JP2016054405A - Color processing device and method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To create a color conversion profile which is faithful to a human perception and can equalize a perceptive interpolation error.SOLUTION: A measurement value acquisition portion 102 acquires a data set including measurement values of color that an image output apparatus outputs. A correction matrix generation portion 104 generates a second correction parameter for equally rearranging perceptually a first matrix that equally divides a reference color space, using a first correction parameter that converts a color value in the reference color space into a color value in an equal color perception space. A color reproduction area calculation portion 105 converts the measurement values that the data set includes using the first correction parameter so as to calculate a color value indicating the color reproduction area in the equal color perception space of the image output apparatus. A multi-dimensional LUT creation portion 106 creates a table for converting the color value in the reference color space into a signal value depending on the image output apparatus, on the basis of the second correction parameter and the color reproduction area.SELECTED DRAWING: Figure 3

Description

  The present invention relates to color processing for creating a color conversion profile.

  For color matching between various image input / output devices, a color profile such as an ICC profile (see Non-Patent Document 1) is used. The ICC profile has an AtoB tag that is a look-up table (LUT) that converts device-dependent signal values into device-independent PCS values, and a BtoA tag that is an LUT that converts PCS values into device-dependent signal values. Note that device-dependent signal values are generally RGB values and CMYK values, and device-independent signal values are CIEL * a * b * values.PCS is an abbreviation for profile connection space. is there. An AtoB tag and a BtoA tag are configured by a combination of a matrix, a one-dimensional LUT, and a multidimensional LUT.

  To create an AtoB tag that converts device-dependent signal values to PCS values, a color chart with a known signal value displayed on a monitor or printed by a printer is measured by a colorimeter, and the PCS corresponding to the signal value is displayed. Get the value. Then, by interpolating the acquired PCS value, an AtoB tag for converting the device-dependent signal value to the PCS value is created in the entire signal value.

  On the other hand, to create a BtoA tag that converts a PCS value to a device-dependent signal value, a grid point is defined on the PCS. Then, BtoA tags are created by obtaining device-dependent signal values corresponding to the PCS values of those lattice points by interpolation calculation. The PCS grid points include colors outside the color range that can be reproduced by the device (hereinafter referred to as the color reproduction range). In order to keep all the grid points within the color reproduction range of the device, the PCS is subjected to color space compression. Is done.

  The AtoB tag and BtoA tag of the image input / output device thus created are referred to by the color matching module (CMM). The CMM performs color conversion of image data with reference to the AtoB tag and the BtoA tag, thereby realizing color matching between input / output devices.

FIG. 1 shows an example of a multidimensional LUT included in a BtoA tag. A multi-dimensional LUT included in a BtoA tag is generally a coordinate (color value) of each grid point of a grid (hereinafter referred to as a uniform grid) obtained by equally dividing the numerical range of each axis of the PCS, and a device corresponding to these grid points. It has a structure in which dependent signal values are stored. In Non-Patent Document 1, for example, in the case of a profile of L * a * b * values, the numerical range of PCS is defined as follows.
0 ≦ L * ≦ 100,
-128 ≦ a * ≦ 127,
-128 ≦ b * ≦ 127.

The number of divisions of the numerical range of each axis can be selected from 8, 16, 32, etc. depending on the accuracy. FIG. 1 shows an LUT of 17 ³ = 4913 lattice points obtained by dividing the numerical range of each axis into 16 parts. When input data (L * a * b * values) located between grid points is input, the CMM refers to the output data (device-dependent signal values) of the grid points that surround the input data. Interpolate the output data corresponding to. Therefore, as the number of grid points is larger and the distance between the grid points is shorter, the error due to the interpolation calculation (hereinafter, interpolation error) can be reduced.

