JP2006311257A - Color conversion definition generating method, profile generating method, color conversion definition generating apparatus, profile generating apparatus, color conversion definition generating program, and profile generating program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a color conversion definition generating method or the like for generating a color conversion definition for converting coordinate points in a color reproduction region of a printer into coordinate points in a color reproduction region of a print, wherein the immunity to a K process binding condition is enhanced to generate the color conversion definition whereby even a high lightness color can be reproduced on the print. <P>SOLUTION: A K value (K≤0) in response to Chroma=Max(R, G, B)-Min(R, G, B) at each point on a WMRY plane, a WYGC plane, and a WCBM plane is assigned to each point, and the K value is assigned to each point of whole color reproduction regions by carrying out an interpolation arithmetic operation by using them for boundary conditions. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention provides a three-dimensional color space (RGB color space) with R (red), G (green), and B (blue) as axes, depending on a device (for example, a printer) that mediates between images and image data. In the four-dimensional color space (CMYK color space) with the coordinate points in the color reproduction area of the device as axes of C (cyan), M (magenta), Y (yellow), and K (black) for printing. A color conversion definition creation method, a color conversion definition creation apparatus, and an information processing apparatus such as a computer are used as such a color conversion definition creation apparatus. Color conversion definition creation program to be operated, profile creation method for creating profiles linking different color spaces, profile creation device, and information processing device such as computer It relates profile creating program for operating as such the profile generation device.

  Conventionally, CMY data representing a combination of C, M, and Y density values (coordinate points in the CMY color space) is input as a device for performing high-quality color processing for printing on image data representing an image. , C, M, Y, and K are known to output CMYK data representing a combination of halftone% (coordinate points in the CMYK color space) (see, for example, Patent Document 1).

  This device performs color processing by inputting CMY data. Although there have been proposals for various improvements in recent years, this device is basically established to some extent. There are quite a few experts who can perform high quality color processing (this color processing is called "setup").

  In recent years, with the spread of color management technology, there is an increasing need to obtain high-quality CMYK data for printing based on color data other than CMY data. As an example, RGB data representing a combination of R, G, and B values (coordinate points in the RGB color space) is received, and a print image obtained by outputting with a printer based on the RGB data is obtained. It may be required to print an image that reproduces the color.

  When converting RGB data into CMYK data, it is necessary not only to convert the RGB data into CMYK data that can obtain the same color in colorimetry, but also into CMYK data with excellent printability. A major factor for the presence or absence of printability is the value of K. When converting RGB data into CMYK data that can obtain the same color in colorimetry, the value of K depends on the printing company, printing machine, etc. It is necessary to determine the value of K (according to the K version constraint).

  Even if RGB data can be converted into CMYK data with excellent printability and colorimetrically the same color using various methods, this is based on the RGB data. The color of the image output by a specific printer and the color of the image reproduced by printing match the area where the color reproduction area of the printer overlaps with the color reproduction area of the print. When the color reproduction area (printer profile outline) and the print color reproduction area (print profile outline) are significantly different (usually, the print profile outline is narrower), How is the color reproduction area of the print printed so that an image that is very close to the color of the image output by the printer and does not cause a sense of incongruity in the color tone is reproduced by printing? To convert the color (which is referred to as a gamut mapping) becomes a problem.

One excellent method has been proposed as a gamut mapping method (see Patent Document 2). In the method proposed in Patent Document 2, the mapping direction is determined on a device color space (for example, a device-dependent RGB color space), and the actual mapping is a common color such as an L ^* a ^* b ^* color space. If this method is adopted, it is possible to achieve both colorimetric fidelity in the vicinity of the gray axis and high color expression in the vicinity of the gamut (color reproduction region) surface.

  However, since the method proposed in Patent Document 2 cannot directly map RGB data to CMYK data including the value of K, the input RGB data and printing can be performed as in Patent Document 3, for example. Another device for handling RGB data having a color reproduction area sufficiently matching that of the print color reproduction area is interposed between the CMYK data for input, and the input RGB data and the RGB data of the other device Gamut mapping is performed in accordance with the method of the above-mentioned Patent Document 2, and then color matching is performed between the RGB data of the interposed device and the CMYK data for printing in consideration of the K plate constraint condition. It has been proposed. In the case of the method considered in Patent Document 3, it is necessary to actually prepare a device having a color reproduction area that sufficiently matches the print color reproduction area. Even if one device is not actually prepared, the virtual device RGB can be obtained from the above input RGB data by performing an operation in which a device having a color reproduction region that sufficiently matches the color reproduction region of printing is virtually prepared. It has been proposed to perform gamut mapping to data and perform color matching in consideration of K plate constraint conditions between RGB data of the virtual device and CMYK data for printing.

However, this patent document 4 only virtually contemplates a device having a color reproduction area that sufficiently matches the print color reproduction area. However, when examined in more detail, the color reproduction region of RGB data is (R, G, B) = (0, 0, 0) to (255, 255, 255) (here, the value 255 is the maximum value). For example, in the case of CMYK data, (C, M, Y, K) = (100, 100), even though it is a regular hexahedron and is mapped to, for example, the L ^* a ^* b ^* color space. , 100, 100) (here, C, M, Y, and K represent halftone dots, and the value 100 represents halftone dots and represents 100% (that is, the maximum value)). C, M, Y, K) = (0, 100, 100, 100), (100, 0, 100, 100), (100, 100, 0, 100) Black and B taste black exist, and more vertices (one 11 vertices) is present in the manner. Therefore, in the case of a printer that handles RGB data, strictly speaking, it is impossible to realize the same color reproduction area as the printing color reproduction area. The question is how to 'well' connect these differences. Further, in Patent Document 4, a virtual device having a color reproduction area that sufficiently matches a print color reproduction area is prepared conceptually, and a specific profile of the virtual device is not prepared. . The compatibility of the virtual device profile with the gamut mapping method proposed in the above-mentioned Patent Document 2 is greatly different. Therefore, it is also important how the virtual device profile is specifically defined. It is a problem.

  Further, regarding the K plate constraint condition, in the above-mentioned Patent Document 4, since the value of K is obtained from the minimum values of C, M, and Y, a satisfactory result can be obtained to some extent on the gray axis or in the vicinity of the gray axis. Although there is a problem, there is a problem that it is not possible to express a particularly dark high saturation color. Moreover, it is not only necessary to comply with the K version restriction conditions. There is a problem that even if the gray color gradation of the four CMYK plates is kept monotonous, it is difficult for the printing operator to accept the gradation inversion in any of the plates. For this reason, in addition to correctly observing the K plate constraint conditions on the gray axis, it is necessary to prevent the plates on the gray axis from being inverted.

  In Japanese Patent Application No. 2004-075544, these problems are solved, a virtual device profile is defined well, and a virtual device having a color reproduction area close to the print color reproduction area is prepared on the algorithm. Means have been proposed for correctly reflecting the K plate constraint condition on the gray axis. According to the proposal of Japanese Patent Application No. 2004-075544, for example, by combining with the method proposed in Patent Document 2, the K plate constraint condition is faithfully reflected on the gray axis with colorimetric fidelity and no gradation collapse. The color conversion definition from the RGB color space to the CMYK color space can be created.

  However, the proposal of Japanese Patent Application No. 2004-075544 has a problem that the resistance to the K plate constraint condition is not always sufficient. That is, when a K plate constraint condition is set such that the amount of K plate increases rapidly from a light color to a dark color, the result of interpolation corresponds to a high brightness color that can be reproduced only at K = 0 in the color reproduction region. At this point, a value of K> K> 0 is assigned, and there is a possibility that the originally intended high brightness color may not be reproduced on printing.

  Patent Document 5 discloses that on the gray axis, on each ridge line and diagonal line connecting each vertex of R, G, B, C, M, and Y and the vertex of W, and on R, G, B, C, and M. By performing an interpolation operation using the data assigned to each edge on the ridge line and each diagonal line connecting the vertices of Y and K and the vertices of the diagonal as boundary conditions, the entire data including the inside of the color reproduction region is obtained. , Creating a color conversion definition from the RGB color space to the CMYK color space is described.

However, in this patent document 5, an ink jet printer is assumed as a CMYK device, and in the case of an ink jet printer, the K plate constraint condition is not specified, so the problem of durability against the K plate constraint condition is not considered in the first place. . If the technique of Patent Document 5 is applied to printing and an interpolation operation is performed by designating a K plate constraint condition, as in the above-mentioned Japanese Patent Application No. 2004-077554, the result of interpolation is essentially K = 0. A high brightness color that can only be reproduced is assigned a K value of K> 0, and the originally intended high brightness color may not be reproduced on printing.
Japanese Patent Laid-Open No. 9-83824 JP 2001-103329 A JP 2004-007373 JP JP 2004-102489 A JP 2002-335413 A

  In view of the above circumstances, the present invention, for example, represents a coordinate point (RGB data) in a color reproduction area of a device in an RGB color space depending on a device such as a printer, and the printing color in a CMYK color space for printing. A color conversion definition creation method for creating a color conversion definition that improves resistance to K plate constraint conditions and can reproduce high brightness colors on printing when converting to coordinate points (CMYK data) in a reproduction region; Profile creation method, color conversion definition creation device, profile creation device, and color conversion definition creation program and profile creation program for operating an information processing device such as a computer as such a color conversion definition creation device or profile creation device The purpose is to provide.

The color conversion definition creating method of the present invention that achieves the above object is provided in the color reproduction region of the first device in the first RGB color space depending on the first device that mediates between the image and the image data. In a color conversion definition creating method for creating a color conversion definition for converting a coordinate point to a coordinate point in a printing color reproduction area in a CMYK color space for printing,
Between a second RGB color space depending on a virtual second device that mediates between an image and image data, having a color reproduction area that follows the color reproduction area of printing, and a predetermined common color space A profile creation process to create a virtual device profile;
Using the device profile of the first device and the virtual device profile created in the profile creation process, the coordinate point in the color reproduction area of the first device in the first RGB color space is determined as the second RGB. A first color conversion definition creating process for creating a first color conversion definition for converting to a coordinate point in the color reproduction region of the second device in the color space;
A second color conversion definition for converting a coordinate point in the color reproduction area of the second device in the second RGB color space to a coordinate point in the print color reproduction area in the CMYK color space is created. 2 color conversion definition creation process,
The second color conversion definition creation process is
On the gray axis, the value of K obtained by the K plate constraint condition of printing is adopted, and the WMRY plane, WYGGCW, surrounded by ridge lines sequentially connecting W-M-R-Y-W For the WYGC plane surrounded by the sequentially connecting ridge lines and the WCBM plane surrounded by the ridge lines sequentially connecting W-C-B-M-W, a value of K ≦ 0 is used, and RK is connected. For the RK ridgeline, the GK ridgeline connecting G-K, and the BK ridgeline connecting BK, by adopting a value of K ≧ 0, the color reproduction region of the second device on the gray axis, A K value defining process for defining a value of K for each point on the WMRY surface, the WYGC surface, the WCBM surface, the RK ridgeline, the GK ridgeline, and the BK ridgeline;
By the interpolation operation using the K values defined for the respective points on the gray axis, the WMRY plane, the WYGC plane, the WCBM plane, the RK ridgeline, the GK ridgeline, and the BK ridgeline as the boundary condition, the second A K value calculation process for obtaining a K value of each point excluding each point where the K value is defined in the K value definition process in the entire area including the inside of the color reproduction region of the device;
The print profile is referred to using the K value over the entire color reproduction region of the second device, which is composed of the K value defined in the K value defining process and the K value calculated in the K value calculating process, as a constraint. And a K value constraint condition utilization process for creating a second color conversion definition over the entire color reproduction region.

  Here, the two-stage color conversion definition (the first color conversion definition and the second color conversion definition) is in the process of creating the color conversion definition, and finally the two-stage color conversion definitions are combined. One color conversion definition may be used.

  In the method proposed in the above-mentioned Japanese Patent Application No. 2004-075544, the boundary condition (or sample point) for obtaining the K value for each point in the entire color reproduction region by interpolation calculation is shown on the gray axis and each ridge line. Since only the points are used, as a result of the interpolation operation, K> 0 in an area on the WMRY plane, the WYGC plane, the WCBM plane, or in the vicinity of those planes in the color reproduction area and in the vicinity of the W point. As a result, there is a problem that a high brightness color may not be reproduced in printing. In the case of the method proposed in Patent Document 5, the same problem arises because the data for the entire color reproduction region is obtained by interpolation based on the data on the gray axis, each ridge line and diagonal line.

  On the other hand, the color conversion definition creation method of the present invention assigns a value of K ≦ 0 to each point on the WMRY surface, WYGC surface, and WCBM surface, and performs an interpolation operation using these values as boundary conditions. For this reason, a color conversion definition that can reproduce high-brightness colors "cleanly" on printing is created, and the resistance to the K plate constraint condition is remarkably enhanced.

Here, in the color conversion definition creating method of the present invention, the K value definition process is performed for each point on the WMRY plane, the WYGC plane, and the WCBM plane.
Chroma = Max (R, G, B) −Min (R, G, B)
However, Max (R, G, B) is the maximum value of the R, G, B values at that point,
Min (R, G, B) is the minimum value of the R, G, B values at that point.
Represents.
It is preferable that K = 0 when K is the maximum value and that K be a negative value having a large absolute value as Chroma deviates from the maximum value.

  By doing so, a value of K ≦ 0 is surely assigned to the region within the color reproduction region and close to the W point on the surface of the color reproduction region by interpolation, and further, R, G, B, C, By assigning K = 0 to each vertex of M and Y, continuity with K> 0 is secured in a region from each vertex of R, G, B, C, M, and Y toward K point.

  Further, in the color conversion definition creating method of the present invention, the K value calculation process is performed on a gray axis more than each point on the WMRY plane, WYGC plane, WCBM plane, RK ridgeline, GK ridgeline, and BK ridgeline. Each of the above points excluding each point in which the K value is defined in the K value defining process in the entire region including the inside of the color reproduction region of the second device by interpolation calculation with a strong weight applied to each of the above points. It is preferable to be a process of obtaining the K value of the point.

  In this way, interpolation is performed with a higher weight on each point on the gray axis than on each point on the WMRY plane, WYGC plane, WCBM plane, RK ridgeline, GK ridgeline, and BK ridgeline. By doing so, not only on the gray axis but also in the vicinity of the gray axis, the K plate constraint condition is observed, and the gray axis 'shift' between the actual first printer and the virtual second printer. Even if there is, the K plate constraint condition is maintained as it is even on the gray axis of the actual first printer.

