JP2006211578A - Conversion lut creation apparatus and image processing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To acquire conversion coefficients, which can more reduce calculation time and scarcely degrade color gradation property, in 3D LUT creation. <P>SOLUTION: CMYK patches are printed and measured in a dCMYK patch printing/measurement processing part 106, and a 3D LUT 104 is created in an sRGB-dCMYK LUT creation processing part 105 using the measured data. In addition, each of L*a*b* entried to an initial 3D LUT is converted into sRGB based on the initial 3D LUT in an L*a*b*-sRGB conversion processing part 101, and then converted into dCMYK based on the 3D LUT 104 in an sRGB-dCMYK conversion processing part 102 to be printed and measured in the dCMYK. Subsequently, the sRGB is corrected until color blurring is eliminated, and a 3D LUT 108 is synthesized in a 3D LUT synthetic processing part 107 from the finally acquired 3D LUT 103 and 104. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a conversion LUT creation apparatus and an image processing method for creating an LUT for converting a color space from a device-independent color space to a device-dependent color space.

  Conventionally, in color matching between input devices having different color spaces, color matching processing using an ICC (International Color Consortium) profile has been performed. Here, the ICC profile is an industry standard color profile whose profile structure is open to the public, and is actively used as a color conversion profile in some OS (opetating system) and applications.

  As shown in FIG. 6, this ICC profile is composed of a header part and a body part. The header part includes a creation date and time, a device class, and a device-independent color space called PCS (Profile Connection Space). (Hereinafter, a device-independent color space is referred to as a “device-independent color space”). PCS includes CIE XYZ color space and CIE L * a * b * color space. On the other hand, the main body includes a table of conversion processing from device color space to PCS (A2Bx, x = 0, 1, 2) and conversion processing from PCS to device color space (B2Ax, x = 0, 1, 2, 1). ) Table is stored. In addition, a white point (wtpt) of the device, color reproduction range information (gamt), a description of the profile (desc), and the like are described in the main body.

  The B2Ax table includes an L * a * b * -CMYK LUT. This L * a * b * -CMYK LUT prints, for example, a 9 × 9 × 9 × 9 CMYK combination patch. Then, the printed patch is measured (S703 in FIG. 8), and based on the measurement result, a L * a * b * -CMYK LUT having a combination of 33 × 33 × 33 is created (S704 in FIG. 8). .

  Next, an example of the color matching process on the assumption that the PCS is L * a * b * which is a device-independent color space will be described with reference to FIG. RGB is first converted into L * a * b * in a device-independent color space based on the correspondence relationship of the A2Bx table in the profile in which the input device RGB selected from the input device ICC profile group is defined ( S201), and then the obtained L * a * b * is a table of B2Ax in the ICC profile in which the output device CMYK selected from the output device ICC profile group is defined L * a * b * -CMYK Based on the correspondence relationship of the LUT, it is converted into an output device CMYK in a device-dependent color space (S202). The output device CMYK is binarized (S206) and printed (S207).

Japanese Patent Laid-Open No. 10-79865 JP-A-8-130655

  By the way, according to the definition of the ICC profile, L * a * b * is a very wide color space where L * is 0 to 100, a * is -128 to 127, and b * is -128 to 127. .

  On the other hand, when the entire L * a * b * color space is the color space indicated by 601 in FIG. 10, the device CMYK color space of the output device occupies the color space indicated by 602 in FIG. Since the ratio of the CMYK color space to the entire L * a * b * color space is usually only about ¼ to ８, the L * a * b * -CMYK conversion processing unit 202 uses, for example, Patent Document 2 It is conceivable to perform color space compression by the color space compression (gamut mapping) technique disclosed in FIG.

  However, when color space compression is performed by this color space compression method, generally, as the compression rate increases, pseudo contours, quantization errors, and the like are likely to occur, and these pseudo contours, quantization errors, and the like are to be removed. As a result, there is a problem in that the calculation time increases.

  Therefore, the present invention solves the above-described problems, suppresses the occurrence of pseudo contours and quantization errors in creating a conversion LUT for converting from a device-independent space to a device-dependent color space, and calculates the calculation time. It is an object of the present invention to provide a conversion LUT creation apparatus and an image processing method that can shorten the image processing time.