  The CIEL * a * b * space used as PCS is not necessarily a color space equivalent to human perception. For this reason, when a multidimensional LUT in which the numerical range of each axis of the PCS is evenly divided is used, there is a problem that the interpolation error is perceptually nonuniform depending on the region. For example, the interpolation error is perceived to be large in the low saturation region and small in the high saturation region. In other words, even if the numerical interpolation error is equalized, the perceptual interpolation error varies depending on the color gamut and is not uniform.

  Patent Document 1 discloses a method for solving the above problem. According to Patent Document 1, by converting the a * value and b * value of PCS using an S-shaped function, the lattice point density of the LUT is made denser in the vicinity of the gray axis and coarsened away from the gray axis. To improve the accuracy of interpolation calculations.

  However, the distortion to the perception of the CIEL * a * b * space is complex, and even with the simple S-shaped transformation in the saturation direction shown in Patent Document 1, the perceptual interpolation error uniformity cannot be obtained. The interpolation error in cannot be perceptually equalized. Furthermore, the technology of Patent Document 1 uses CIEL * a * b to perform color space compression on the CIEL * a * b * space when mapping grid points outside the device's color reproduction range to the device's color reproduction range. * Visually faithful color reproduction is often not obtained due to distortion effects on spatial perception.

Japanese Patent No. 4250863 (JP 2002-152530) JP 2013-021679 A

International Color Consortium, Specification ICC. 1: 2004-10, (Profile Version 4.2.0.0) D. L. MacAdam "Visual sensitibities to color differences in daylight" Journal of the Optical Society of America, Vol. 32, No. 5, pp. 247-274, May 1942

  An object of the present invention is to create a color conversion profile that is faithful to human perception and can equalize perceptual interpolation errors.

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

  The color processing according to the present invention uses a first correction parameter that obtains a data set that includes measurement values of colors output from an image output device and converts color values in a reference color space into color values in a uniform color perception space. Generating a second correction parameter for rearranging the first grid that equally divides the reference color space in a perceptual manner, and converting the measurement value included in the data set using the first correction parameter. A color value indicating a color gamut in the uniform color perception space of the image output device is calculated, and the color value of the reference color space is calculated based on the second correction parameter and the color gamut. Create a table to convert to signal values that depend on.

  According to the present invention, it is possible to create a color conversion profile that is faithful to human perception and can equalize perceptual interpolation errors.

The figure which shows an example of the multidimensional LUT contained in a BtoA tag. 1 is a block diagram illustrating a configuration example of an information processing apparatus that functions as a color processing apparatus according to an embodiment. FIG. 2 is a block diagram illustrating a processing configuration example of the color processing apparatus according to the first embodiment. 5 is a flowchart for explaining color conversion profile creation processing executed by the color processing apparatus. The figure which shows a mode that the color discrimination threshold with respect to each of 25 colors which MacAdam created was plotted in CIELAB space. The figure explaining the outline | summary of the creation method of uniform color perception space. 7 is a flowchart for explaining correction matrix generation processing. The flowchart explaining the production | generation process of B2ALUT. FIG. 6 is a block diagram illustrating a processing configuration example of a color processing apparatus according to a second embodiment. The figure which shows an example of UI for inputting the production | generation conditions of uniform grid UG _UCAS .

  Hereinafter, a color processing apparatus and a color processing method according to an embodiment of the present invention will be described in detail with reference to the drawings. In addition, an Example does not limit this invention concerning a claim, and all the combinations of the structure demonstrated in an Example are not necessarily essential for the solution means of this invention.

[Device configuration]
The block diagram of FIG. 2 shows a configuration example of an information processing apparatus that functions as the color processing apparatus of the embodiment. The CPU 201 executes an operating system (OS) or a program stored in the ROM 209 or the storage unit 203 using the main memory 202 such as a RAM as a work memory, and controls a configuration to be described later via the system bus 206. The storage unit 203 is an HDD, an SSD, or the like, and stores programs and various data for realizing color processing to be described later.