In the color conversion definition creating method according to the present invention, the profile creating process may be configured such that each vertex of W, C, M, Y, R, G, and B of the color reproduction region of the second device is used as a color reproduction region for printing. Match the corresponding vertices of W, C, M, Y, R, G, and B, and connect the vertices of W, C, M, Y, R, G, and B in the color reproduction area of the second device. The ridgeline is made to coincide with the corresponding ridgeline in the color reproduction area of the print, and the K maximum value _Kmax of the K plate constraint for printing is adopted for the K vertex of the color reproduction area of the second device (C, M , Y, K) = (100, 100, 100, K _max ) and between the vertices R, G, B and K of the color reproduction region of the second device are R, G, When starting from each vertex of B, up to a predetermined K value K _{param in} the middle (where K _param <K _max ) (C, M, Y, K) = (0, 100, 100, 100), (C, M, Y, K) = (100, 0, 100, 100), (C, M, Y, K) = Trace each ridge line toward each vertex of (100, 100, 0, 100) and, after reaching the value K _param , is the vertex of K away from each ridge line (C, M, Y, K) = (100 , 100, 100, K _max ), it is preferable to include a color reproduction area defining process for defining a color reproduction area of the second device by constructing RK edge lines, GK edge lines, and BK edge lines.

  In defining the color reproduction area of the second device, ridge lines other than the ridge lines from R, G, B to K faithfully trace the color reproduction area of printing, and the ridge lines from R, G, B to K are By “successfully” absorbing the contradiction of the difference in number as described above, it is possible to define a color reproduction region that eliminates the contradiction and substantially matches the color reproduction region of printing.

Here, by _setting K _param <K _max , it is possible to prevent the gradation of the K plate from being inverted near the gray axis compared to the gray axis. From this, the gray axes of the C, M, and Y plates Inversion of gradation in the vicinity is also suppressed.

Further, when the profile creation process includes the color reproduction area definition process, the K value definition process is performed on each of the RK ridgeline, the GK ridgeline, and the BK ridgeline between K _param and K _max. The point is preferably a process of assigning a value of K obtained by interpolation calculation.

If a value of K is assigned by interpolation for each point between K _param and K _max , the inversion of the gradation of the K plate can be prevented more reliably.

Alternatively, when the profile creation process includes the color reproduction region definition process, the K value definition process is performed on each of the RK ridgeline, the GK ridgeline, and the BK ridgeline between K _param and K _max. It is also a preferable aspect that a point is a process of assigning a K value that is prorated between a maximum value and a minimum value that can be taken as the K value of the point at a predetermined ratio.

For each point between K _param and K _max , if the minimum value that can be taken as the K value at that point is adopted, the inversion of the gradation of the K plate can be prevented more reliably, while the K at that point When the maximum value that can be taken is adopted, the total amount of ink during printing can be reduced. Therefore, by assigning a value of K that is apportioned between a maximum value and a minimum value that can be taken as the value of K at that point at a predetermined ratio, it is possible to achieve both merits at a high level.

Further, when the profile creation process includes the color reproduction region definition process, the profile creation process further includes:
When a plurality of points are defined at equal intervals on any one side that defines the color reproduction region of the second device in the second RGB color space, and the plurality of points are mapped to the common color space, A plurality of points mapped on the common color space are on a ridge line corresponding to the one side of the ridge lines defining the color reproduction area of the second device defined in the color reproduction area defining process; and A ridge line that associates a coordinate point in the second RGB color space with a coordinate point in the common color space for each ridge line in the color reproduction region of the second device so that the intervals along the ridge line are arranged at equal intervals. Edge line profile creation process to create a profile,
When a plurality of points are defined at equal intervals on the gray axis connecting the two vertices W and K of the color reproduction area of the second device in the second RGB color space, and these points are mapped onto the common color space In addition, a plurality of points mapped on the common color space are on the gray axis connecting the two vertices W and K defined in the color reproduction area defining process, and the intervals along the gray axis are equal intervals. A gray axis profile for creating a gray axis profile in which the coordinate points in the second RGB color space and the coordinate points in the common color space are associated with each other with respect to the gray axis of the color reproduction region of the second device Creation process,
Surfaces other than the ridgeline in the color reproduction area of the second device by interpolation using the ridgeline profile created in the ridgeline profile creation process as the boundary condition and the gray axis profile created in the gray axis profile creation process as the boundary condition And a profile calculation process for calculating an internal profile other than the gray axis.

  As described above, a plurality of points on the ridge line and a plurality of points on the gray axis are equally spaced by the ridge line profile creating process and the gray axis profile creating process (here, the equidistant property in the above sense is expressed as “RGB value”). The coordinates on the edge of the common color space with respect to the coordinates on the edge of the second RGB space so that the coordinates on the gray axis are determined and the coordinates on the gray axis are determined. By calculating the surface profile other than the ridge line of the device color reproduction region and the internal profile other than the gray axis, the compatibility with the gamut mapping method disclosed in the above-mentioned Patent Document 2 is enhanced, and highly accurate gamut mapping is performed. It is.

In addition, the profile creation method of the present invention that achieves the above-described object provides a CMYK color for printing using coordinate points in a color reproduction region of a device in an RGB color space depending on the device that mediates between the image and the image data. In a profile creation method for creating a link profile for conversion to a coordinate point in a color reproduction area of printing in space,
On the gray axis, the value of K obtained by the K plate constraint condition of printing is adopted, and the WMRY plane, WYGGCW, surrounded by ridge lines sequentially connecting W-M-R-Y-W For the WYGC plane surrounded by the sequentially connecting ridge lines and the WCBM plane surrounded by the ridge lines sequentially connecting W-C-B-M-W, a value of K ≦ 0 is used, and RK is connected. For the RK ridge line, the GK ridge line connecting G-K, and the BK ridge line connecting BK, by adopting a value of K ≧ 0, the color reproduction region of the above device on the gray axis, on the WMRY plane A K value defining process for defining a value of K for each point on the WYGC plane, WCBM plane, RK ridgeline, GK ridgeline, and BK ridgeline;
On the gray axis, the WMRY plane, the WYGC plane, the WCBM plane, the RK ridgeline, the GK ridgeline, and the BK ridgeline, the interpolation operation using the K values defined for each point as a boundary condition is performed. A K value calculation process for obtaining a K value of each point excluding each point where the K value is defined in the K value definition process in the entire area including the inside of the color reproduction region;
By referring to the print profile using the K value defined in the K value definition process and the K value calculated in the K value calculation process over the entire color reproduction region of the device as a constraint. And a K value constraint condition utilization process for creating the link profile over the entire color reproduction region.

  According to the profile creation method of the present invention, a K value of K ≦ 0 is assigned to each point on the WMRY plane, the WYGC plane, and the WCBM plane, and interpolation is performed using this as a boundary condition. Above, a color conversion definition that can reproduce high-brightness colors "cleanly" is created, and the resistance to K plate constraint conditions is significantly increased.

The color conversion definition creating apparatus of the present invention that achieves the above object is an apparatus that implements the above-described color conversion definition creating method of the present invention. That is, the color conversion definition creating apparatus of the present invention calculates the coordinate points in the color reproduction region of the first device in the first RGB color space depending on the first device that mediates between the image and the image data. In a color conversion definition creating apparatus for creating a color conversion definition for converting to a coordinate point in a printing color reproduction area in a CMYK color space for printing,
Between a second RGB color space depending on a virtual second device that mediates between an image and image data, having a color reproduction area that follows the color reproduction area of printing, and a predetermined common color space A profile creation unit for creating a virtual device profile;
Using the device profile of the first device and the virtual device profile created by the profile creation unit, the coordinate point in the color reproduction area of the first device in the first RGB color space is determined as the second RGB. A first color conversion definition creating unit for creating a first color conversion definition for converting to a coordinate point in the color reproduction region of the second device in the color space;
A second color conversion definition for converting a coordinate point in the color reproduction area of the second device in the second RGB color space to a coordinate point in the print color reproduction area in the CMYK color space is created. 2 color conversion definition creation section,
The second color conversion definition creation unit
On the gray axis, the value of K obtained by the K plate constraint condition of printing is adopted, and the WMRY plane, WYGGCW, surrounded by ridge lines sequentially connecting W-M-R-Y-W For the WYGC plane surrounded by the sequentially connecting ridge lines and the WCBM plane surrounded by the ridge lines sequentially connecting W-C-B-M-W, a value of K ≦ 0 is used, and RK is connected. For the RK ridgeline, the GK ridgeline connecting G-K, and the BK ridgeline connecting BK, by adopting a value of K ≧ 0, the color reproduction region of the second device on the gray axis, A K value definition unit that defines a value of K for each point on the WMRY plane, the WYGC plane, the WCBM plane, the RK ridgeline, the GK ridgeline, and the BK ridgeline;
A second value is obtained by an interpolation operation using the K value defined for each point on the gray axis, the WMRY surface, the WYGC surface, the WCBM surface, the RK edge line, the GK edge line, and the BK edge line as a boundary condition. A K value calculation unit for obtaining a K value of each point excluding each point where the K value is defined in the K value definition unit in the entire region including the inside of the device color reproduction region;
The print profile is referred to using the K value over the entire color reproduction region of the second device, which is composed of the K value defined by the K value definition unit and the K value calculated by the K value calculation unit, as a constraint. Thus, a K value constraint condition utilization unit for creating a second color conversion definition over the entire color reproduction region is provided.

  Note that the color conversion definition creating apparatus of the present invention includes all modes for realizing the above-described various modes of the color conversion definition creating method of the present invention.

Moreover, the profile creation apparatus of the present invention that achieves the above object is an apparatus that implements the above-described profile creation method of the present invention. That is, the profile creation apparatus according to the present invention uses the coordinate points in the color reproduction region of the device in the RGB color space depending on the device that mediates between the image and the image data as the print color in the CMYK color space for printing. In a profile creation device that creates a link profile for conversion to a coordinate point in the reproduction area,
On the gray axis, the value of K obtained by the K plate constraint condition of printing is adopted, and the WMRY plane, WYGGCW, surrounded by ridge lines sequentially connecting W-M-R-Y-W For the WYGC plane surrounded by the sequentially connecting ridge lines and the WCBM plane surrounded by the ridge lines sequentially connecting W-C-B-M-W, a value of K ≦ 0 is used, and RK is connected. For the RK ridge line, the GK ridge line connecting G-K, and the BK ridge line connecting BK, by adopting a value of K ≧ 0, the color reproduction region of the above device on the gray axis, on the WMRY plane A K value defining unit that defines a value of K for each point on the WYGC plane, the WCBM plane, the RK ridgeline, the GK ridgeline, and the BK ridgeline;
On the gray axis, the WMRY plane, the WYGC plane, the WCBM plane, the RK ridgeline, the GK ridgeline, and the BK ridgeline, the interpolation operation using the K values defined for each point as a boundary condition is performed. A K value calculation unit for obtaining a K value of each point excluding each point where the K value is defined in the K value definition unit in the entire region including the inside of the color reproduction region;
By referring to the print profile using the K value defined by the K value definition unit and the K value calculated by the K value calculation unit over the entire color reproduction region of the device as a constraint. And a K-value constraint condition utilization unit that creates the link profile over the entire color reproduction region.

The profile creation device of the present invention includes all modes for realizing various modes of the profile creation method of the present invention.
The color conversion definition creating program of the present invention that achieves the above object is a program that causes an information processing apparatus such as a computer to operate as the above-described color conversion definition creating apparatus of the present invention. That is, the color conversion definition creating program of the present invention is executed in an information processing apparatus in which the program is executed, and the information processing apparatus is dependent on a first device that mediates between an image and image data. Creating a color conversion definition for creating a color conversion definition for converting a coordinate point in the color reproduction area of the first device in the RGB color space to a coordinate point in the color reproduction area of the print in the CMYK color space for printing In the color conversion definition creation program that operates as a device,
The information processing apparatus is
Between a second RGB color space depending on a virtual second device that mediates between an image and image data, having a color reproduction area that follows the color reproduction area of printing, and a predetermined common color space A profile creation unit for creating a virtual device profile;
Using the device profile of the first device and the virtual device profile created by the profile creation unit, the coordinate point in the color reproduction area of the first device in the first RGB color space is determined as the second RGB. A first color conversion definition creating unit for creating a first color conversion definition for converting to a coordinate point in the color reproduction region of the second device in the color space;
A second color conversion definition for converting a coordinate point in the color reproduction area of the second device in the second RGB color space to a coordinate point in the print color reproduction area in the CMYK color space is created. 2 color conversion definition creation section,
The second color conversion definition creation unit
On the gray axis, the value of K obtained by the K plate constraint condition of printing is adopted, and the WMRY plane, WYGGCW, surrounded by ridge lines sequentially connecting W-M-R-Y-W For the WYGC plane surrounded by the sequentially connecting ridge lines and the WCBM plane surrounded by the ridge lines sequentially connecting W-C-B-M-W, a value of K ≦ 0 is used, and RK is connected. For the RK ridgeline, the GK ridgeline connecting G-K, and the BK ridgeline connecting BK, by adopting a value of K ≧ 0, the color reproduction region of the second device on the gray axis, A K value definition unit that defines a value of K for each point on the WMRY plane, the WYGC plane, the WCBM plane, the RK ridgeline, the GK ridgeline, and the BK ridgeline;
A second value is obtained by an interpolation operation using the K value defined for each point on the gray axis, the WMRY surface, the WYGC surface, the WCBM surface, the RK edge line, the GK edge line, and the BK edge line as a boundary condition. A K value calculation unit for obtaining a K value of each point excluding each point where the K value is defined in the K value definition unit in the entire region including the inside of the device color reproduction region;
The print profile is referred to using the K value over the entire color reproduction region of the second device, which is composed of the K value defined by the K value definition unit and the K value calculated by the K value calculation unit, as a constraint. Thus, the apparatus is operated as a color conversion definition creation device including a K value constraint condition utilization unit that creates a second color conversion definition over the entire color reproduction region.

  The color conversion definition creating program of the present invention includes all modes for realizing various modes of the color conversion definition creating method and the color conversion definition creating apparatus of the present invention.

Furthermore, the profile creation program of the present invention that achieves the above object is a program that causes an information processing apparatus such as a computer to operate as the above-described profile creation apparatus of the present invention. In other words, the profile creation program of the present invention is executed in an information processing apparatus in which the program is executed, and the information processing apparatus is connected to the device in the RGB color space depending on the device that mediates between the image and the image data. In a profile creation program that operates as a profile creation device for creating a link profile for converting a coordinate point in a color reproduction area to a coordinate point in a print color reproduction area in a CMYK color space for printing,
The information processing apparatus is
On the gray axis, the value of K obtained by the K plate constraint condition of printing is adopted, and the WMRY plane, WYGGCW, surrounded by ridge lines sequentially connecting W-M-R-Y-W For the WYGC plane surrounded by the sequentially connecting ridge lines and the WCBM plane surrounded by the ridge lines sequentially connecting W-C-B-M-W, a value of K ≦ 0 is used, and RK is connected. For the RK ridge line, the GK ridge line connecting G-K, and the BK ridge line connecting BK, by adopting a value of K ≧ 0, the color reproduction region of the above device on the gray axis, on the WMRY plane A K value defining unit that defines a value of K for each point on the WYGC plane, the WCBM plane, the RK ridgeline, the GK ridgeline, and the BK ridgeline;
On the gray axis, the WMRY plane, the WYGC plane, the WCBM plane, the RK ridgeline, the GK ridgeline, and the BK ridgeline, the interpolation operation using the K values defined for each point as a boundary condition is performed. A K value calculation unit for obtaining a K value of each point excluding each point where the K value is defined in the K value definition unit in the entire region including the inside of the color reproduction region;
By referring to the print profile using the K value defined by the K value definition unit and the K value calculated by the K value calculation unit over the entire color reproduction region of the device as a constraint. The apparatus is operated as a profile creation apparatus including a K value constraint condition utilization unit that creates the link profile over the entire color reproduction region.