  The invention of claim 1 is a conversion LUT creation apparatus for creating a 3DLUT for converting a color value from a device-independent color space to a device-dependent color space, and the device output by the output device having the device-dependent color space An intermediate / device dependent / color space conversion LUT for converting color values from the intermediate color space to the device dependent color space, generated based on the measurement result of the patch having the dependent color space, and the device independent color space The color value is converted to the color value of the intermediate color space based on a predetermined correspondence relationship, and the obtained color value is converted to the color value of the device dependent color space based on the intermediate / device dependent / color space conversion LUT Print, measure, and repeat this procedure while correcting the color values of the intermediate color space in the correspondence until there is no color shift in the print result. And a device-independent / intermediate / color space conversion LUT for converting color values from the device-independent color space to the intermediate color space having a correspondence relationship between the resulting color values. The image processing apparatus includes a synthesis processing unit that creates the 3DLUT.

  In the first aspect of the invention, the intermediate color space may be a color space that does not depend on the device color space.

  In the invention of claim 1 or 2, the intermediate color space can have a color reproduction range narrower than the device-independent color space and wider than the device-dependent color space.

  In the invention according to any one of claims 1 to 3, the device-independent / intermediate / color space conversion LUT has the same number of lattice points as the 3DLUT, and can be larger than the intermediate / device-dependent / color space conversion LUT.

  According to a fifth aspect of the present invention, there is provided a conversion LUT creation apparatus for creating a 3DLUT for converting a color value from a device-independent color space to a device-dependent color space, the color value of the first intermediate color space, and the color value as a predetermined value. A first intermediate / device-dependent / color space conversion LUT in which color values of the device-dependent color space obtained by conversion using a conversion function are associated with each other, and color values of a patch having the first intermediate color space are converted into the first color values. A color generated based on a measurement result of a patch having the device-dependent color space, which is converted to a color value of the device-dependent color space based on an intermediate / device-dependent / color space conversion LUT and output by a predetermined output device The second intermediate / first intermediate / color space conversion LUT for converting the value from the intermediate color space to the device-dependent color space and the color values of the device-independent color space have a predetermined correspondence relationship. Converting the color value of the second intermediate color space to the color value of the first intermediate color space based on the second intermediate / first intermediate / color space conversion LUT; and 1. Convert to the device-dependent color space color value based on the intermediate / device-dependent / color space conversion LUT, print, and measure, and repeat this procedure until there is no color shift in the print result. 2) Device-independent for converting color values from the device-independent color space to the second intermediate color space, having a corresponding relationship between the color values obtained by repeatedly correcting the color values in the intermediate color space. The image processing apparatus is characterized by comprising a combining processing means for combining the second intermediate / color space conversion LUT to create the 3DLUT.

  In the invention of claim 5, the second intermediate color space may be a device-independent color space.

  In the invention of claim 5, the first intermediate color space may be a device-dependent color space.

  In any one of claims 5 to 7, the first and second intermediate color spaces may have a color reproduction range narrower than the device-independent color space and wider than the device-dependent color space.

  8. The device-dependent / second intermediate / color space conversion LUT according to any one of claims 5 to 7, wherein the number of lattice points is equal to that of the 3DLUT and is larger than the second intermediate / first intermediate / color space conversion LUT. it can.

  8. The device-dependent / second intermediate / color space conversion LUT according to any one of claims 5 to 7, wherein the number of lattice points is equal to that of the 3DLUT and can be larger than the first intermediate / device-dependent / color space conversion LUT. .

  The second intermediate / first intermediate / color space conversion LUT may have the same number of lattice points as the first intermediate / device-dependent / color space conversion LUT.

  The invention according to claim 12 sets an intermediate color space different from the device-independent color space and the output device-dependent color space, and is different from the device-independent color space based on the measurement value from the output device. Obtaining a conversion table from the device-independent color space to the output device-dependent color space, and combining the conversion table and the conversion table from the device-independent color space prepared in advance to the intermediate color space to output the device from the device-independent space And a step of creating a conversion table to the dependency space.

  In the invention of claim 12, the intermediate color space can be a color space that does not depend on the output device color space.

  In the invention of claim 12 or 13, the color reproduction range of the intermediate color space is narrower than the device-independent color space and can be wider than the output device color space.