  Connected to the interface 204 are an operation unit 207 such as a keyboard and a mouse, a colorimeter 101, a recording medium 210 such as a memory card and a USB memory, and the like. A monitor 211 is connected to the video card (VC) 205. The CPU 201 displays information indicating a user interface (UI), processing progress, processing results, and the like on the monitor 211.

  For example, the CPU 201 loads an application program (AP) stored in the storage unit 203 or the recording medium 210 into a predetermined area of the main memory 202 in accordance with a user instruction input via the operation unit 207. Then, the AP is executed, and the UI is displayed on the monitor 211 according to the AP.

  Next, the CPU 201 inputs various data stored in the storage unit 203 and the recording medium 210 and the colorimetric values from the colorimeter 101 according to the UI operation by the user, and loads them into a predetermined area of the main memory 202. Then, predetermined arithmetic processing is performed on various data loaded into the main memory 202 in accordance with the AP. Then, the CPU 201 displays the calculation processing result on the monitor 205 or stores it in the storage unit 203 or the recording medium 210 in accordance with the UI operation by the user.

  Note that the CPU 201 can also exchange programs, data, and arithmetic processing results with a server device on a wired or wireless network via the interface 204. In addition, a tablet computer can be used as the information processing apparatus. In this case, a touch panel superimposed on the screen of the monitor 211 is the operation unit 207.

[Create color conversion profile]
A processing configuration example of the color processing apparatus 100 according to the first embodiment that creates a color conversion profile is shown in the block diagram of FIG. Note that the processing configuration and functions for creating the color conversion profile shown in FIG. 3 are realized by the CPU 201 executing the color processing AP. The color conversion profile creation process executed by the color processing apparatus 100 will be described with reference to the flowchart of FIG.

  The colorimetric value acquisition unit 102 acquires a data set representing the color reproduction characteristics of the device for which a color conversion profile is to be created from the colorimeter 101 or the recording medium 210 (S11). The device for creating the color conversion profile is, for example, a monitor or a printer. In the following description, the device to be created is described as a printer. Accordingly, the acquired data set indicates, for example, the correspondence between predetermined CMYK values and measured values.

  The colorimetric value acquisition unit 102 inputs, for example, a data file storing a data set in which the color reproduction characteristics of the printer are measured in advance from the recording medium 210 in accordance with a user instruction input by the operation unit 207. The measured value may be a psychophysical quantity such as tristimulus values XYZ, or a standard color space value such as CIEL * a * b * values. However, when the measured value is the tristimulus value XYZ, the colorimetric value acquisition unit 202 converts the acquired tristimulus value XYZ into a standard color space value such as a CIEL * a * b * value.

  The correction parameter acquisition unit 103 corrects distortion for the perception in the PCS such as the CIEL * a * b * space from the storage unit 203 or the recording medium 210, and converts the PCS into a color space equivalent to human perception. The correction parameter is acquired (S12). Hereinafter, a color space that is uniform with respect to human perception is referred to as a “uniform color perception space” or “UCAS (uniform color apparance space)”. Although described in detail later, the correction matrix generation unit 104 generates a correction matrix for rearranging the PCS uniform grid in a perceptual manner using correction parameters (S13).

The color gamut calculation unit 105 converts the measurement value included in the data set acquired by the colorimetric value acquisition unit 202 into the color value of the uniform color perception space using the correction parameter (S14). That is, the color gamut calculation unit 105 converts the measurement value indicating the color gamut of the creation target device into a uniform color perception space, thereby representing a data set indicating the color gamut Gamut _UCSA in the uniform color perception space of the creation target device. Is generated.

The multidimensional LUT creation unit 106 generates a multidimensional lookup table (hereinafter referred to as B2ALUT) to be stored in the BtoA tag using a data set indicating the correction matrix and the color gamut Gamut _UCSA of the creation target device, which will be described in detail later. (S15). The profile generation unit 107 generates a color conversion profile in which the correction matrix and the B2ALUT generated by the multidimensional LUT generation unit 106 are stored in the BtoA tag (S16).