  The profile creation program of the present invention includes all modes for realizing various modes of the profile creation method and profile creation apparatus of the present invention.

  As described above, according to the present invention, the resistance to the K plate constraint condition is improved, and a high brightness color can be reproduced "cleanly" on printing.

  Hereinafter, embodiments of the present invention will be described.

  FIG. 1 is a diagram showing a system in which a color conversion definition created according to the present invention is adopted. Here, first, the positioning of the present invention will be described with reference to FIG.

  RGB data representing an image is input to the printer 11, and the printer 11 outputs a print image 11a based on the input RGB data. Here, it is required to create a print image 12a that reproduces the same color as that of the print image 11a. In this case, the RGB data is input to the color conversion device 10. The details of the color conversion device 10 will be described later. In this color conversion device 10, RGB data (RGB data suitable for the printer 11) created in advance according to an embodiment of the present invention described later is input. A first color conversion definition for converting to RGB data suitable for a virtual proof output printer (proofer) 14 and the RGB data converted using the first color conversion definition for printing. A second color conversion definition for conversion into CMYK data is stored, and the color conversion apparatus 10 performs color conversion based on the first color conversion definition (referred to as gamut mapping), and further includes a second color conversion definition. By performing color conversion based on the color conversion definition (referred to as color matching), RGB data on the input side is converted into CMYK data for printing. Here, for convenience of explanation, the color conversion (gamut mapping) based on the first color conversion definition and the color conversion (color matching) based on the second color conversion definition are described separately. When actually converting RGB data into CMYK data for printing, in order to perform color conversion at high speed, one color conversion definition is obtained by combining the first color conversion definition and the second color conversion definition. , And RGB data on the input side is converted into CMYK data for printing based on the combined color conversion definition.

  The CMYK data generated in this way is sent to the printing system 12. In the printing system 12, for example, a film original is created based on the CMYK data, a printing plate is created based on the film original, printing is performed, and a print image 12a is created.

  Here, when creating a print image using the printing system 12, since this system 12 is a large-scale system, the print image 12a is printed before printing by the printing system 12 to obtain the print image 12a. Prior confirmation may be performed in order to predict what kind of image 12a will be finished. In this case, a proofer that can print out a proof image that highly mimics the color of the print image 12a is generally used to perform advance confirmation, and the proof image 12a is completed in advance. After being confirmed, the print image 12a is created as described above.

  On the other hand, the prior confirmation is completed by the printer 11, and in the embodiment described later, the color reproduction area is sufficiently equal to the color reproduction area of the printing system 12 instead of an actual proofer used for prior confirmation of the print image 12a. A matched virtual proofer 14 is assumed. The first color conversion definition described above is for converting input RGB data into RGB data for the virtual proofer 14. The virtual proofer 14 is defined by a color reproduction characteristic (proofer profile) created so that the color reproduction area sufficiently matches the color reproduction area of the printing system 12. A method for creating this proofer profile will be described later.

  In the following description, the RGB data on the input side may be referred to as input RGB data or input RGB, and the RGB data for the virtual proofer 14 may be referred to as “dummy RGB data” or “dummy RGB” in order to distinguish each other.

  Here, if the input RGB data is “correctly” converted to CMYK data by the color conversion device 10, the print image 12 a becomes an image having the same impression color as the print image 11 a, and prior confirmation is performed by the printer 11. I can finish it.

  In order for the input RGB data to be “correctly” converted to CMYK data by the color conversion device 10, “successfully” based on the difference between the color reproduction characteristics (printer profile) of the printer 11 and the color reproduction characteristics (print profile) of the printing system 12. 'It is necessary that the color conversion has been performed, and that is not enough, and the CMYK data obtained by the color conversion needs to be data (suitable for printing) suitable for the printing system 12.

  Based on the color reproduction characteristics (printer profile) of the printer 11 and the color reproduction characteristics (printing profile) of the printing system 12, the RGB data is converted into CMYK data representing the same colorimetrically as the RGB data. When creating a color conversion definition, RGB data has three variables R, G, and B, while CMYK data has four variables C, M, Y, and K. There are a lot of CMYK data representing the same colorimetrically with respect to RGB data, and there is a problem that it cannot be uniquely converted, or any one of a large number of CMYK data that is the same colorimetrically is selected. However, there is a problem that CMYK data having print suitability is not always selected.

  On the other hand, the RGB data is converted into data representing CMY (CMY data) such as a block CMY, and the CMY data is input to a color conversion apparatus adjusted by an expert so as to be compatible with the printing system 12 to be CMYK data. Can be obtained CMYK data having printability for the printing system 12, but in this case, it is not always converted to CMYK data representing the same color as the original RGB data, and the color adjustment is performed. There is a problem that it is converted into CMYK data representing a color in which the “preference” of the skilled worker or the printing company, etc., has entered.

  Further, as described above, the color reproduction characteristic (printer profile) of the printer 11 and the color reproduction characteristic (printing profile) of the printing system 12 are different, and there is a problem that it is necessary to absorb the difference 'good'.

  In the following, printer RGB data (coordinate points in the RGB color space) that is set in the color conversion device 10 of FIG. Even if the color reproduction characteristic (printer profile) and the color reproduction characteristic (printing profile) of the printing system 12 are different, the color of the printed image 11a obtained when the printer 11 prints out based on the RGB data is different. A color conversion definition that can be converted into CMYK data (coordinate points in the CMYK color space) that can create a print image with a highly matched impression (first color conversion definition and block shown in FIG. 1) The method for creating the second color conversion definition will be described.

  FIG. 2 is an external perspective view of a personal computer constituting one embodiment of the color conversion definition creating apparatus of the present invention, and FIG. 3 is a hardware configuration diagram of the personal computer. The color conversion definition creating apparatus of this embodiment includes an embodiment of the profile creating apparatus of the present invention.

  Here, the color conversion of the present invention is performed by the hardware and OS (operating system) of the personal computer 20 and the color conversion definition creation program (including the profile creation program) installed and executed in the personal computer 20. One embodiment of the definition creation device (including one embodiment of the profile creation device of the present invention) is configured.

  Here, the color conversion apparatus 10 shown in FIG. 1 can also be realized by a personal computer. In this embodiment, the personal computer 20 shown in FIGS. 2 and 3 constituting the color conversion definition creation apparatus of this embodiment is It is assumed that the hardware also serves as the color conversion device 10 shown in FIG. However, the personal computer constituting the color conversion definition creating apparatus is a personal computer different from the personal computer constituting the color conversion apparatus 10 shown in FIG. 1, and the color conversion definition created by the color conversion definition creating apparatus is used. May be installed in the color conversion apparatus 10 of FIG.

  In the following, first, the hardware of the personal computer shown in FIGS. 2 and 3 will be described, and then an embodiment of the color conversion definition creation method of the present invention performed using this personal computer will be described.

  As shown in FIG. 2, the personal computer 20 includes a main body device 21, an image display device 22 that displays an image on a display screen 22 a in accordance with an instruction from the main body device 21, and the main body device 21. By designating an arbitrary position on the display screen 22a and a keyboard 23 for inputting various information according to key operations, an instruction according to, for example, an icon or the like displayed at that position at the time of designation is input. A mouse 24 is provided. The main unit 21 has an MO loading port 21a for loading a magneto-optical disk (MO) and a CD / DVD loading port 21b for loading a CD or DVD in appearance.

  As shown in FIG. 3, the main body device 21 includes a CPU 211 that executes various programs, a main memory 212 that is read out by a program stored in the hard disk device 213 and developed for execution by the CPU 211, and various programs. And a hard disk device 213 storing data and the like, an MO drive 214 loaded with a magneto-optical disk (MO) 100 and accessing the loaded magneto-optical disk 100, a CD or a DVD (represented by the CD-ROM 110 here). A CD / DVD drive 215 that is loaded and accesses the loaded CD-ROM 110, here, the personal computer 20 also serves as the color conversion device 10 of FIG. 1 and receives RGB data from the outside. Interface 216 and printing system 12 An output interface 217 for sending CMYK data is built in, and these various elements and the image display device 22, keyboard 23, and mouse 24 shown in FIG. 2 are connected to each other via a bus 25. .

  Here, the CD-ROM 110 stores a color conversion definition creation program for operating the personal computer 20 as a color conversion definition creation device. The CD-ROM 110 is loaded into the CD / DVD drive 215 and the CD-ROM 110 is loaded. The color conversion definition creation program stored in the ROM 110 is uploaded to the personal computer 20 and stored in the hard disk device 213.

  FIG. 4 is a flowchart showing an embodiment of the color conversion definition creating method of the present invention.

This color conversion definition creation method performs color reproduction of the first device in the input RGB color space that depends on the first device (here, the printer 11 shown in FIG. 1) that mediates between the image and the image data. A color conversion definition creating method for creating a color conversion definition for converting a coordinate point in an area to a coordinate point in a printing color reproduction area in the CMYK color space for printing of the printing system 12 shown in FIG. A predetermined common with a dummyRGB color space that depends on a virtual second device (for example, the proofer 14 shown in FIG. 1) that mediates between an image and image data, having a color reproduction area that follows the color reproduction area of printing. a profile creating step for creating a virtual device profile (proofer profile) between the color space (here L ^* a ^* b ^* color space) (step (a)), the first device The first device (printer 11) in the input RGB color space using the device profile (printer profile) of the printer (printer 11) and the virtual device profile (proofer profile) created in the profile creation process of step (A). The first color conversion definition for creating the first color conversion definition for converting the coordinate point in the color reproduction area of (2) into the coordinate point in the color reproduction area of the second device (proofer 14) in the dummy RGB color space. The coordinate point in the color reproduction area of the second device (proofer (B)) in the creation process (step (B)) and the dummy RGB color space is converted to the coordinate point in the color reproduction area of printing in the CMYK color space. A second color conversion definition creation process (step (C)) for creating a second color conversion definition for the purpose.

  Details of the color conversion definition creation method shown in FIG. 4 will be described later.

  FIG. 5 is a flowchart showing a detailed flow of the profile creation process (step (A)) in the color conversion definition creation method shown in FIG.

The profile creation process shown in FIG. 5 is based on the RGB color depending on the virtual device (the proofer 14 in FIG. 1) that has a color reproduction area that traces the color reproduction area of printing and mediates between the image and the image data. A profile creation method for creating a virtual device profile (proofer profile) between a space (the above dummy RGB color space) and a predetermined common color space (L ^* a ^* b ^* color space in the present embodiment), The color reproduction region defining process (step (a1)), the edge line profile creating process (step (a2)), the gray axis profile creating process (step a3)), and the profile calculating process (step (a4)).

Here, in the color reproduction area defining process in step (a1), the color reproduction areas for printing the vertices of W, C, M, Y, R, G, and B of the color reproduction area of the second device (proofer 14). Are matched with the corresponding vertices of W, C, M, Y, R, G, and B, and W, C, M, Y, R, G, and B of the color reproduction region of the second device (proofer 14). The ridge line connecting the vertices of each of the two colors coincides with the corresponding ridge line of the print color reproduction area, and the K value vertex K of the print K plate constraint condition for the K vertex of the color reproduction area of the second device (proofer 14). point of adopting the _{max (C, M, Y,} K) = (100,100,100, K max) each vertex of R, G, B of the color reproduction area of the second device with match the (proofer 14) Between K and the vertex of K, when starting from each vertex of R, G, B, a predetermined K in the middle The value K _param (where, K _param <K _max) to each, (C, M, Y, K) = (0,100,100,100), (C, M, Y, K) = (100, 0,100,100), (C, M, Y, K) = (100,100,0,100), tracing each ridge line toward each vertex, and after reaching the value K _param , away from each ridge line By constructing a ridge line that reaches (C, M, Y, K) = (100, 100, 100, K _max ), which is the vertex of the second device, the color reproduction region of the second device (proofer 14) is defined.

Further, in the ridge line profile creation process in step (a2), a plurality of points are set at equal intervals on any one side that defines the color reproduction region of the second device (proofer 14) in the above-described dummy RGB color space. Thus, when these multiple points are mapped to a common color space (here, L ^* a ^* b ^* color space), the multiple points mapped on the common color space are the color reproduction area defining process in step (a1). The ridge lines that define the color reproduction region of the second device (proofer 14) defined in (1) are on the ridge line corresponding to the one side of the ridge line, and the intervals along the ridge line are arranged at equal intervals. In addition, a ridge line profile in which coordinate points in the dummy RGB color space and coordinate points in the common color space are associated with each ridge line in the color reproduction region of the second device (proofer 14) is created.

  Furthermore, in the gray axis profile creation process in step (a3), a plurality of equal intervals are formed on the gray axis connecting the two vertices W and K of the color reproduction region of the second device (proofer 14) in the above-described dummy RGB color space. When a plurality of points are mapped onto the common color space by defining points, the plurality of points mapped onto the common color space are defined as W and K defined in the color reproduction region definition process in step (a1). Coordinates in the dummyRGB color space relating to the gray axis of the color reproduction region of the second device (proofer 14) so that the intervals along the gray axis are evenly spaced on the gray axis connecting the two vertices. A gray axis profile is created in which the points are associated with coordinate points in the common color space.

  Furthermore, in the profile calculation process in step (a4), the edge profile created in the edge profile creation process in step (a2) is used as a boundary condition, and the gray axis profile created in the gray axis profile creation process in step (a3). As a boundary condition, a profile other than the edge of the color reproduction region of the second device (proofer 14) and an internal profile other than the gray axis are calculated.

  Detailed description of the first profile creation method shown in FIG. 5 (the profile creation process in step (A) in FIG. 4) will be given later.

  FIG. 6 is a flowchart showing an embodiment of the profile creation method of the present invention. The flowchart of FIG. 6 is a flowchart of an embodiment of the profile creation method of the present invention when implemented independently, and in the embodiment of the color conversion definition creation method shown in FIG. This also corresponds to the detailed flow of the second color conversion definition creation process.

