, an example in which at least two correction patches are arranged adjacent to the color patch and arranged at the periphery of the color chart and four at the center is shown. However, the arrangement condition of the correction patch may be changed according to the accuracy of the shading correction requested by the user. For example, when high accuracy is required, the correction patch placement conditions are the same as in the above embodiment, and when high accuracy is not required, at least one correction patch within the range of vertical and horizontal P × Q patches centering on the color patch. You may make it the arrangement conditions which arrange | position a patch. If there is no correction patch adjacent to the color patch, the RGB average value of the correction patch at the shortest position from the interpolation patch is set to the RGB average value of the interpolation patch.

  In the UI shown in FIG. 12, the correction patch arrangement pattern can be registered in each button of the arrangement pattern column 1004. FIG. 13 shows an example of the correction patch arrangement pattern registered in each button of the arrangement pattern column 1004. FIG. 13 (e) shows an arrangement pattern in which color patches and correction patches as used in the above embodiment are alternately arranged. An arrangement pattern as shown in FIGS. 13A, 13B, 13C, and 13D is also possible. In addition, the arrangement pattern shown in FIGS. 13 (a) (b) (c) (d) (e) has a regular period (periodicity), but may be a random arrangement pattern as shown in FIG. 13 (f). . Further, it is sufficient that the correction patches are dispersed to such an extent that shading can be expressed.

  When the user presses the chart creation button 1005 after setting each parameter, chart data of a color chart corresponding to the parameter set by the user is created.

  Furthermore, for example, the user can specify the position where the correction patch is arranged by specifying the position on the color chart displayed on the display unit 1006, and can set the margin distance between the color patches. An input field may be provided in the UI.

[Modification]
Device Configuration In the above embodiment, the image processing device 11 and the imaging device 13 have been described as separate housings. However, the image processing device 11 may be incorporated in the imaging device 13 so as to be included in the imaging device 13. In addition, the generation of the chart at that time may be performed according to the shooting mode of the imaging device 13 without using the UI.

Chart generation unit In the above embodiment, an example in which one color is set for the correction patch has been described. However, a plurality of colors may be set for the correction patch. For example, white and black are set for the correction patch, and two types of background data of all white and all black are created as background data. Then, Rw, Gw, Bw, Rmax, Gmax, and Bmax in Equation (1) are all black background data when the luminance value of the color patch to be corrected is low, and all white background data when the luminance value is high. RGB value of is used. This makes it possible to perform highly accurate shading correction that takes into account the difference in illumination unevenness depending on the color.

  In the above-described embodiment, an example in which the chart data is generated by the chart generation unit 102 has been described. However, the chart data stored in the storage unit 106, the storage device, the medium, or the server may be used in a form that uses pre-created chart data. Good.

Background Data Generation Unit Background data generation by the background data generation unit 104 is not limited to the above method. For example, for each interpolation patch, a correction patch having a similar peripheral luminance pattern may be searched from the entire area of the image, and interpolation may be performed using the pixel value of the most similar correction patch. The background data is used to obtain a correction coefficient. For example, Rmax / Rw, Gmax / Gw, and Bmax / Bw in Equation (1) are applicable, and an image format such as TIFF is not necessarily used to obtain the correction coefficient. There is no need to keep as.

Image Data Correction Unit Shading correction by the image data correction unit 105 is not limited to the equations (1) and (2). For example, the RGB value of the background data at the position of the color patch may be subtracted from the RGB value of each color patch of the imaging data.

[Other Examples]
The present invention can also be realized by executing the following processing. That is, software (program) that realizes the functions of the above-described embodiments is supplied to a system or apparatus via a network or various storage media, and a computer (or CPU, MPU, etc.) of the system or apparatus reads the program. It is a process to be executed.

Claims (12)

Input means for inputting imaging data obtained by photographing a color chart in which a plurality of color patches having different colors and a plurality of correction patches are mixed;
Background data generating means for generating background data from image data of the plurality of correction patches included in the imaging data;
An image processing apparatus comprising: correction means for correcting shading of the imaged data using the background data.   2. The image processing apparatus according to claim 1, wherein the plurality of color patches and the plurality of correction patches are alternately arranged on the color chart.   2. The image processing apparatus according to claim 1, wherein the plurality of color patches and the plurality of correction patches are randomly arranged on the color chart.   2. The apparatus according to claim 1, further comprising chart data generation means for generating chart data for forming the color chart and outputting the chart data to an output device for forming the color chart. 4. The image processing device according to any one of 3. And a means for inputting a ratio between the number of the color patches included in the color chart and the number of the correction patches.
5. The image processing apparatus according to claim 4, wherein the chart data generation unit generates chart data of a color chart in which the color patch and the correction patch are arranged according to the ratio.   5. The image processing apparatus according to claim 4, wherein the chart data generation unit outputs chart data that causes the output apparatus to form an image in which the color chart is arranged at each of a plurality of different positions. The input means inputs imaging data obtained by collectively shooting the plurality of color charts, the background data generating means generates the background data for each of the plurality of color charts, and the correcting means is for each of the plurality of color charts. The shading correction is performed on the image data of
7. The image processing apparatus according to claim 6, further comprising means for generating one imaging data from the image data after the shading correction of the plurality of color charts.   8. The image processing apparatus according to claim 1, wherein the plurality of correction patches have a single color.   The background data generation means interpolates the color of the correction patch when the correction patch is arranged at the position where the color patch is arranged from the color of the correction patch around the position, and 9. The image processing apparatus according to claim 1, wherein background image data is generated.   10. The image processing apparatus according to claim 1, wherein the input unit inputs the imaging data from an imaging apparatus. An image processing method of an image processing apparatus having input means, background data generation means, and correction means,
The input means inputs imaging data obtained by photographing a color chart in which a plurality of color patches having different colors and a plurality of correction patches are mixed,
The background data generating means generates background data from image data of the plurality of correction patches included in the imaging data,
An image processing method, wherein the correction means performs shading correction on the imaging data using the background data.   11. A program for causing a computer to function as each unit of the image processing apparatus according to claim 1.