  The color conversion profile is stored in the storage unit 203, the recording medium 210, and the like, and is used in the color matching module (CMM) as a color conversion profile for an image output device that is a creation target device.

Uniform color perception space and correction parameters The uniform color perception space is a color space that improves the color difference uniformity and hue linearity of the conventional standard color space represented by the CIEL * a * b * space. For example, FIG. 5 shows how the color discrimination thresholds (see Non-Patent Document 2) for each of the 25 colors created by MacAdam are plotted in the CIELAB space. For the sake of explanation, FIG. 5 is a graph in which the MacAdam color discrimination threshold (hereinafter referred to as MacAdam ellipse) is enlarged ten times and only chromaticity information is plotted on the a * -b * plane.

  Each oval figure shown in Fig. 6 shows the range that humans recognize as the same color, and the area of the figure is relatively small for low-saturation colors, and for high-saturation colors, especially blue and green The area of the figure becomes very large. In other words, humans can discriminate colors even when the distance in the color space is small for low-saturation colors, and colors can be distinguished even if the distance in the color space is large for high-saturation blue and green colors. I can't. In other words, the CIEL * a * b * space does not match human perception. The shape of the figure is also distorted in various directions. This indicates that the line on the color space that humans recognize as the same color is expressed in a curved manner on the CIEL * a * b * space. A color space in which distortion of the CIEL * a * b * space with respect to human perception is improved is a uniform color perception space.

  An outline of a method for creating a uniform color perception space will be described with reference to FIG. First, as shown in FIG. 7A, lattice data is set in a color space that is non-uniform to human perception (hereinafter, non-uniform color perception space) such as a CIEL * a * b * space. Then, as shown in FIG. 7 (b), the control point set at the boundary of the lattice area is moved. At that time, control point movement method and amount, and internal movement accompanying the movement of the control point so that the elliptic data represented by the MacAdam color discrimination threshold becomes a perfect circle of the same size in the entire color space. The ratio is optimized (see Patent Document 2).

In this way, by creating the uniform color perception space shown in FIG. 6 (c), it is possible to create an intelligent space with high color difference uniformity and hue linearity over the entire color space. Note that the correspondence between the coordinates (L, a, b) before the movement of each grid point of the grid data described above and the coordinates (L _u , a _u , b _u ) after the movement is represented by an LUT (hereinafter referred to as Lab → UCAS conversion LUT). ). Then, by performing an interpolation operation using the Lab → UCAS conversion LUT, the CIEL * a * b * value can be easily converted into a color value in the uniform color perception space (hereinafter referred to as UCAS value).

  That is, the correction parameter acquisition unit 203 acquires Lab → UCAS conversion LUT as a correction parameter (S13). Further, the color gamut calculation unit 105 converts the measurement value acquired by the colorimetric value acquisition unit 202 into the color value of the uniform color perception space using the Lab → UCAS conversion LUT (S14).

In the following, each axis of the uniform color perception space corresponding to each of the L *, a *, and b * axes of the CIEL * a * b * color space is represented by L _u , a _u , and b _u . When the PCS is not a CIEL * a * b * space, the correction parameter acquisition unit 203 acquires a correction parameter corresponding to the PCS, that is, a PCS → UCAS conversion LUT.

● Correction matrix generator In the following, the following names are used for the grid of PCS and uniform color perception space.
UG _PCS1 : PCS uniform grid,
UG _UCAS : _Uniform grid of uniform color perception space,
NG _PCS2 : A non-uniform grid obtained by inversely converting UG _UCAS to PCS using a PCS → UCAS conversion LUT.

The correction matrix generation process (S13) generates a matrix for distorting the arrangement of the UG _{PCS1 so} that the UG _PCS1 has a perceptually uniform interval. Correction matrix can be calculated from the correspondence between the UG _PCS1 and NG _PCS2.