  The profile creation method (second color conversion definition creation process in step (C) of FIG. 4) as an embodiment shown in FIG. 6 is a device that mediates between images (the proofer 14 of FIG. 1). To convert the coordinate point in the color reproduction area of the device (proofer 14) in the RGB color space that depends on the above (dummy RGB color space) to the coordinate point in the print color reproduction area in the CMYK color space for printing A profile creation method for creating a link profile of a K value, comprising a K value definition process (step (c1)), a K value calculation process (step (c2)), and a K value constraint condition utilization process (step (c3)). Has been.

  Here, in the K value definition process of step (c1), the value of K obtained by the K plate constraint condition for printing is adopted on the gray axis, and is surrounded by ridge lines that sequentially connect W-M-R-Y-W. K ≦ 0 for a WMRY plane, a WYGC plane surrounded by a ridge line sequentially connecting W-Y-G-C-W, and a WCBM plane surrounded by a ridge line sequentially connecting W-C-B-M-W By adopting the value of K, and for the RK ridge line connecting RK, the GK ridge line connecting G-K, and the BK ridge line connecting BK, by adopting the K value of K ≧ 0, the device A value of K is defined for each point on the gray axis, the WMRY plane, the WYGC plane, the WCBM plane, the RK ridgeline, the GK ridgeline, and the BK ridgeline in the color reproduction region of the (proofer 14).

Specifically, in the K value definition process in step (c), for each point on the WMRY surface, the WYGC surface, and the WCBM surface,
Chroma = Max (R, G, B) −Min (R, G, B)
However, Max (R, G, B) is the maximum value of the R, G, B values at that point,
Min (R, G, B) is the minimum value of the R, G, B values at that point.
Represents.
When K = 0, K = 0, and as Chroma deviates from the maximum value, K is assigned a negative value having a large absolute value.

In the K value definition process in step (c1), each point between K _param and K _max on the RK ridge line, the GK ridge line, and the BK ridge line is obtained by interpolation, and K> 0 Is assigned a value of K.

Alternatively, in the K value defining process in step (c1), each point between K _param and K _max on the RK ridge line, the GK ridge line, and the BK ridge line can be taken as the K value of that point. A value of K that is apportioned between a maximum value and a minimum value at a predetermined ratio may be assigned.

  In the K value calculation process of step (c2), K defined for each point on the gray axis, the WMRY surface, the WYGC surface, the WCBM surface, the RK ridgeline, the GK ridgeline, and the BK ridgeline. As a boundary condition, the points on the gray axis are more strongly weighted than the points on the WMRY plane, WYGC plane, WCBM plane, RK ridgeline, GK ridgeline, and BK ridgeline. Interpolation calculation is performed, and each point where the value of K is defined in the K value definition process (step (c)) in the entire area including the inside of the color reproduction region of the device (proofer 14) is excluded. The value of K for each point is determined.

  Further, in the process of using the K value constraint condition in step (c3), the K value defined in the K value definition process in step (c1) and the K value calculated in the K value calculation process in step (c2) are used. The link profile over the entire color reproduction region is created by referring to the print profile using the K value over the entire color reproduction region of the device (proofer 14) as a constraint.

  A detailed description of the profile creation method shown in FIG. 6 (second color conversion definition creation process in step (C) of FIG. 4) will be given later.

  In this embodiment, the color conversion definition creating method shown in FIG. 4 (including the profile creating method shown in FIG. 6) is applied to the personal computer 20 shown in FIGS. The embodiment is implemented by being installed and executed.

  FIG. 7 is a schematic configuration diagram of an embodiment of a color conversion definition creation program of the present invention.

  The color conversion definition creating program shown in FIG. 7 is stored in the CD-ROM 110 shown in FIG. 3 and is installed in the personal computer 20 shown in FIGS. 2 and 3 from the CD-ROM 110. The first device (printer 11) in the input RGB color space depending on the first device (here, the printer 11 of FIG. 1) that mediates between the personal computer 20 and the image data. Color conversion definition creation that operates as a color conversion definition creation device for creating a color conversion definition for converting the coordinate points in the color reproduction region of () to coordinate points in the print color reproduction region in the CMYK color space for printing It is a program. The color conversion definition creation program 310 includes a profile creation unit 31, a first color conversion definition creation unit 32, and a second color conversion definition creation unit 33.

  These are the profile creation unit 31, the first color conversion definition creation unit 32, and the second color conversion definition creation unit 33. The color conversion definition creation program 30 shown in FIG. When installed in the computer 20 and executed, the personal computer 20 can execute the profile creation process in step (A) and the first color conversion in step (B) of the color conversion definition creation method shown in FIG. This is a program component for executing the definition creating process and the second color conversion definition creating process in step (C). Detailed descriptions of the profile creation unit 31, the first color conversion definition creation unit 32, and the second color conversion definition creation unit 33 will be given later.

  FIG. 8 is a schematic configuration diagram of the profile creation unit 31 which is one program component in the color conversion definition creation program 30 shown in FIG.

  The profile creation unit 31 shown in FIG. 8 includes a color reproduction region definition unit 311, a ridge line profile creation unit 312, a gray axis profile creation unit 313, and a profile calculation unit 314.

  The color reproduction region definition unit 311, the ridge line profile creation unit 312, the gray axis profile creation unit 313, and the profile calculation unit 314 are added to the personal computer 20 shown in FIGS. 2 and 3 by the profile creation unit 31 shown in FIG. When installed and executed, the personal computer 20 has the profile creation process shown in FIG. 5, the color reproduction region definition process in step (a1), the edge profile creation process in step (a2), step ( Each program part that executes the gray axis profile creation process of a3) and the profile calculation process of step (a4), and the profile creation process of step (A) of the color conversion definition creation method of FIG. It is a program part. Detailed descriptions of the color reproduction region definition unit 311, the ridge line profile creation unit 312, the gray axis profile creation unit 313, and the profile calculation unit 314 will be given later.

  FIG. 9 is a schematic configuration diagram of an embodiment of the profile creation program of the present invention. In FIG. 9, the profile creation program 330 is independently stored in the CD-ROM 110. However, the second color conversion definition creation unit 33 of the color conversion definition creation program 30 shown in FIG. 330 has the same configuration.

  The profile creation program 330 shown in FIG. 9 is installed and executed in the personal computer 20 shown in FIGS. 2 and 3, thereby allowing the personal computer 20 to mediate between images and image data (FIG. 1). In order to convert the coordinate point in the color reproduction area of the device in the RGB color space (the above described dummy RGB color space) depending on the proofer 14) to the coordinate point in the printing color reproduction area in the CMYK color space for printing. A profile creation program that operates as a profile creation device that creates a link profile of the link profile, and includes a K value definition unit 331, a K value calculation unit 332, and a K value constraint condition use unit 333.

  These K value definition unit 331, K value calculation unit 332, and K value constraint condition utilization unit 333 are executed by installing the profile creation program 330 shown in FIG. 9 in the personal computer 20 shown in FIGS. 6, the K value definition process in step (c1), the K value calculation process in step (c2), and the K value constraint in step (c3) of the profile creation method shown in FIG. In addition to the program parts that execute the condition use process, the program parts execute the second color conversion definition creating process of step (C) of the color conversion definition creating method of FIG. 4 as a whole. Detailed descriptions of the K value definition unit 331, the K value calculation unit 332, and the K value constraint condition use unit 333 will be given later.

  FIG. 10 is a functional configuration diagram of an embodiment of the color conversion definition creating apparatus of the present invention.

  The color conversion definition creating apparatus 40 shown in FIG. 10 is installed in the personal computer 20 shown in FIGS. 2 and 3 from the CD-ROM 110 shown in FIG. 20 is built. The color conversion definition creating apparatus 40 includes a profile creating unit 41, a first color conversion definition creating unit 42, and a second color conversion definition creating unit 43. These profile creating unit 41, first color The conversion definition creation unit 42 and the second color conversion definition creation unit 43 are respectively the profile creation unit 31, the first conversion definition creation unit 32, and the second color conversion definition creation program 30 shown in FIG. This is a function realized when the color conversion definition creation unit 33 is executed in the personal computer 20. Detailed description will be described later.

  FIG. 11 is a functional configuration diagram of the profile creation unit 41 in the color conversion definition creation device 40 shown in FIG.

  The profile creation unit 41 shown in FIG. 11 includes a color reproduction region definition unit 411, a ridge line profile creation unit 412, a gray axis profile creation unit 413, and a profile calculation unit 414. The color reproduction region definition unit 411, the ridge line profile creation unit 412, the gray axis profile creation unit 413, and the profile calculation unit 414 are respectively the color reproduction region definition unit 311 of the profile creation unit 31 as the program component shown in FIG. This is a function realized when the ridge line profile creation unit 312, the gray axis profile creation unit 313, and the profile calculation unit 314 are executed in the personal computer 20. Detailed explanation will be given later.

  FIG. 12 is a functional configuration diagram of an embodiment of the profile creation device of the present invention.

  The profile creation apparatus 430 shown in FIG. 12 is constructed in the personal computer 20 by installing and executing the profile creation program 330 from the CD-ROM 110 shown in FIG. 9 to the personal computer 20 shown in FIGS. It is what is done. The profile creation device 430 includes a K value definition unit 431, a K value calculation unit 432, and a K value constraint condition utilization unit 433. The K value definition unit 431, the K value calculation unit 432, and the K value constraint condition use unit 433 are respectively the K value definition unit 331, the K value calculation unit 332, and the K value of the profile creation program 330 illustrated in FIG. This is a function realized when the constraint condition utilization unit 333 is executed in the personal computer 20. Further, the second color conversion definition creating unit 43 of the color conversion definition creating apparatus 40 in FIG. 10 has the same configuration as the entire profile creating apparatus 430 shown in FIG.

  Hereinafter, the color conversion definition creation method shown in FIG. 4, the color conversion definition creation program 30 shown in FIG. 7, and the color conversion definition creation apparatus 40 shown in FIG. Step (A) profile creation process (profile creation unit 31 in FIG. 7, profile creation unit 41 in FIG. 10) and first color conversion definition creation process (first in FIG. 7) in step (B) in FIG. Color conversion definition creation unit 32, first color conversion definition creation unit 42 in FIG. 10 and second color conversion definition creation process in step (C) in FIG. 4 (second color conversion definition creation in FIG. 7). The details will be described separately for the section 33 and the second color conversion definition creating section 43) of FIG. In the detailed description, details of the profile creation method of FIG. 6 (the profile creation program 330 of FIG. 9 and the profile creation device 430 of FIG. 12) will also be described.

  In the following description, the color conversion definition creation method and the profile creation method shown in FIGS. However, this is for showing the steps of the explanation (which point is being explained), and the following explanation is common not only for the method but also for the program and the apparatus.

  Here, it is assumed that a printer profile, a printing profile, and a K plate constraint condition described below are obtained as a premise for executing the color conversion definition creating method of FIG.

  FIG. 13 is a conceptual diagram of a printer profile.

The printer profile 51 shown in FIG. 13 is the profile of the printer 11 shown in FIG. 1. The RGB data input to the printer 11 (referred to as input RGB here as described above) and the printer 11 prints it. The color (here, L ^* a ^* b ^* value) on the image 11a to be output is associated. Here, the printer profile 51 is obtained in the form of an LUT (Look Up Table).

The method of creating the printer profile 51 is widely known and will not be described in detail. However, input RGB data in which R, G, and B values are changed in various ways is input to the printer 11 and a large number of color patches are used. A color chart is printed out, and each color patch constituting the color chart is measured with a colorimeter to obtain a colorimetric value (L ^* a ^* b ^* value) of each color patch. Basically, the printer profile 51 is obtained by associating the input RGB values and colorimetric values (L ^* a ^* b ^* values) obtained in this way.

  FIG. 14 is a conceptual diagram of a print profile.

The print profile 52 shown in FIG. 14 is the profile of the printing system 12 shown in FIG. 1, and is printed by the CMYK data input to the printing system 12 and the printing system 12 in the same manner as the printer profile 51 of FIG. The color of the image 12a on the printed matter (here, L ^* a ^* b ^* value) is associated. This print profile 52 is also obtained in the form of an LUT (Look Up Table). The method for creating the print profile 52 is also the same as the method for creating the printer profile 51 in FIG.

Here, the print profile 52 does not match the color reproduction area of the printer profile 51, and generally has a characteristic that the color reproduction area is narrower than the printer profile 51 of a printer that prints a proof sample of printing. Have. 13 is a profile (LUT) in which input RGB three-dimensional data and L ^* a ^* b ^* three-dimensional data are associated with each other. A print profile 52 in FIG. 14 is a CMYK four-dimensional data. This is a profile (LUT) for associating data with three-dimensional data of L ^* a ^* b ^* .

  FIG. 15 is a diagram illustrating the K plate constraint condition.

  In the example shown here, the value of K is defined as a function (CK curve: K = K (C)) with the value of C (cyan) as a variable. For example, as shown in FIG. Is a function in which K <0 in a small region, and K monotonously increases in the entire region. The K plate constraint conditions are determined based on the printing company's concept and preferences for printing, and the gray axis is required to adhere to the K plate constraint conditions faithfully. However, K <0 is not practical, and when the K value finally assigned to each point in the color reproduction region (including the boundary) is K <0, the K value at that point is K = 0 is changed.

  FIG. 16 is a conceptual diagram of a proofer profile that is a profile created in the profile creation process of step (A) of the color conversion definition creation method of FIG. 4 described below.

The proofer profile 53 shown in FIG. 16 is a profile of the proofer 14 which is a virtual printer shown in FIG. 1, and the RGB data input to the proofer 14 (as described above, here the printer shown in FIG. 11 is a LUT for associating the RGB data input to 11 with a color (L ^* a ^* b ^* value) on the image printed by the proofer 14. However, the proofer profile 53 is a profile of the virtual proofer 14, and is logically created as described later.

  FIG. 17 is a conceptual diagram of a link profile, which is a profile created in the second color conversion definition creation process in step (C) of the color conversion definition creation method of FIG. 4 to be described later.

  The link profile 54 shown in FIG. 17 corresponds to the second color conversion definition in the color conversion definition creating method of the present invention, and is a dummy RGB value, that is, a value of RGB data input to the proofer 14 in FIG. , CMYK values, that is, LUTs indicating correspondence relationships with CMYK data values input to the printing system 12 of FIG. The process of creating the link profile 54 is also an embodiment of the profile creation method of the present invention shown in FIG.

  In the profile creation process (step (A)) of the color conversion definition creation method in FIG. 4, the reproduction region definition process (step (a1)), the edge line profile creation process (step (a2)), and the gray axis profile creation shown in FIG. The proofer profile 53 whose concept is shown in FIG. 16 is created by sequentially executing the process (step (a3)) and the profile calculation process (step (a4)). Details will be described below.