  According to the present invention, since it is configured as described above, it is possible to further reduce the calculation time in creating a 3DLUT (conversion table) for performing conversion from a device-independent color space to a device-dependent color space. It is possible to obtain a conversion coefficient in which the color gradation is not easily lost.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

<First Embodiment>
FIG. 1 shows a first embodiment of the present invention. In FIG. 1, reference numeral 107 denotes a 3DLUT compositing processing unit, which converts a 3DLUT 108 used in the L * a * b * -dCMYK conversion into a device independent color space L * a * b * and a device independent color space sRGB. The corresponding 3DLUT 103 and the 3DLUT 104 in which sRGB in the device-independent color space and dCMYK in the device-dependent color space (hereinafter referred to as “device-dependent color space”) are associated with each other are synthesized.

  First, a method of creating the 3DLUT 104 that associates sRGB in the device-independent color space with dCMYK in the device-dependent color space will be described. In the dCMYK patch printing / measurement processing unit 106, 9 × 9 × 9 × 9 CMYK patches are printed by a printer as an output device, the printed CMYK patches are measured, and measurement data is obtained. Using this acquired measurement data, the sRGB-dCMYK LUT creation processing unit 105 creates a 3DLUT 104 that is a 17 × 17 × 17 grid sRGB-dCMYK LUT. As this creation method, for example, the method described in Patent Document 2 can be adopted, and detailed description of this method is omitted. An example of the 3DLUT 104 that is the obtained sRGB-dCMYK LUT is shown in FIG.

  Next, a method of creating the 3DLUT 103 in which sRGB in the device-independent color space is associated with dCMYK in the device-dependent color space will be described. This 3DLUT 103 is an LUT for obtaining RGB in the sRGB color space, which is a device-independent color space, from L * a * b * in the L * a * b * color space, which is a device-independent color space. Can be color-converted uniquely from L * a * b *.

  The 3DLUT 103 is finally obtained, and the initial 3DLUT of the 3DLUT 103 corresponds to 35937 sRGB in advance for 35937 (= 33 × 33 × 33) L * a * b *. It has been made.

  35937 L * a * b * of the initial 3DLUT are sequentially converted into sRGB based on the initial 3DLUT in the L * a * b * -sRGB conversion processing unit 101, respectively, and then obtained. The sRGB is converted into dCMYK in the sRGB-dCMYK conversion processing unit 102 based on the already created 3DLUT 104 (that is, sRGB-dCMYK LUT). The obtained CMYK is binarized and printed, then printed and measured, and the measurement result is analyzed. When there is no color misregistration, sRGB entered in the initial 3DLUT is adopted as sRGB for the L * a * b *. On the other hand, if there is a color misregistration, the sRGB entered in the initial 3DLUT is corrected until the color misregistration disappears, and the above processing is repeated using the 3DLUT with the corrected sRGB. An example of the 3DLUT 103 obtained in this way is shown in FIG.

  When the final 3DLUT 103 is obtained in this manner, the 3DLUT 103 which is the L * a * b * -sRGB LUT of 33 × 33 × 33 lattice and the sRGB-dCMYK LUT of the 17 × 17 × 17 lattice described above. The 3DLUT 108 is synthesized by the 3DLUT synthesis processing unit 107 from the two 3DLUTs of the 3DLUT 104.

  Next, the synthesis processing method of the 3DLUT 108 will be described in more detail with reference to FIG. As described above, the 3DLUT 104 is an sRGB-dCMYK LUT and has 17 points of grids in each of the R, G, and B axes, that is, 4913 (= 17 × 17 × 17) grid points. Corresponding color conversion values cmyk are preset in 4913 lattice points.

Then, the sRGB value at each grid point in the 3DLUT 103 (L * a * b * -sRGB LUT having 35937 (= 33 × 33 × 33) grid points) is input sRGB (in FIG. 4). 8), 8 lattice points surrounding this input sRGB are obtained, and the respective lattice point positions are R0G0B0 to R1G1B1, as shown in FIG. When the color conversion values at these lattice points are set to cmyk000 to cmyk111, the color conversion value cmyk for an arbitrary input sRGB value is obtained by tetrahedral interpolation as follows.
cmyk = cmyk000
+ C1 × ΔR / (R1−R0)
+ C2 × ΔG / (G1-G0)
+ C3 × ΔB / (B1−B0)
However, ΔR = R−R0, ΔG = G−G0, and ΔB = B−B0.