The correction matrix generation process (S13) will be described with reference to the flowchart of FIG. The correction matrix generation unit 104 generates a _UGUCAS by equally dividing the numerical range of each axis of the uniform color perception space (S71). The numerical range is the boundary of the lattice area of the correction parameter (Lab → UCAS conversion LUT), and is defined as follows, for example.
0 ≤ L _u ≤ 100,
-100 ≤ a _u ≤ 100,
-100 ≤ b _u ≤ 100.

In this embodiment, the number of divisions in the numerical range of each axis is set to 16, and a uniform grid of 17 ³ = 4913 grid points is generated.

Next, the correction matrix generation unit 104 converts the L _u a _u b _u value of each grid point of UG _UCAS into a CIEL * a * b * value using the Lab → UCAS conversion LUT, and calculates NG _PCS2 (S72). Then, to generate a correction matrix from the corresponding relationship between the UG _PCS1 and NG _PCS2 (S73).

The correction matrix is, for example, a 3 × 3 conversion matrix. The matrix coefficient is optimized using an optimization method such as the attenuation least squares (DLS) so as to reduce the color difference between the result of converting the input data (UG _PCS1 ) by the correction matrix and the NG _PCS2 .

The DLS (dumped least square) method is a method that determines the processing parameters so that the difference between the target data string and the data string after processing the input data string with the processing parameter (matrix, etc.) approaches the target value string. is there. That is, the matrix coefficient that minimizes the evaluation value E of the following equation is calculated.
E = ΣEi = Σ√ {(L _u iL * i) ² + (a _u ia * i) ² + (b _u ib * i) ² }… (1)
Where Ei is the evaluation value of grid point i,
(L * i, a * i, b * i) is the input data (value of grid point i of UG _PCS1 ),
(L _u i, a _u i, b _u i) is the target value (value of grid point i in NG _PCS2 ),
The range of Σ operation is i = 1 to N (N = 4913 in this embodiment).

● Multi-dimensional LUT creation part The multi-dimensional LUT generation process (S15) applies a correction matrix to the PCS uniform grid UG _PCS1 to generate device-dependent signal values (output data) corresponding to each grid point after conversion. This is a process for obtaining B2ALUT. The device-dependent signal value corresponding to each lattice point after conversion is searched in the uniform perceptual color space.

The B2ALUT generation process (S15) will be described with reference to the flowchart of FIG. The multi-dimensional LUT creation unit 106 applies the correction matrix to the PCS uniform grid UG _PCS1 as shown in the following formula, and associates the PCS grid point arrangement with the uniform grid UG _UCAS in the uniform color perception space (S81). . In other words, the PCS grid points are rearranged perceptually equally. Hereinafter, the grid points after rearrangement are referred to as “uniform color perception grid points”.
┌ ┐ ┌ ┐
│L * t│ │L * │
│a * t│ = M│a * │… (2)
│b * t│ │b * │
└ ┘ └ ┘
┌ ┐
│m1 m2 m3│
M = │m4 m5 m6│
│m7 m8 m9│
└ ┘
Where M is the correction matrix,
(L *, a *, b *) is the coordinate (color value) of the grid point of UG _PCS1 ,
(L * t, a * t, b * t) are the coordinates (color values) of the perceptual uniform grid points.

Next, the multidimensional LUT creation unit 106 corresponds to the coordinates (L * t, a * t, b * t) of each uniform color perception grid point by an interpolation operation using a correction parameter (Lab → UCAS conversion LUT). A color value of the uniform color perception space is calculated (S82). Then, using the data set indicating the color gamut Gamut _UCSA of the creation target device generated by the color gamut calculation unit 105 in step S14 and the color values of the uniform color perception grid points, a device corresponding to the uniform color perception grid points A dependent signal value is calculated (S83).