  In the color reproduction area definition process (step (a1) in FIG. 5), W (white), C (cyan), M (magenta), Y (yellow), R (red), color reproduction area of the proofer 14 in FIG. For each vertex of G (green) and B (blue), that is, for each vertex excluding K (black), each of W, C, M, Y, R, G, and B corresponding to the print color reproduction region In addition to matching the vertices, the ridge lines connecting the vertices W, C, M, Y, R, G, and B of the color reproduction area of the proofer 14 are made to match the corresponding ridge lines of the print color reproduction area.

In addition, for the vertex of K (black) in the color reproduction region of the proofer 14, the point (C, M, Y, K) = (K) that employs the maximum value K _max of the K plate constraint condition for printing (see FIG. 15). 100, 100, 100, K _max ) and between the vertices R, G, B and K of the color reproduction region of the proofer 14 starts from the vertices R, G, B And (C, M, Y, K) = (0,100,100,100), (C, M, Y, K) = (100,0,100,100), (C, M, Y, K) = (100, 100, 0, 100) is traced along each ridge line toward each vertex, and apart from each ridge line on the way, it is the vertex of K (C, M, Y, K) = (100 , 100, 100, by constructing a ridge leading to K _max), to define a color reproduction area of the proofer 14 . Each position in the L ^* a ^* b ^* color space corresponding to each vertex, each ridge line, and point (C, M, Y, K) of the print color reproduction area can be obtained from the print profile shown in FIG. it can.

  Prior to further explaining this, first, a color reproduction region for printing will be described with reference to the drawings.

FIG. 18 and FIG. 19 are diagrams illustrating a color reproduction area for printing. 18 and 19 are conceptually obtained from the print profile 52 as shown in FIG. 14, but the internal definitions (correspondence between CMYK and L ^* a ^* b ^* ) are different. This type of print profile is required.

FIG. 18 and FIG. 19 both illustrate the color reproduction area of printing in the L ^* a ^* b ^* color space, and each dot is a grid point of the LUT that defines the print profile, and their dot The solid line surrounding the dots represents the ridge line connecting the vertices.

  Each of the color reproduction regions of printing shown in FIGS. 18 and 19 has a “blank” shape. Each vertex of W, C, M, Y, R, G, and B is one each, but in the vicinity of K, (C, M, Y, K) = (100, 100, 100, 100) In addition to vertices, several vertices are dense.

  FIG. 20 is a diagram showing a path followed by each ridge line from each vertex of R, G, B to a vertex of K vertex ((C, M, Y, K) = (100, 100, 100, 100)). It is.

  In this figure, K is a variable of 0 <K <100. On the path from the vertex of R to the vertex of K, there is a reddish vertex of K ((C, M, Y, K) = (0, 100, 100, 100)). There is a G-flavored K vertex ((C, M, Y, K) = (100, 0, 100, 100)) on the path to the vertex of, and the path from the vertex of B to the vertex of K Above, there are B taste K vertices ((C, M, Y, K) = (100, 100, 0, 100)).

  Therefore, here, the color reproduction region of the proofer 14 that “successfully” absorbs the plurality of K vertices is obtained as follows.

  In the color reproduction region definition process (step (a1) in FIG. 5), first, the vertex (white point) of W in the color reproduction region of the proofer 14, that is, (R, G, B) = (255, 255, 255) ( Here, the value 255 is the maximum value of the color reproduction area of the proofer 14 in the dummyRGB color space), and the paper color of the printed material, that is, (C, M, Y, K) = (0, 0, 0, 0). Associate.

The vertex (black point) of K in the color reproduction area of the proofer 14, that is, (R, G, B) = (0, 0, 0) (here, the value 0 is the color reproduction area of the proofer 14 in the dummyRGB color space) The point (C, M, Y, K) = (100,) obtained from the maximum value K _max of K under the K plate constraint condition K = K (C) shown in FIG. 100, 100, K _max ).

Each vertex other than W and K, that is, each vertex of C, M, Y, R, G, and B is each vertex C, M, Y, and R of the print color reproduction area in the L ^* a ^* b ^* color space. , G, and B, and three ridge lines connecting W and C, M, and Y, C, G, and B, M, B, and R, and Y, R, and G, respectively. Nine ridge lines excluding the three ridge lines connecting R, G, B, and K, corresponding to the print color reproduction region in the L ^* a ^* b ^* color space Match each ridgeline.

  FIGS. 21 and 22 are diagrams showing tables defining ridge lines connecting W and C and ridge lines connecting C and G, respectively.

In FIG. 21, (R, G, B) = (255, 255, 255) is associated with the white point of (C, M, Y, K) = (0, 0, 0, 0). The L ^* a ^* b ^* value of this white point is L ^* _0,0,0,0 a ^* _0,0,0,0 b ^* _0,0,0,0 representing the white of the paper.

The table of FIG. 21 is a correspondence table when CMYK values are changed by 10 (here, specifically, the value of C is changed by 10), and (R, G, B) = ( 255 × (9/10), 255, 255) is associated with (C, M, Y, K) = (10, 0, 0, 0). The L ^* a ^* b ^* value at this point is L ^* _10,0,0,0 a ^* _10,0,0,0 b ^* _10,0,0,0 . In the same manner, the tracing is performed by tracing the edge line connecting W and C, and the vertex of C (R, G, B) = (0, 255, 255) is (C, M, Y, K) = (100, 0, 0, 0). The L ^* a ^* b ^* value at that point is L ^* _100,0,0,0 a ^* _100,0,0,0 b ^* _100,0,0,0 .

The association between the values of R, G, B and the values of C, M, Y, K associates the ridge line connecting W and C, and the association between CMYK and L ^* a ^* b ^* is shown in FIG. The print profile 52 is obtained.

Further, in the uppermost stage of FIG. 22, as in the lowermost stage of FIG. 21, the vertex (R, G, B) = (0, 255, 255) of C is the vertex (C, M, Y, K) = (C 100,0,0,0), and the L ^* a ^* b ^* value at that point is L ^* _100,0,0,0 a ^* _100,0,0,0 b ^* _{100,0, There are 0,0} . From the vertex of C toward the vertex of G, the point of (R, G, B) = (0, 255, 255 × (9/10)) is (C, M, Y, K) = (100, 0 , 10, 0), and the L ^* a ^* b ^* value at that point is L ^* _100,0,10,0 a ^* _100,0,10,0 b ^* _100,0,10,0 It is. In the same manner, the ridge line connecting C and G is traced, and the vertex of G (R, G, B) = (0, 255, 0) is the vertex of G (C, M, Y, K) = (100, 0, 100, 0). The L ^* a ^* b ^* values at this point are L ^* _100,0,100,0 a ^* _100,0,100,0 b ^* _100,0,100,0 .

  As shown in the above example, nine ridge lines are defined except for the three ridge lines connecting the vertices of R, G, and B and the vertex of K.

Next, R, G, B vertices and K vertices (C, M, Y, K) defined as above (100, 100, 100, K _max ) and A ridge between is defined.

  FIG. 23 is an explanatory diagram of the definition of the ridge line between the R vertex and the K vertex.

Here, to explain conceptually, starting from the apex of R and going halfway to R-flavored K, (C, M, Y, K) = (0, 100, 100, K _param ) on the way At the point, apart from the ridgeline connecting R and R taste K, the vertex of K defined as described above, that is, (C, M, Y, K) = (100, 100, 100, K _max ) A ridge line leading to is defined.

  FIG. 24 is a diagram illustrating a table in which ridge lines between R vertices and K vertices are defined.

First, at the vertex of R, (R, G, B) = (255, 0, 0) and (C, M, Y, K) = (0, 100, 100, 0) are associated with each other. L ^* a ^* b ^* values of L ^* _{0,100,100,0 are} a ^* _0,100,100,0 b ^* _0,100,100,0 . Tracing the ridgeline from R to R taste K, (R, G, B) = (255 × (9/10), 0,0) is (C, M, Y, K) = (0,100,100) , 10), and the L ^* a ^* b ^* value at that point is L ^* _0,100,100,10 a ^* _0,100,100,10 b ^* _0,100,100,10 . Similarly, until K = K _param is reached, the ridge line from R to R taste K is traced, and (R, G, B) = (R _P , 0, 0) is (C, M, Y, K) = (0, 100, 100, K _param ). The L ^* a ^* b ^* values at this point are L ^* _{0,100,100, kp} a ^* _{0,100,100, kp} b ^* _{0,100,100, kp} .

In FIG. 24, K _param is shown as if it is a multiple of 10, but this is a problem only for the convenience of illustration, and K _param need not be a multiple of 10.

At the point of K = K _param on the ridge line from R to R taste K, this time away from the ridge line, the vertex (C, M, Y, K) of the defined K = (100, 100, 100 , K _max ). The point on the curve away from the ridge line toward the K vertex is obtained by interpolation such as linear interpolation or quasi-Hermitian interpolation. What should be noted here is that dummyRGB and CMYK are associated with each other while they are on the ridge line from R to R taste K, and (R, G, B) = (0, 0, 0) and (C, M, Y, K) = (100, 100, 100, K _max ), and L ^* a ^* b ^* at that point is L ^* _{100,100,100, km} a ^* _{100,100,100, km} b ^* _{It is associated with 100,100,100, km} , but the CMYK values are not associated with each other until the vertex of K is reached after leaving the ridge line from R to R taste K, and R, G, B and L ^* It is a point that a ^* b ^* is directly associated. In this regard, no problem is caused by the processing described later. Rather, in this case, the CMYK values are used to associate the ridge lines (not only the ridge lines from R, G, B to K, but all other ridge lines) with the ridge lines of the color reproduction area of the print. After the edge line is determined in this way, the CMYK value is not necessary once.

FIG. 25 is a diagram showing the relationship between K _max and K _param .

Here, K = K _param when moving away from the ridge line from R to R taste K needs to be smaller than the maximum value K _max of K in the K plate constraint K = K (C) (K _param <K _max ). There is. This is because if K _param is greater than K _max , the K value around the gray axis is greater than the K value on the gray axis. On the other hand, since the black point on the profile of the proofer 14 is fixed at K _max as described above, there is a possibility that the K plate is inverted at the shadow portion of the gray axis of the proofer profile. When the K plate is reversed, the remaining C, M, and Y plates are also reversed. This is highly likely to be unacceptable to the printing operator as described above.

Further, the gray axis of the profile of the printer 11 (printer profile 13 of FIG. 13) as the input device shown in FIG. 1 does not necessarily match the gray axis of the proofer profile that is currently created, and is usually slightly shifted. On the other hand, what should comply with the K plate constraint condition K = K (C) in FIG. 15 is not the virtual proofer 14 but the actual printer 11. Thus not only on the gray axis of the proofer profile that just created, its the periphery of the gray axis it is necessary to comply with the K-plate restraint condition K = K (C), but as mentioned above K _param K _If it is larger than _max , the K plate constraint condition K = K (C) is satisfied on the gray axis of the proofer profile that is being created, but K around the gray axis (for example, on the gray axis of the printer 11) is K. There is a possibility that the plate constraint condition K = K (C) may not be satisfied.

For the above reasons, K _param <K _max is always set here. However, if K _param is set too much smaller than K _max , the dark high-saturation color portion of the color RGB color reproduction region becomes small, so here, for example, as shown in FIG. 24, K _param = A value of K _max −10 is employed.

Here, the ridge line connecting the vertex of R and the vertex of K has been described, but the same applies to the case of generating a ridge line connecting each vertex of G and B and the vertex of K. In that case, the value of K _param may be common to three ridge lines connecting the vertices of R, G, and B and the vertex of K, or may be different values.

  26 to 28 are diagrams showing the color reproduction area of the proofer 14 created by tracing the color reproduction area of printing as described above.

The dots on FIGS. 26 to 28 are the same as the dots on the print profile (LUT) shown in FIG. 19, and the solid line shown in FIGS. 26 to 28 indicates the K plate constraint condition K = K (C). The ridge lines of the color reproduction region of the proofer created as described above when the maximum value K _max of K is K _max = 86, K _max = 64, and K _max = 18, respectively.

As can be seen from FIGS. 26 to 28, the smaller the value of K _max is, the more the print profile and the proofer profile created here do not coincide with each other about K. However, K _max is not the more values the K-plate, a concept such as a print company called not need proofer profile matches the print profile to the part beyond the K _max, and K _max A black spot in the proofer profile is sufficient.

  The above is the processing in the color reproduction region definition process (step (a1)) in FIG.

  Next, processing in the ridge line profile creation process (step (a2)) in FIG. 5 will be described.

Here, a plurality of points defined at equal intervals on a ridge line in the dummy RGB color space (each side of a regular hexahedron in the dummy RGB color space) are equally spaced on the ridge line in the L ^* a ^* b ^* color space. As described above, an equal interval process is performed again to associate the values of dummyRGB with the values of L ^* a ^* b ^* , and a new edge profile is created.

  FIG. 29 is a diagram showing points on the ridge line before re-association, and FIG. 30 is a diagram showing points on the ridge line after re-association.

As shown in FIGS. 21, 22, and 24 (refer to FIG. 21 as a representative here), in the dummyRGB color space, a plurality of points (R, G, B) = (255, 255, 255), ( 255 × (9/10), 255, 255), (255 × (8/10), 255, 255),..., (0, 255, 255) are arranged at equal intervals. Is mapped to the L ^* a ^* b ^* color space (L ^* , a ^* , b ^* ) = (L ^* _0,0,0,0 a ^* _0,0,0,0 b ^* _{0,0,0, 0} ), (L ^* _10,0,0,0a ^* _10,0,0,0b ^* _10,0,0,0 ), (L ^* _20,0,0,0a ^* _{20,0,0 , 0b} ^* _20,0,0,0 ), ..., (L ^* _100,0,0,0a ^* _100,0,0,0b ^* _100,0,0,0 ) The points are not necessarily equally spaced on the L ^* a ^* b ^* color space, and generally vary in spacing as shown in FIG. Therefore, here, a plurality of points on the dummy RGB color space are traced along the same ridge line in the L ^* a ^* b ^* space without deviating from the previous ridge line by the equal interval processing. Redefine the L ^* a ^* b ^* values so that they are sometimes evenly spaced (see FIG. 30). The interval along each ridgeline on the L ^* a ^* b ^* color space may be different for each ridgeline.

  Here, specifically, an algorithm is employed as follows to perform equal interval processing.

  (A) For one ridge line, the color difference ΔE_neighbor, i (i = 1 to n) between adjacent lattice points on the ridge line is calculated.

  (B) Next, a cumulative color difference sequence ΔE_ruiseki, i (i = 0 to n) from one end point of the one ridge line is calculated.

(C) Each cumulative color difference ΔE_ruiseki, i (i = 0 to n) is input, and a one-dimensional lookup table (1DLUT) is generated that outputs the L ^* value of each grid point on that one ridge line.