Here, c1, c2, and c3 are classified into the following six cases (1) to (6).
(1) When ΔR>ΔG> ΔB c1 = cmyk100−cmyk000,
c2 = cmyk110-cmyk100,
c3 = cmyk111-cmyk110
(2) When ΔR>ΔB> ΔG c1 = cmyk100−cmyk000,
c2 = cmyk111-cmyk101,
c3 = cmyk101-cmyk100
(3) When ΔB>ΔR> ΔG, c1 = cmyk101−cmyk001,
c2 = cmyk111-cmyk101,
c3 = cmyk001-cmyk000
(4) When ΔG>ΔR> ΔB c1 = cmyk110−cmyk010,
c2 = cmyk010-cmyk000,
c3 = cmyk111-cmyk110
(5) When ΔG>ΔB> ΔR, c1 = cmyk111−cmyk011,
c2 = cmyk010-cmyk000,
c3 = cmyk011-cmyk010
(6) When ΔB>ΔG> ΔR, c1 = cmyk111−cmyk011,
c2 = cmyk011-cmyk001,
c3 = cmyk001-cmyk000
By performing this calculation for all sRGB values in the 3DLUT 103, the 3DLUT 108, which is an L * a * b * -dCMYK LUT having a 33 × 33 × 33 lattice, is obtained.

  As described above, in this embodiment, the example in which the intermediate color space is the sRGB color space has been described. However, the present invention is not limited to this, and instead of this sRGB color space, another output device-independent color space is used. Can do.

The color reproduction range includes the relationship between the L * a * b * color space, the intermediate color space, and the output device-dependent color space.
It is desirable that L * a * b * color space> intermediate color space> output device-dependent color space.

The present embodiment has the following advantages compared to the conventional example in which 3DLUT which is L * a * b * -dCMYK LUT of 33 × 33 × 33 lattice is directly calculated from the measurement patch. That is,
(A) In this embodiment, since the correspondence to dCMYK is obtained by calculation from the sRGB color space narrower than the L * a * b * color space, the gamut compression rate is relatively small, and color conversion is performed. The gradation is not easily broken by
(B) The number of grid points of the 3DLUT 104, which is the 17 × 17 × 17 grid sRGB-dCMYK LUT, obtained by calculation is 17 points, and can be reduced to half of the 33 points of the conventional method. The time required for calculation has been shortened.
(C) Since the 3DLUT 103, which is an L * a * b * -sRGB LUT having a 33 × 33 × 33 lattice, is adjusted with time and effort, the gradation is lost due to the L * a * b * -sRGB conversion. Can be prevented in advance.

  In this way, in the creation of a 3DLUT for performing conversion from a device-independent color space to a device-dependent color space, it is possible to reduce the calculation time and obtain a conversion coefficient that does not easily disturb the color gradation. it can.

<Second Embodiment>
FIG. 5 shows a second embodiment of the present invention. In FIG. 5, reference numeral 309 denotes a 3DLUT compositing processing unit, which converts the 3DLUT 310 used in the L * a * b * -dCMYK conversion into L * a * b * in the device-independent color space and sRGB in the device-independent color space. A corresponding 3DLUT 304, a 3DLUT 305 in which sRGB in a device-independent color space is associated with dRGB in a device-dependent color space, and a 3DLUT 306 in which dRGB in a device-dependent color space is associated with dCMYK in a device-dependent color space. To be synthesized.

First, a 3DLUT 306 that associates dRGB in the device-dependent color space with dCMYK in the device-dependent color space is a 17 × 17 × 17 lattice dRGB-dCMYK LUT, and is a known conversion, for example,
K = min (255-R, 255-G, 255-B)
C = 255-RK
M = 255-G-K
Y = 255-BK
Created by.

  Next, a method of creating the 3DLUT 305 in which sRGB in the device-independent color space is associated with dRGB in the device-dependent color space will be described. The dRGB patch generation / printing / measurement processing unit 311 generates a dRGB patch of 9 × 9 × 9 steps, the generated dRGB patch is converted into dCMYK based on the 3DLUT 306, and is printed by a printer as an output device. The printed dCMYK patch is measured. Then, a 3DLUT 305 (17 × 17 × 17 grid sRGB-dCMYK LUT) is created by the sRGB-dRGB LUT creation processing unit 307 using the obtained measurement data.