That is, the color values included in the data set surrounding the color values of the uniform color perception grid points are searched. Then, a device-dependent signal value corresponding to the uniform color perception grid point is calculated by interpolation of a device-dependent signal value (included in the data set) corresponding to the colorimetric value obtained as a result of the search. At this time, if the color value of the uniform color perception grid point exists outside the color reproduction area Gamut _UCSA of the creation target device, color gamut mapping is performed (S84).

In color gamut mapping, for example, an out-of-gamut color specification for a uniform color perception grid point (hereinafter referred to as an out-of-gamut grid point) having a color value (hereinafter referred to as an out-of-gamut color value) existing outside the color reproduction range Gamut _UCSA The boundary of the color gamut Gamut _UCSA corresponding to the value is determined. Then, the device-dependent signal value corresponding to the out-of-gamut grid point is calculated by the interpolation calculation of the device-dependent signal value in the vicinity of the boundary corresponding to the out-of-gamut color value.

The boundary corresponding to out-of-gamut color values includes the shortest distance point (minimum color difference point), iso-lightness point (saturation compression point), out-of-gamut color values and a predetermined convergence point (for example, _Lu = The intersection of the line segment connecting the 50 points) and the boundary is used. According to such color gamut mapping, out-of-gamut grid points are mapped to the boundaries of the color reproduction gamut Gamut _UCSA .

  Thus, when creating a color conversion profile, perceptual interpolation errors can be equalized by creating a B2ALUT corresponding to a uniform grid in a uniform color perception space. Furthermore, since color gamut mapping is performed in a uniform color perception space, visually faithful color reproduction can be obtained.

  A color processing apparatus and color processing method according to a 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 may be omitted.

  In the first embodiment, an example in which a correction matrix in which lattice points are arranged perceptually and uniformly in the entire color space has been described. In the second embodiment, an example will be described in which a correction matrix is created in accordance with a user instruction in an area where interpolation accuracy is important (hereinafter, an area where accuracy is important).

  An example of the processing configuration of the color processing apparatus 100 of the second embodiment is shown in the block diagram of FIG. The processing configuration of the second embodiment illustrated in FIG. 9 is different from the processing configuration of the first embodiment illustrated in FIG. 3 in that a UI unit 111 and a condition setting unit 112 are provided. The UI unit 111 displays a user interface (UI) for inputting user instructions on the monitor 211 via the VC 205, and inputs user instructions via the operation unit 207.

FIG. 10 shows an example of a UI for inputting the uniform lattice UG _UCAS generation conditions. The user can select whether to input color gamut information indicating a precision-critical area from a data file or a range of chromaticity values by using a radio button. When the color gamut setting radio button is selected, the user inputs a data file name by the input unit 1001 or selects a data file. In addition, when the range setting radio button is selected, the user inputs a range of chromaticity values indicating an accuracy-oriented area using the input unit 1002. Further, the user can specify the number of divisions of the uniform color perception space by the input unit 1003.

When the user presses (or touches) the OK button, the condition setting unit 112 inputs the generation conditions (information indicating the accuracy-critical area and the number of divisions) set in the UI. The condition setting unit 112 converts the accuracy-critical area into a uniform color perception space using the PCS → UCAS conversion LUT. Then, the accuracy-important area after conversion is included, and an area that is positive / negative symmetric with respect to the a _u axis and that is positive / negative symmetric with respect to the b _u axis is set as a setting range of the uniform grid _{UGUCAS in} the uniform color perception space.

The correction matrix generation unit 104 receives the setting conditions (the setting range of the uniform grid UG _UCAS and the specified number of divisions), generates a uniform grid UG _UCAS based on the setting conditions (S71), and generates a correction matrix (S73). ). In this way, by limiting the region used for the B2ALUT generation process (S15) to the accuracy-oriented region, the interval between the lattice points can be narrowed, and the interpolation accuracy can be improved.