(D) Similarly, regarding the a ^* value and b ^* value, each accumulated color difference ΔE_ruiseki, i (i = 0 to n) is input, and the a ^* value and b ^* value of each lattice point on the one ridge line are obtained. Each 1DLUT to be output is created, and 1DLUT × 3 is created for each of L ^* , a ^* , b ^* for the accumulated color difference ΔE_ruiseki, i (i = 0 to n).

(E) Output values L ^* , a ^* , and b ^* when a value of ΔE_ruiseki, n × i / n (i = 0 to n) is input to 1DLUT × 3 are set as new lattice points on the one edge line. And

  (F) The above arithmetic processing is performed for each ridgeline.

FIG. 31 is an explanatory diagram of the equalization processing using 1DLUT that inputs the accumulated color difference and outputs the L ^* value in (e) above.

In this 1DLUT, a correspondence relationship between ΔE_ruiseki and L ^* value for each point indicated by a black circle in FIG. 31A is described.

Using this 1DLUT, for example when the seek L ^* values corresponding to ΔE_ruiseki of h point (L ^* _h), sandwich the point h, two points on 1DLUT (here, i point and i + 1 points) L ^* L ^* _h is obtained by reading values (L _i ^* and L _{i + 1} ^* ) and performing linear interpolation between them.

Here, the L ^* value of each point arranged at equal intervals on the axis of ΔE_ruiseki as shown in FIG. Similar calculation processing is performed for the a ^* value and the b ^* value.

  FIG. 32 is a conceptual diagram of lattice points on the ridge line before and after the equal interval processing.

  Before the equal interval processing, as shown in FIG. 32 (A), lattice points are arranged at unequal intervals on one ridge line, and by applying the above-mentioned equal interval processing to this, on that one ridge line, Lattice points arranged at equal intervals with respect to the distance along the ridge line are arranged.

  FIG. 30 described above is a diagram showing each lattice point after the above-described equal interval processing is performed for each ridge line.

  FIG. 33 is a diagram illustrating a table defining ridge lines connecting W and C after the equal interval processing.

33 (R, G, B) = (255, 255, 255), (255 × (9/10), 255, 255), (255 × (8/10), 255, 255),... , (0, 255, 255) are the same as those shown in FIG. 21 before the regular interval processing, and are arranged at regular intervals in the dummy RGB color space. Also, here, L ^* a ^* b ^* also differs from the case of FIG. 21 in that (L ^* , a ^* , b ^* ) = (L ^* _0,0,0,0 a ^* _{0,0,0, ^{0 b * 0,0,0,0), (L}} * itp1 a * itp1 b * itp1), (L * itp2 a * itp2 b * itp2), ..., (L * 100,0,0,0 a * _100,0,0,0 b ^* _100,0,0,0 ) are arranged at equal intervals in the L ^* a ^* b ^* color space. CMYK values are not defined here. The CMYK values are associated after the K plate constraint conditions for the entire color reproduction region are determined as will be described later.

FIG. 33 illustrates the edge line between W and C, but the L ^* a ^* b ^* values are re-associated with the dummy RGB values on the edge line for all 12 edge lines.

  When such re-association is performed, a gamut mapping algorithm, which will be described later, can be adopted to perform gamut mapping without gradation collapse.

  The above is the processing in the ridge line profile creation process (step (a2)) in FIG.

  Next, processing in the gray axis profile creation process (step (a3)) in FIG. 5 will be described.

Here, a plurality of points are defined at equal intervals on the gray axis connecting the two vertices of W and K in the color reproduction region of the proofer 14 in the dummy RGB color space, and the plurality of points are defined on the L ^* a ^* b ^* color space. A plurality of points mapped on the L ^* a ^* b ^* color space when connecting to, connect the two vertices W and K defined in the color reproduction region defining process (step (a1)) in FIG. Coordinate points in the dummy RGB color space and coordinates in the L ^* a ^* b ^* color space regarding the gray axis of the color reproduction region of the proofer 14 so as to be arranged on the gray axis at equal intervals. A gray axis profile in which points are associated is created.

  FIG. 34 is a diagram showing a table representing the gray axis profile.

Here, (R, G, B) = (255, 255, 255), which is the vertex of W, is associated with (C, M, Y, K) = (0, 0, 0, 0). W point (L ^* , a ^* , b ^* ) on L ^* a ^* b ^* = (L ^* _0,0,0,0 a ^* _0,0,0,0 b ^* _0,0,0,0 ) And the vertex (R, G, B) = (0, 0, 0) of K is the vertex (C, M, Y, K) of K defined as described above = (100, 100). , 100, K _max) L ^* associated with the a ^* b ^* K point above ^{(L *, a *, b} *) = (L * 100,100,100, km a * 100,100,100, km b * 100,100,100, km) in A plurality of points (R, G, B) = (255, 255, 255), (255 × (9 /) which are associated with each other and are equally spaced on the gray axis connecting W and K in the dummy RGB color space. 10), 255 × (9/10)), 255 × (9/10),... 0,0,0) is, L ^* a ^* b ^* equidistant points on the gray axis connecting the W and K in a color space ^{(L *, a *, b} *) = (L * 0,0,0 _{^{, 0 a * 0,0,0,0 b * 0,0,0,0}} ), (L * itp9 / 10 a * itp9 / 10 b * itp9 / 10), (L * itp8 / 10 a * itp8 / _{^{10 b * itp8 / 10),}} ..., it is associated with the _{^{(L * 100,100,100, km a *}} 100,100,100, km b * 100,100,100, km).

Here, the CMYK values need not be calculated and are left blank. L ^* _{itp9 / 10} etc. represents the following.

L ^* _{itpi / 10
^{= L * 0,0,0,0 × i / 10}} + L * 100,100,100, km × (10-i) / 10
a ^* _{itpi / 10
^{= A * 0,0,0,0 × i / 10}} + a * 100,100,100, km × (10-i) / 10
b ^* _{itpi / 10
^{= B * 0,0,0,0 × i / 10}} + b * 100,100,100, km × (10-i) / 10
The reason why the equidistant points on the gray axis of the dummy RGB color space are equally spaced on the gray axis of the L ^* a ^* b ^* color space is the same as the re-association on the ridge line described above. This is to realize gamut mapping without collapse.

  In FIG. 29 and FIG. 30, equidistant points are shown on the gray axis.

  In the profile calculation process (step (a4)) in FIG. 5, the ridge line profile and the gray axis profile obtained in the ridge line profile creation process (step (a2)) and the gray axis profile creation process (step (a3)) are bounded. By the interpolation operation as a condition, a profile other than the edge line of the color reproduction region of the proofer 14 and an internal profile other than the gray axis are calculated.

Here, for each of L ^* a ^* b ^* , the following quadratic formula L ^* = a ₀ R ² + a ₁ G ² + a ₂ B ² + a ₃ RG + a ₄ GB + a ₅ BR + a ₆ R + a ₇ G + a ₈ B + a ₉
a ^* = b ₀ R ² + b ₁ G ² + BB ² + b ₃ RG + b ₄ GB + b ₅ BR + b ₆ R + b ₇ G + b ₈ B + b ₉
b ^* = c ₀ R ² + c ₁ G ² + c ₂ B ² + c ₃ RG + c ₄ GB + c ₅ BR + c ₆ R + c ₇ G + c ₈ B + c ₉
And the points where the dummy RGB values and the L ^* a ^* b ^* values of the edge profile and gray axis profile created as described above are associated with each other as sample points, a _{0 to} a ₉ and b _{0 to} b ₉ , C _{0 to} c ₉ are obtained, and the obtained coefficients are substituted into the above quadratic expression, and the dummyRGB value, the L ^* a ^* b ^* value and the entire color reproduction region of the proofer 14 are calculated. Is associated.

  FIG. 35 is a conceptual diagram showing the color reproduction characteristics (proofer profile) created by associating the entire color reproduction region of such a proofer 14 with each other.

In the profile creation process (see FIG. 5) of step (A) of the color conversion definition creation method of FIG. 4, the proofer profile of the virtual proofer 14 shown in FIG. 1 is thus obtained. This proofer profile is a profile obtained by tracing the color reproduction area of the print, excluding the area exceeding K _max that was discarded as unnecessary.

  Next, the first color conversion definition creating process (step (B)) of the color conversion definition creating method shown in FIG. 4 will be described. Here, the method disclosed in Patent Document 2 described above will be described.

  FIG. 36 is a schematic diagram of color reproduction regions of the printer 11 and the proofer 14 shown in FIG.

FIG. 36A shows an input RGB color space depending on the printer 11, but FIG. 36A shows an RG plane for the sake of simplicity. 36B and 36C are the same, and FIG. 36B shows the L ^* -a ^* plane of the L ^* a ^* b ^* space, which is one of the common color spaces. FIG. 36C shows the RG plane of the dummy RGB color space depending on the proofer 14.

  The printer 11 prints out the print image 11a based on the image data representing the numerical values of 0 to 255 for each of R, G, and B. In this case, the color reproduction area of the printer 11 is shown in FIG. A rectangular area 101 shown in FIG.

Here, referring to the color reproduction characteristics (printer profile 51) of the printer 11 shown in FIG. 13, the color reproduction area 101 of the printer 11 shown in FIG. 36A is mapped to the L ^* a ^* b ^* space. The color reproduction region of the printer 11 is represented as a region 102, and the color reproduction region 102 is further represented by the color reproduction characteristic (proofer profile 53 (see FIG. 16) of the proofer 14 created as described above. )) And mapping to the dummy RGB color space depending on the proofer 14, the color reproduction area of the printer 11 is represented as shown in an area 103 in FIG. 36C.

On the other hand, the color reproduction region (proofer profile) of the proofer 14 shown in FIG. 1 is a cubic region indicated by a numerical range of 0 to 255 for R, G, and B on the dummy RGB color space of FIG. (A rectangular region 303 on the RG plane in FIG. 36C). That is, image data representing coordinate points within a numerical range of 0 to 255 for each of R, G, and B in the input RGB color space depending on the printer 11 is transferred to the dummy RGB color space via the L ^* a ^* b ^* space. When converted to image data, a value exceeding the color that can be expressed by the proofer 14 (range of 0 to 255 for both RGB on the image data), for example, (R, G) = as illustrated in FIG. (110, 290) or (R, G) = (− 100, 260) may be converted into a value. In this case, since these image data, that is, image data outside the color reproduction area of the proofer 14 cannot be output by the proofer 14, the image data becomes image data located at the boundary of the color reproduction area of the proofer 14. In the past, it has been proposed to clip as described above. Specifically, (R, G) = (110,290) is changed to (R, G) = (110,255), and (R, G) = (− 100,260) is changed to (R, G). ) = (0,255).

  In the case of mapping in a color space that depends on the side to be converted (here, the proofer 14), the degree of freedom of mapping is small, and data out of the color reproduction area of the proofer 14 as described above is simply clipped. Mapping is performed only by moving to the boundary of the color reproduction area, and in mapping from the color reproduction area of one device (for example, the printer 11) to the color expression area of another device (for example, the proofer 14), In some cases, the accuracy of mapping in the vicinity of the boundary of these color expression regions is greatly reduced.

On the other hand, when the color reproduction area 303 of the proofer 14 indicated by a rectangular area of 0 to 255 in FIG. 36C is mapped to the L ^* a ^* b ^* space using the color reproduction characteristics (proofer profile) of the proofer 14. This is represented as a region 302 shown in FIG. In the common color space represented by the L ^* a ^* b ^* space, the data in the color reproduction area 102 of the printer 11 (first device) is converted into the data in the color reproduction area 302 of the proofer 14 (second device). Several methods have been proposed in the past for converting to.

In color conversion (mapping) in the L ^* a ^* b ^* space, when an attempt is made to use the color reproduction region that can be expressed by the proofer 14 as widely as possible, in general, a broken line arrow in FIG. As shown in FIG. 36, “compression” for mapping data out of the common area 402 of the color reproduction area 101 of the printer 11 and the color reproduction area 302 of the proofer 14 to the inside of the common area 402, and FIG. As indicated by the solid line arrow, the data in the common area 402 is both expanded and extended to the outside of the common area 402 while maintaining the condition that it is inside the color reproduction area 302 of the proofer 14. It is.

Conventionally proposed mapping in a common color space represented by the L ^* a ^* b ^* space has a risk that the degree of freedom of mapping is too large and the tone becomes discontinuous or the image looks unnatural. The nature is great.

When the color reproduction area 302 of the proofer 14 mapped in the L ^* a ^* b ^* space of FIG. 36B is further mapped to the input RGB color space of FIG. 36A, a rectangular color reproduction area of the printer 11 is obtained. It is expressed as a “squishy” shaped region 301 with a portion protruding from the region 101.

Next, the common color space will be described. As for the common color space, the L ^* a ^* b ^* color space has been described as one example, but the L ^* a ^* b ^* color space is not necessarily required and depends on a specific input device or a specific output device. Any color space that is defined so as not to occur may be used. For example, in addition to the L ^* a ^* b ^* color space, an XYZ color space may be used, or each coordinate point on the color space is clearly defined so as to correspond to the color space on a one-to-one basis. It may be a coordinate system. An example of such a coordinate system is a standard RGB signal defined as follows.

Here, for example, if R _SRGB is expressed in 8 bits, it is expressed in R _{8 bits} .
R _8bit = 255 × 12.92R _SRGB (0 <R _SRGB <0.00304)
R _8bit = 255 × 1.055R _SRGB ^{(1.0 / 2.4)} −0.055
(0.00304 ≦ R _SRGB ≦ 1)
It becomes. Similarly, G _8bit and B _8bit expressing G _SRGB and B _SRGB with 8 bits can be converted from G _SRGB and B _SRGB , respectively.

  Alternatively, a color space defined by the CMY density of the reversal film may be adopted as the common color space. When the common color space is defined, the color reproduction region in the common color space is clearly defined.

  FIG. 37 is a flowchart showing a first color conversion definition creating process in the color conversion definition creating method by the color conversion definition creating program executed in the computer system shown in FIGS. FIG. 36 generally corresponds to the first color conversion definition creation process in step (B) of FIG.

  Here, the first color conversion definition referred to in the present invention is obtained through the first coordinate conversion process (step b1), the second coordinate conversion process (step b2), and the third coordinate conversion process (step b3). Created. In the second coordinate conversion process (step b2), the first process (step b22) is basically executed. In the present embodiment, the first process is performed so that a more accurate color conversion definition is created. A second process (step b21) is placed before the process.

  FIG. 38 is a block diagram showing the configuration of the first color conversion definition creating unit 32 (see FIG. 7) in the color conversion definition creating program executed in the computer system shown in FIGS. is there.

  The first color conversion definition creating unit 32 includes a first coordinate conversion unit 321, a second coordinate conversion unit 322, and a third coordinate conversion unit 323. The second coordinate conversion unit 322 further includes: It consists of a first part 322a and a second part 322b executed before the first part 322a.