  DRGB in the dRGB color space, which is a device-dependent color space of the 3DLUT 305, can be uniquely color-converted from sRGB in the sRGB color space, which is a device-independent color space. As dRGB for sRGB of this 3DLUT 305, patch measurement values are interpolated to increase the number of measurement values, and dRGB having a minimum color difference with respect to the target sRGB value may be obtained from among them. An optimal dRGB may be obtained based on human visual characteristics.

  Next, a method of creating the 3DLUT 304 in which L * a * b * in the device-independent color space and sRGB in the device-independent color space are associated with each other will be described. This 3DLUT 304 is finally obtained, and the initial 3DLUT of this 3DLUT 304 is obtained by previously calculating 35937 sRGB for 35937 (= 33 × 33 × 33) L * a * b *. It is a thing made to correspond.

  35937 L * a * b * of the initial 3DLUT are sequentially converted into sRGB based on the initial 3DLUT in the L * a * b * -sRGB conversion processing unit 301, and then obtained. In the sRGB-dRGB conversion processing unit 302, the sRGB is converted into dRGB based on the already created 3DLUT 305 (that is, sRGB-dRGB LUT), and the obtained dRGB is further converted in the dRGB-dCMYK conversion processing unit 302. Based on the already created 3DLUT 306 (ie, dRGB-dCMYK LUT), the data is converted into dCMYK. The obtained dCMYK is binarized and printed, then printed and measured, and the measurement result is analyzed. When there is no color misregistration, sRGB entered in the initial 3DLUT is adopted as sRGB for the L * a * b *. On the other hand, if there is a color misregistration, the sRGB entered in the initial 3DLUT is corrected until the color misregistration disappears, and the above processing is repeated using the 3DLUT with the corrected sRGB.

  When the final 3DLUT 304 (L * a * b * -SRGB LUT of 33 × 33 × 33 lattice) is obtained in this way, the device independent color space L * a * b * and the device independent color space A 3DLUT 304 corresponding to sRGB, a 3DLUT 305 corresponding to sRGB in the device-independent color space and dRGB in the device-dependent color space, and a 3DLUT 306 in which dRGB in the device-dependent color space and dCMYK in the device-dependent color space are related to each other. The 3DLUT 310 (L * a * b * -dCMYK LUT of 33 × 33 × 33 lattice) is synthesized by the 3DLUT synthesis processing unit 309.

  That is, in the 3DLUT synthesis processing unit 309, first, the 3DLUT 304 (L * a * b * -sRGB LUT) and the 3DLUT 305 (sRGB-dRGB LUT) are obtained by the same method as that described in the first embodiment. The 3DLUT, which is the L * a * b * -dRGB LUT obtained by combining, and the 3DLUT 306 (dRGB-dCMYK LUT) are combined in the same manner to create the 3DLUT 310.

  Therefore, according to the present embodiment, the same effect as that of the first embodiment can be obtained.

  Further, in the present embodiment, the number of measurement patches can be reduced from 9 × 9 × 9 × 9 to 9 × 9 × 9 compared to the first embodiment.

It is a block diagram which shows the 1st Embodiment of this invention. It is a figure which shows an example of the correspondence of sRGB of 3DLUT104 and dCMYK as a table. It is a figure which shows an example of the correspondence of L * a * b * of 3DLUT103 and sRGB as a table. 5 is an explanatory diagram for explaining a method of synthesizing 3DLUT 108. FIG. It is a block diagram which shows the 2nd Embodiment of this invention. It is a figure which shows the structure of an ICC profile. It is a figure which shows an example of the color conversion process structure in an ICC profile. It is a figure which shows the preparation procedure by the conventional method of conversion LUT in an ICC profile. It is explanatory drawing for demonstrating the conventional color matching process using an ICC profile. It is a figure which shows the color reproduction range of device CMYK in L * a * b * color space.