[Modification]
In the above-described embodiments, an example of using a correction matrix for rearranging PCS lattice points in a perceptual manner has been described, but other correction parameter formats such as a combination of a correction matrix and a one-dimensional LUT may be used.

  In the above embodiment, a CMYK input printer has been described as an example of the image output device. However, for example, the color conversion profile creation processing of other image output devices such as an RGB input printer, projector, and display is similarly performed. Is possible.

  In the above embodiment, an example in which the CIEL * a * b * space or the CIEXYZ space is used as the reference color space has been described. However, the CIEL * u * v * space or the JCh space in CIECAM02 is used as the reference color space. May be used.

[Other Examples]
The present invention supplies a program that realizes one or more functions of the above-described embodiments to a system or apparatus via a network or a storage medium, and one or more processors in a computer of the system or apparatus read and execute the program It can also be realized by processing. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

  102 ... Measurement value acquisition unit, 104 ... Correction matrix generation unit, 105 ... Color gamut calculation unit, 106 ... Multidimensional LUT creation unit

Claims (13)

Acquisition means for acquiring a data set including measurement values of colors output by the image output device;
A first correction parameter for converting a color value of the reference color space into a color value of the uniform color perception space, and Generating means for generating correction parameters;
A calculation means for converting a measurement value included in the data set using the first correction parameter and calculating a color value indicating a color gamut in the uniform color perception space of the image output device;
A color processing apparatus comprising: a creating unit that creates a table for converting a color value of the reference color space into a signal value depending on the image output device based on the second correction parameter and the color reproduction range.   The generating means calculates a non-uniform grid obtained by inversely transforming the second grid for equally dividing the uniform color perception space into the reference color space using the first correction parameter, and the non-uniform grid and the non-uniform grid 2. The color processing apparatus according to claim 1, wherein the second correction parameter is generated from a correspondence relationship of the first lattice.   The creation means searches for a color value indicating the color gamut surrounding the color value of a grid point of a uniform color perception grid in which the first grid is rearranged using the second correction parameter, and 3. The table according to claim 1 or 2, wherein the table is created by calculating a signal value depending on the image output device corresponding to a grid point of the uniform color perception grid based on a color value obtained as a result. Color processing device.   The creating means interpolates a signal value included in the data set corresponding to a color value obtained as a result of the search, and depends on the image output device corresponding to a grid point of the uniform color perception grid. 4. The color processing device according to claim 3, wherein the signal value is calculated.   5. The color processing apparatus according to claim 3, wherein the creating unit performs color gamut mapping of color values of lattice points of the uniform color perception grid not included in the color reproduction gamut to boundaries of the color reproduction gamut. .   6. The color processing apparatus according to claim 1, wherein the generation unit generates a correction matrix as the second correction parameter.   7. The color processing apparatus according to claim 1, further comprising means for generating a color conversion profile for the image output device that stores the second correction parameter and the table.   8. The color processing apparatus according to claim 1, further comprising an input unit that inputs information indicating a generation condition of the second lattice.   Further, setting means for setting a setting range obtained by converting the setting range of the second grid included in the generation condition into the uniform color perception space using the first correction parameter as the setting condition of the second grid. 9. The color processing apparatus according to claim 8, comprising:   10. The color processing apparatus according to claim 9, wherein the generation unit sets the second grid in the uniform color perception space according to the generation condition and the setting condition. Acquire a data set containing the measured values of the color output by the image output device,
A first correction parameter for converting a color value of the reference color space into a color value of the uniform color perception space, and Generate correction parameters,
Converting the measurement value included in the data set using the first correction parameter, calculating a color value indicating a color gamut in the uniform color perception space of the image output device;
A color processing method for creating a table for converting a color value of the reference color space into a signal value depending on the image output device based on the second correction parameter and the color gamut.   11. A program for causing a computer to function as each unit of the color processing apparatus according to claim 1.   A computer-readable recording medium on which the program according to claim 12 is recorded.

Images