  FIG. 39 shows the first color conversion in the color conversion definition creation device 40 constructed in the computer 20 by executing the color conversion definition creation program in the computer 20 shown in FIGS. It is a functional block diagram of the definition creation part 42 (refer FIG. 10).

  The first color conversion definition creation unit 42 includes a first coordinate conversion unit 421, a second coordinate conversion unit 422, and a third coordinate conversion unit 423. The second coordinate conversion unit 422 further includes It consists of a first part 422a and a second part 422b arranged in front of the first part 422a.

  Here, steps b1, B (B1, B2), b3 of the first color conversion definition creating process in the color conversion definition creating method shown in FIG. 37 are the first color conversion definition creating unit shown in FIG. 32 respectively correspond to the respective units 321, 322 (322 a, 322 b), 323, and each of the units 421, 422 (422 a, 422 b), 423 configure the first color conversion definition creating unit 42 shown in FIG. 39. In the following, the steps b1, B (B1, B2), and b3 of the first color conversion definition creation process in FIG. 37 will be described and explained, so that the first color conversion definition creation in FIG. 38 is performed. The description of each part 321, 322 (322a, 322b), 323 of the part 32 and each part 421, 422 (422a, 422b), 423 of the first color conversion definition creating part 42 of FIG. And the.

  In the following, each process (steps b1, b2 (b21, b22), b3) constituting the first color conversion definition creating process shown in FIG. 37 will be described in order.

First, in step b1 of FIG. 37, the color reproduction characteristics (printer profile) of the printer 11 are referred to, and each coordinate point in the input RGB color space depending on the printer 11 (here, the coordinate point on each grid set to be discrete). ) Are mapped to a device independent common color space (for example, L ^* a ^* b ^* space).

FIG. 40 is an explanatory diagram of the second process in the second coordinate conversion process executed in step b1 of FIG. 37, and the color reproduction region of the printer 11 and the color reproduction of the proofer 14 in the L ^* a ^* b ^* space. Indicates the area.

Here, adaptation conversion is performed by applying concretion conversion (Von Kries conversion). That is, here, the coordinate point W ₁ corresponding to white (the paper color of the print image 11a) represented by the print image 11a (see FIG. 1) printed out by the printer 11 and the print image 11a are represented. The coordinate point B ₁ corresponding to the black that can be printed (the state in which the printer 11 has printed the maximum amount of each color ink of R, G, and B) is the white color of the proof image that is virtually output by the proofer 14 ( as proof image coordinate point W ₃ corresponding to the color) of the sheet of black that can be output by the proofer 14 (the proofer 14 R, G, ink of each color of B color) was printed using the maximum amount of Coordinate conversion is performed so as to coincide with the corresponding coordinate point B ₃ .

FIG. 40 shows this coordinate conversion process. First, the color reproduction region 102a of the printer 11 and the color reproduction region 302a of the proofer 14 shown in FIG. 40A are shown in FIG. 40B. Then, the black spots B ₁ and B ₃ are translated so as to coincide with the origin 0 (theoretical black spot). Thereby, first, the black spot of the color reproduction area 102b of the printer 11 and the black spot of the color expression area 302b of the proofer 14 coincide.

Next, the white point W ₁ of the color reproduction area 102b of the printer 11 after the parallel movement is made to coincide with the white point W ₃ of the color reproduction area 302b of the proofer 14 after the parallel movement, that is, FIG. as the straight line L ₁ of B) coincides with the straight line L _3, coordinate conversion involving rotation and expansion for the entire color reproduction area 102b of the printer 11 is performed.

FIG. 40C shows a state after the coordinate conversion accompanied by this rotation and expansion / contraction, and the color reproduction region of the printer 11 is changed from the color reproduction region 102b shown in FIG. 40B to FIG. The color reproduction area 102c shown in FIG. At this time, the white point W ₁ of the color reproduction region of the printer 11 matches the white point W ₃ of the color reproduction region of the proofer 14.

Thereafter, as shown in FIG. 40D, the color reproduction region 102c of the printer 11 in which the white point and the black point coincide with each other as shown in FIG. 40C, the original color reproduction region of the proofer 14, that is, As shown in FIG. 40A, the color reproduction region 302a of the proofer 14 moves in parallel to a position that coincides with the white point W ₃ and the black point B ₃ .

By doing so, it is possible to obtain the color reproduction region 102d of the printer 11 in which the white point W ₁ and the black point B ₁ coincide with the white point W ₃ and the black point B ₃ of the proofer 14, respectively.

The above operation can be expressed as follows. FIG. 40 shows the color reproduction area in the L ^* a ^* b ^* space. However, the above-described adaptation conversion using the concrete conversion and the concrete conversion is often executed in the XYZ space. Here, the XYZ space is used. An explanation will be given assuming this. This XYZ space is one of common color spaces in which each coordinate point has a one-to-one correspondence with each coordinate point in the L ^* a ^* b ^* space.

The XYZ coordinates of the white point W ₁ and black point B ₁ of the color reproduction area 102a of the printer 11 shown in FIG. 40A are (LXW ₁ , LYW ₁ , LZW ₁ ) and (LXB ₁ , LYB ₁ , LZB ₁ ), respectively. XYZ coordinates of the white point W ₃ and black point B ₃ of the color reproduction region 302a of the proofer 14 shown in FIG. 40A are (LXW ₃ , LYW ₃ , LZW ₃ ), (LXB ₃ , LYB ₃ , LZB ₃ ), respectively. XYZ coordinates (LXW ₁ ′, LYW ₁ ′, LZW ₁ ′), (LXW ₃ ′, LYW ₃ ′, LZW ₃ ′) corresponding to the white points W ₁ , W ₃ shown in FIG. ) For each formula LXW ₁ ′ = LXW ₁ −LXB ₁
LYW ₁ '= LYW ₁ -LYB ₁
LZW ₁ '= LZW ₁ -LZB ₁ (1)
LXW ₃ '= LXW ₃ -LXB ₃
LYW ₃ '= LYW ₃ -LYB ₃
LZW ₃ '= LZW ₃ -LZB ₃ (2)
The concrete for rotating and expanding and contracting so that the white point W ₁ (LXW ₁ ′, LYW ₁ ′, LZW ₁ ′) coincides with the white point W ₃ (LXW ₃ ′, LYW ₃ ′, LZW ₃ ′). Create a Von Kries matrix.

Here, this concrete matrix is
VK = [MTX _VK ] (3)
Is written. This concrete matrix is a matrix of 3 rows × 3 columns.

Next, in step b1 in FIG. 37, the coordinate points in the input RGB space depending on the printer 11 are mapped to the L ^* a ^* b ^* space and further converted into the XYZ space (or the input RGB depending on the printer 11). Representing a large number of coordinate points (mapped directly from the color space to the XYZ space) as (X, Y, Z)
This (X, Y, Z) is
X1 = X-LXB ₁
Y1 = Y-LYB ₁
Z1 = Z-LZB ₁ (4)
To correct the black spot (see FIG. 40B).

The concrete conversion is performed by the following (see FIG. 40C), and then X ′ = X2-LXB ₃
Y '= Y2-LYB ₃
Z ′ = Z2−LZB ₃ (6)
Thus, correction (see FIG. 40D) for making the black point coincide with the black point of the proofer 14 is performed.

By performing the above calculation for all coordinate points, the color reproduction region 102a of the printer 11 shown in FIG. 40A when expressed in the L ^* a ^* b ^* space has the white point and the black point the color of the proofer 14. It is converted into a color reproduction region 102d shown in FIG. 40 (D) that matches the white point and black point of the reproduction region 302a.

When the above-described adaptation conversion is performed in the XYZ space, the coordinates (X, Y, Z) of the black points (black points B ₁ , B _{3 in} FIG. 40A) before the adaptive conversion are almost close to (0, 0, 0). Therefore, the correction of the black point only changes the numerical value slightly, and even if the coordinates of the white point are moved according to the equations (1) and (2), the amount of movement is small, and a wide area in the XYZ space. However, this adaptation change does not necessarily have to be performed in the XYZ space, but may be performed in the L ^* a ^* b ^* space, or other It may be performed in a common color space.

  In this example, the adaptation conversion for matching both the white point and the black point has been described. However, although the accuracy of the color conversion is slightly reduced, for simplicity, only the white point is matched without considering the black point. Adaptation conversion may be performed.

The adaptation conversion for matching only the white point will be described with reference to FIG. 40. The straight line L ₁ ′ shown in FIG. 40A matches the straight line L ₃ ′, and the white point W ₁ matches the white point W ₃ . In terms of mathematical expression, the white point W ₁ (LXW ₁ , LYW ₁ , LZW ₁ ) is white without subtracting the black point coordinates as in Equations (1) and (2). A concrete matrix for rotating and expanding and contracting so as to coincide with the point W ₃ (LXW ₃ , LYW ₃ , LZW ₃ ) is obtained. This means that (X, Y, Z) is converted as it is using a matrix.

  Further, this adaptation conversion is performed when, for example, “white” on the CRT display display screen is a bluish white and the image displayed on the CRT display display screen needs to be printed out. This is necessary in the case of color conversion between devices having white that is considerably distant from each other. For example, a print image 11a printed on a white paper by the printer 11 and a similar white paper by a virtual proofer 14 are printed. When both whites are almost identical, as in the case of comparing with the proof image when it is assumed to be output, this adaptation conversion, that is, the second process of the second coordinate conversion process of FIG. (Step B1) may be omitted.

  Next, some examples of the first process (step B2) in the second coordinate conversion process of the flowchart shown in FIG. 37 will be described.

FIG. 41 is an explanatory diagram of a first example of coordinate transformation in the first process, and FIG. 42 is a flowchart of the first example. In FIG. 41, the L ^* -a ^* plane in the L ^* a ^* b ^* space is clearly shown, but this is for the convenience of illustration, and in fact, L ^* a ^* b ^* A three-dimensional coordinate transformation is performed in the space. The same applies not only to FIG. 41 but also to various examples described later.

Here, first, a coordinate conversion reference coordinate point c that serves as a reference for coordinate conversion is set. The coordinate conversion reference coordinate point c is set arbitrarily to some extent empirically or in accordance with a predetermined setting standard, but the color reproduction region 102 of the printer 11 and the color reproduction of the proofer 14 mapped in the L ^* a ^* b ^* space. It is set in a common area with the area 302. Further, the coordinate conversion reference coordinate point c is within the common area, and is set on the L ^* axis (gray axis) in the present embodiment. By doing so, as will be understood from the following description, this coordinate conversion reference coordinate point c is not mapped to other coordinate points, and therefore it is easy to maintain the gray balance. Here, for example, a point of (L ^* , a ^* , b ^* ) = (50, 0, 0) is set as the coordinate conversion reference coordinate point c.

When the second coordinate transformation process (step b2) in the flowchart of FIG. 37 includes the adaptation transformation (step b1) as described with reference to FIG. 40, it is mapped to the L ^* a ^* b ^* space. The color reproduction area 102 of the printer 11 indicates the color reproduction area after the adaptation conversion.

Here, a coordinate point in the color reproduction region 102 of the printer 11 in the L ^* a ^* b ^* space to be mapped is set as the first coordinate point t.

  Here, a straight line connecting the coordinate conversion reference coordinate point c and the first coordinate point t is considered, and an intersection between the straight line and the boundary of the color reproduction region 102 of the printer 11 is obtained (step S11 in FIG. 42). Here, this intersection is called a first reference coordinate point a.

In the flowchart shown in FIG. 42, the first reference coordinate point a thus obtained is out of the color reproduction region 302 of the proofer 14 mapped in the L ^* a ^* b ^* space as shown in FIG. When this condition is satisfied, the processing is further advanced as follows.

The first reference coordinate point a obtained as described above is mapped from the L ^* a ^* b ^* space to the dummy RGB color space depending on the proofer 14 (step S12 in FIG. 42). Let P ₁ be the _first reference coordinate point mapped to this dummy RGB color space.

Then, in dummyRGB color space, by clipping the first coordinate value of the reference coordinate point P ₁ thereof, the reference coordinate point P ₁ of the first, the dummyRGB color space, the color reproduction area of the proofer 14 Mapping on the boundary (step S13). The point P ₂ obtained on the boundary of the color reproduction region of the proofer 14 by this mapping is now mapped from the dummy RGB color space to the L ^* a ^* b ^* space (step S14). A coordinate point mapped in the L ^* a ^* b ^* space is set as a second reference coordinate point b (see FIG. 41).

  Next, a basic that represents the difference between the first reference coordinate point a and the second reference coordinate point b shown in FIG. 41, with the first reference coordinate point a as the start point and the second reference coordinate point as the end point. The difference vector v is obtained (step S15), and the first coordinate point t to be mapped is set in the same direction as the direction of the basic difference vector v with the coordinate conversion reference coordinate point c and the second reference coordinate point. The point is moved to a straight line connecting b, and the point is set as a second coordinate point s to which the first coordinate point t is mapped (step S16).

Of the coordinate points included in the color reproduction area 102 of the printer 11 mapped in the L ^* a ^* b ^* space, the first reference coordinate point a obtained in step b1 is the printer. This is performed for all coordinate points outside the 11 color reproduction regions 102 (step 17).

As described above, the coordinate transformation described with reference to FIGS. 41 and 42 determines the direction of the coordinate transformation, that is, when determining the basic difference vector v, the dummy RGB color space is used to determine the direction of the coordinate transformation. This is done by defining a second reference coordinate point b on the boundary of the color reproduction region of the proofer 14 corresponding to the first reference coordinate point a on the boundary of the color reproduction region, and the actual mapping is L ^* a ^* b ^* Performed in space.

That is, since the direction of coordinate conversion (mapping) is determined in a color space that matches the human color sense of the dummyRGB color space (device-dependent color space), the tone discontinuity or unnatural image results. The fear is suppressed to a very low level, and the actual coordinate conversion is performed in the L ^* a ^* b ^* space (common color space), so that highly accurate coordinate conversion (mapping) is performed in terms of color.

  Note that FIG. 41 is drawn so that coordinate transformation (mapping) is performed on a two-dimensional plane for convenience of illustration, but as described above, three-dimensional mapping is actually performed. .

  FIG. 43 is a diagram illustrating a modification of the coordinate conversion described with reference to FIGS. 41 and 42.

  Here, a region D surrounding the coordinate conversion reference coordinate point c is set, and an intersection d between the straight line connecting the coordinate conversion reference coordinate point c and the first reference coordinate point a and the boundary of the region D is obtained. In mapping the coordinate point t, the coordinate point t is mapped to a coordinate point s on a straight line connecting the intersection d and the second reference coordinate point b.