Explanation of symbols

101 L * a * b * -sRGB conversion processing unit 102 sRGB-dCMYK conversion processing unit 105 sRGB-dCMYKLUT creation processing unit 106 dCMYK patch printing / measurement processing unit 107 3DLUT synthesis processing unit 301 L * a * b * -sRGB conversion processing Unit 302 sRGB-dRGB conversion processing unit 303 dRGB-dCMYK conversion processing unit 307 sRGB-dRGB conversion processing unit 311 dRGB patch generation / print / measurement processing unit 309 3DLUT synthesis processing unit

Claims (14)

In a conversion LUT creation apparatus for creating a 3DLUT for converting a color value from a device-independent color space to a device-dependent color space,
Intermediate device for converting color values generated from the measurement result of the patch having the device dependent color space output from the output device having the device dependent color space from the intermediate color space to the device dependent color space Dependency / color space conversion LUT,
The color value of the device-independent color space is converted to the color value of the intermediate color space based on a predetermined correspondence relationship, and the obtained color value is converted to the device dependency based on the intermediate / device-dependent / color space conversion LUT Convert to color space color values, print, measure, and repeat this procedure while correcting the color values of the intermediate color space in the correspondence until there is no color shift in the printed results A device-independent / intermediate / color space conversion LUT for converting color values from the device-independent color space to the intermediate color space, having a corresponding relationship between the color values;
A conversion LUT creation apparatus comprising synthesis processing means for synthesizing and generating the 3DLUT.   2. The conversion LUT creation apparatus according to claim 1, wherein the intermediate color space is a color space that does not depend on the device color space.   3. The conversion LUT creation apparatus according to claim 1, wherein the intermediate color space has a color reproduction range narrower than the device-independent color space and wider than the device-dependent color space.   4. The conversion according to claim 1, wherein the device-independent / intermediate / color space conversion LUT has a lattice number equal to the 3DLUT and larger than the intermediate / device-dependent / color space conversion LUT. LUT creation device. In a conversion LUT creation apparatus for creating a 3DLUT for converting a color value from a device-independent color space to a device-dependent color space,
A first intermediate / device-dependent / color space conversion LUT in which a color value of the first intermediate color space is associated with a color value of the device-dependent color space obtained by converting the color value with a predetermined conversion function;
The device-dependent color value converted from the color value of the patch having the first intermediate color space to the color value of the device-dependent color space based on the first intermediate / device-dependent / color space conversion LUT and output by a predetermined output device A second intermediate / first intermediate / color space conversion LUT for converting a color value from the intermediate color space to the device-dependent color space, generated based on a measurement result of a patch having a color space;
The color value of the device-independent color space is converted to the color value of the second intermediate color space based on a predetermined correspondence relationship, and the obtained color value is converted to the second intermediate / first intermediate / color space conversion LUT. The color value of the first intermediate color space is converted to the color value of the device-dependent color space based on the first intermediate / device-dependent / color space conversion LUT, printed, and measured. The color value of the second intermediate color space in the correspondence relationship is repeatedly corrected until there is no color misregistration in the print result, and the color value having the correspondence relationship of the resulting color value is determined as the device independent. A device independent / second intermediate / color space conversion LUT for converting from a color space to the second intermediate color space;
A conversion LUT creation apparatus comprising synthesis processing means for synthesizing and generating the 3DLUT.   6. The conversion LUT creation apparatus according to claim 5, wherein the second intermediate color space is the device-independent color space.   6. The conversion LUT creation apparatus according to claim 5, wherein the first intermediate color space is the device-dependent color space.   8. The conversion LUT according to claim 5, wherein the first and second intermediate color spaces have a color reproduction range narrower than the device-independent color space and wider than the device-dependent color space. Creation device.   8. The device-dependent / second intermediate / color space conversion LUT according to claim 5, wherein the number of lattice points is equal to that of the 3DLUT and is larger than the second intermediate / first intermediate / color space conversion LUT. A featured conversion LUT creation device.   8. The device-dependent / second intermediate / color space conversion LUT according to claim 5, wherein the number of lattice points is equal to that of the 3DLUT and is larger than the first intermediate / device-dependent / color space conversion LUT. A conversion LUT creation device.   8. The conversion LUT according to claim 5, wherein the second intermediate / first intermediate / color space conversion LUT has the same number of lattice points as the first intermediate / device-dependent / color space conversion LUT. Creation device. An intermediate color space different from the device independent color space and the output device dependent color space is set, and the output device dependent color space is selected from an intermediate color space different from the device independent color space based on a measurement value from the output device. Obtaining a conversion table to
Creating a conversion table from a device-independent space to an output device-dependent space by combining the conversion table and a conversion table from the device-independent color space prepared in advance to the intermediate color space. An image processing method.   13. The image processing method according to claim 12, wherein the intermediate color space does not depend on the output device color space. 14. The image processing method according to claim 12, wherein a color reproduction range of the intermediate color space is narrower than the device-independent color space and wider than the output device color space.

Images