By doing so, it is possible to set an area D where the coordinates do not move. As described above, it has been described that it is preferable not to move the coordinates for the L ^* axis (gray axis) in order to maintain the gray balance. However, the coordinates are moved by setting the region D as shown in FIG. The area not to be set can be arbitrarily set.

  FIG. 44 is an explanatory diagram of a second example of coordinate transformation in the first step of the flowchart shown in FIG. 37, and FIG. 45 is a flowchart of the second example.

Here, as in the first example described with reference to FIGS. 41 and 42, a coordinate conversion reference coordinate point c that is a reference for coordinate conversion is set on the L ^* axis (gray axis).

Consider a straight line connecting the coordinate conversion reference coordinate point c and the first coordinate point t to be subjected to coordinate conversion, and the straight line and the color reproduction region 102 of the printer 11 mapped in the L ^* a ^* b ^* space. An intersection with the boundary is obtained (step S21). This intersection is called a first reference coordinate point a. Here, the color reproduction region 102 of the printer 11 mapped in the L ^* a ^* b ^* space is subjected to the adaptive conversion in the second process (step b2) of the flowchart of FIG. As described above, it indicates the reproduction region.

The flowchart shown in FIG. 44 is different from the flowchart shown in FIG. 42, and the proofer 14 in which the first reference coordinate point a thus obtained is mapped to the L ^* a ^* b ^* space as shown in FIG. Is a flowchart in the case of existing within the color reproduction region 302. When this condition is satisfied, the processing is further advanced as follows.

  The second reference coordinate point b on the boundary of the color reproduction area of the proofer 14 corresponding to the first reference coordinate point a on the boundary of the color reproduction area of the printer 11 is obtained (step). S22). In obtaining the second reference coordinate point b, here, as shown in FIG. 44, the first reference coordinate point a exists inside the color reproduction region 302 of the proofer 14, and therefore FIG. 41 and FIG. The method described with reference to cannot be used. That is, even when the first reference coordinate point a is outside the color reproduction area 302 of the proofer 14, the first reference coordinate point a is mapped to the dummyRGB color space. The first reference coordinate point is located inside the color expression area of the proofer 14 in the dummy RGB color space, and the above-described clip method cannot be used. Therefore, here, the second reference coordinate point b is obtained as follows.

First, all points on the boundary of the color reproduction area (gamut) of the proofer 14 in the dummy RGB color space (represented by the point P ₁ ) are mapped from the dummy RGB color space to the L ^* a ^* b ^* space (step S 221). Further, all the points P ₂ mapped to the L ^* a ^* b ^* space are mapped to the input RGB color space (step S222). Next, of the points P ₃ mapped to the input RGB color space, the points out of the color reproduction area of the printer 11 on the input RGB color space are negative for each of R, G, B, for example, as described above. The value of 0 is clipped to 0, and the value exceeding 255 is clipped to 255, thereby mapping on the boundary of the color reproduction area of the printer 11 (step S223).

All the points P ₄ mapped in the input RGB color space and clipped as described above are mapped from the input RGB color space to the L ^* a ^* b ^* space (step S224). Of the points P ₅ mapped in the L ^* a ^* b ^* space in this way, the closest point P ₅ ′ that matches or does not match the first reference coordinate point a is found, and the dummyRGB color. space, among all the points P ₁ on the boundary of the color reproduction area of the proofer 14, find the point P ₅ 'obtained point was based P ₁ a', the second reference coordinates the points P ₁ ' Point b is set (step S225).

  By following such a procedure, the second reference coordinate point b corresponding to the reference coordinate point a shown in FIG. 44 can be obtained.

In the flowchart shown in FIG. 45, all the points P ₁ on the boundary of the color reproduction area of the proofer 14 in the dummy RGB color space are uniformly mapped to the input RGB color space. However, L ^* a ^* shown in FIG. b ^* of the coordinate points on the boundary of the color reproduction area 302 of the proofer 14 mapped to the space, L ^* a ^* b ^* coordinate points of the portion protruding from the color reproduction area 102 of the printer 11 mapped onto only, What is necessary is just to map to the input RGB color space, or when the coordinate position of the second reference coordinate point b can be further narrowed down by guessing or the like among the protruding portions, the coordinates in the narrowed region Only the points may be mapped to the input RGB color space and clipped.

  When the second reference coordinate point b is detected in step S22 shown in FIG. 45, the second reference coordinate point a is changed from the first reference coordinate point a as shown in FIG. 44, as in the case of the flowchart of FIG. A basic difference vector v toward the point b is obtained (step S23), and further, a second coordinate point corresponding to the first coordinate point is obtained in the same manner as in the first example of FIGS. Step S24).

Such coordinate conversion is performed by the first reference coordinate point a obtained in step c1 among the coordinate points in the color reproduction region 102 of the printer 11 mapped in the L ^* a ^* b ^* space. The process is performed for all coordinate points existing in the expression area 302 (step S25).

  FIG. 46 is a diagram illustrating a modification of the second example of coordinate transformation described with reference to FIGS. 44 and 45.

  Here, similarly to FIG. 43, a region D surrounding the coordinate conversion reference coordinate point c is set, and an intersection of a straight line connecting the coordinate conversion reference coordinate point c and the first reference coordinate point a and the boundary of the region D is set. d is obtained, and the first coordinate point t is mapped to a coordinate point s on a straight line connecting the intersection d and the second reference coordinate point b. By doing so, it is possible to set the region D where the coordinates are not moved.

  FIG. 47 is a diagram for explaining the effect of mapping performed by combining the “compression” described with reference to FIGS. 41 and 42 and the “decompression” described with reference to FIGS. 44 and 45.

L ^* a ^* b ^* coordinate point it is the broad line LN1 of the color reproduction area 102 L ^* a ^* b ^* color representation area 302 of the proofer 14 of the space than the printer 11 in space, the color of the proofer 14 Each of the coordinate points on the line LN2 that is expanded so as to use the reproduction area 302 to the maximum and the color reproduction area 102 of the printer 11 is wider is compressed to a level that uses the color reproduction area 302 of the proofer 14 to the maximum. Since the directions of expansion and compression are obtained by using the RGB space depending on the device, even if mapping itself is performed in the L ^* a ^* b ^* space, the discontinuity of the tone or unnaturalness is unsatisfactory. Image generation is prevented, and mapping itself is performed in the L ^* a ^* b ^* space, so that high-precision mapping is performed. In addition, each coordinate point on the line LN3 in which the color reproduction area 102 of the printer 11 and the color expression area 302 of the proofer 14 coincide with each other does not move and the color is maintained as it is.

Note that the mapping performed here is depicted in FIG. 47 as if it was performed on the L ^* -a ^* plane for convenience of illustration, but it is performed three-dimensionally as described above. is there.

FIG. 48 is an explanatory diagram of a third example of coordinate transformation in the first step of the flowchart shown in FIG. 37, and FIG. 49 is a flowchart of the third example. In the third example described here, as in the case of the second example described with reference to FIGS. 44 and 45, the first reference coordinate point a1 obtained in step S31 is the L ^* a ^* b ^* space. This is an example of the case where the image is present inside the color reproduction region 302 of the proofer 14 mapped to.

Here, as in the first and second examples described above, a coordinate conversion reference coordinate point c serving as a reference for coordinate conversion is set on the L ^* axis (gray axis), and the coordinate conversion reference coordinate point c and the coordinate are set. Considering a straight line connecting the first coordinate point t to be converted, the intersection of the straight line and the boundary of the color reproduction area 102 of the printer 11 mapped in the L ^* a ^* b ^* space is obtained, and the intersection is determined. A first reference coordinate point a1 is obtained. Further, an intersection point between the straight line and the boundary of the color expression area 302 of the proofer 14 mapped in the L ^* a ^* b ^* space is obtained, and the intersection point is determined as a third reference coordinate point a2. (Step S31). The color reproduction area 102 of the printer 11 mapped in the L ^* a ^* b ^* space is the color reproduction area after the adaptive conversion when the adaptive conversion is performed in the second step (step b21) of the flowchart of FIG. It is the same as in the first and second examples so far.

Next, the third reference coordinate point a2 obtained as described above is mapped from the L ^* a ^* b ^* space to the input RGB color space depending on the printer 11 (step S22), and mapped to the input RGB color space. The point P ₁ is clipped in the input RGB color space so as to be mapped on the boundary of the color reproduction area of the printer 11 (step S33), and the point P ₂ obtained by the mapping is mapped in the L ^* a ^* b ^* space. Mapping is performed (step S34). A point on the boundary of the color reproduction area 102 of the printer 11 in the L ^* a ^* b ^* space obtained in this way is referred to as a fourth reference coordinate point B.

Next, a difference vector v1 from the third reference coordinate point a2 toward the fourth reference coordinate point B is obtained (step S35), and a straight line passing through the first reference coordinate point a1 and parallel to the difference vector v1 is considered. The intersection of the straight line and the boundary of the color reproduction area 302 of the proofer 14 in the L ^* a ^* b ^* space is defined as a second reference coordinate point b1, and the first reference coordinate point a1 to the second reference coordinate point. A basic difference vector v toward b1 is obtained (step S36). Thereafter, similarly to the first and second examples described so far, the first coordinate point t moves the first coordinate point t parallel to the basic difference vector v, and the coordinate conversion reference coordinate point c And the second reference coordinate point b1 are mapped to the coordinate point (second coordinate point s) that collides with a straight line (step S37).

Such coordinate transformation, L ^* a ^* b ^* of the coordinate points in the color reproduction area of the printer 11 in space, in step d1, L ^* a ^* b ^* color representation area 302 of the proofer 14 in space Is performed for all the coordinate points for which the first reference coordinate point a1 located inside is obtained (step S38).

The third example shown in FIGS. 48 and 49 shows a case where the color reproduction area 102 of the printer 11 and the color reproduction area 302 of the proofer 14 in the L ^* a ^* b ^* space are greatly shifted, that is, the difference vector v1. When the basic difference vector v is far away, there is an error, but when the distance between the two vectors v1 and v is close and the error between the two vectors v1 and v can be ignored, this third example As compared with the second example described with reference to FIGS. 44 and 45, high-speed calculation is possible.

  FIG. 50 is a diagram illustrating a modification of the third example of coordinate transformation described with reference to FIGS. 48 and 49.

  43 and 46, a region D surrounding the coordinate conversion reference coordinate point c is set, and a straight line connecting the coordinate conversion reference coordinate point c and the first reference coordinate point a1 and the region D An intersection d with the boundary is obtained, and the first coordinate point t is mapped on a straight line connecting the intersection d and the second reference coordinate point b1.

  In this way, it is possible to set the region D where no coordinate movement is performed.

  51 is an explanatory diagram of a fourth example of coordinate transformation in the first step of the flowchart shown in FIG. 37, and FIG. 52 is a flowchart of the fourth example.

In the fourth example, the first reference coordinate point a obtained in step e1 exists inside the color reproduction area 302 of the proofer 14 mapped in the L ^* a ^* b ^* space, or from the color reproduction area 302. It is a method that can be applied without considering whether it is off.

Here, as in the first to third examples described above, the coordinate conversion reference coordinate point c is set on the L ^* axis (gray axis), and the coordinate conversion reference coordinate point c and the second coordinate conversion target. Considering a straight line connecting one coordinate point t, an intersection between the straight line and the boundary of the color reproduction area 102 of the printer 11 in the L ^* a ^* b ^* space is obtained, and the intersection is determined as a first reference coordinate point a. (Step S41).

  Next, the first reference coordinate point a is mapped to the input RGB color space which is a color space depending on the printer 11 (step S42).

Next, a coordinate value corresponding to the coordinate value of the point P ₁ on the input RGB color space mapped to the input RGB color space in this way, typically the same coordinate value as the coordinate value of the point P ₁ is obtained. A coordinate point P ₂ on the dummy RGB color space, which is a color space depending on the proofer 14, is obtained (step S 43). As a specific example, when the coordinate value of the point P _{1 obtained} by mapping the first reference coordinate point a shown in FIG. 51 into the input RGB color space is (R, G, B) = (0, 255, 0). , the same coordinate values (R, G, B) = (0,255,0) and the point P ₂ to the point on dummyRGB color space with.

Then the point P ₂ of dummyRGB color space is mapped from dummyRGB color space to the L ^* a ^* b ^* space, a point which is the mapping between the second reference coordinate point b (step S44).

Since the first reference coordinate point a is a point on the boundary of the color reproduction area 102 of the printer 11 in the L ^* a ^* b ^* space, the first reference coordinate point a is mapped to the input RGB color space. Is a point on the boundary of the color reproduction region of the printer 11 in the input RGB color space (for example, (R, G, B) = (0, 255, 0) described above).

If this is used as a point in the dummy RGB color space as it is, it becomes a point on the boundary of the color reproduction area of the proofer 14 in the dummy RGB color space, and this point is obtained by mapping the point to the L ^* a ^* b ^* space. The second reference coordinate point b is also a point on the boundary of the color reproduction region 302 of the proofer 14 in the L ^* a ^* b ^* space.

  A basic difference vector v from the first reference coordinate point a thus determined to the second reference coordinate point b is obtained (step e5), passes through the first coordinate point t, and is parallel to the basic difference vector v. A second coordinate point s which is an intersection of the drawn straight line and a straight line connecting the coordinate conversion reference coordinate point c and the second reference coordinate point b is obtained (step S46).

The above coordinate conversion is sequentially performed for the entire color reproduction region 102 of the printer 11 in the L ^* a ^* b ^* space.

  FIG. 53 is a diagram showing a modification of the fourth example of coordinate transformation described with reference to FIGS. 51 and 52.

  Here, as in the examples of FIGS. 43, 46, and 50, a region D is set around the coordinate conversion reference coordinate point c, and the region D is not mapped. The method for preventing the area D from being mapped is the same as in the examples of FIGS. 43, 46, and 50, and a description thereof will be omitted.

  Next, returning to FIG. 37, the third coordinate conversion process (step b3) will be described.

In the third coordinate conversion process (step b3), coordinate conversion (mapping) from the color reproduction area 102 of the printer 11 to the color reproduction area 302 of the proofer 14 is performed in the L ^* a ^* b ^* space. Each coordinate point in the color reproduction region 302 of the proofer 14 is mapped to the dummy RGB color space based on the color reproduction characteristic (proofer profile) of the proofer 14.

  In the first color conversion definition creating process (step (B)) of the color conversion definition creating method shown in FIG. 4, the printer 11 in the input RGB color space, which is a color space dependent on the printer 11, as described above. Within the color reproduction area of the proofer 14 in the dummyRGB color space, which is a color space that depends on the virtual proofer 14 having a color reproduction area sufficiently matching the coordinate reproduction point in the color reproduction area. A first color conversion definition for conversion to a coordinate point (within a color reproduction region sufficiently matching the color reproduction region of the printing system 12) is obtained.

  Next, the process of the second color conversion definition creation process (step (C)) in FIG. 4 will be described.

  In the second color conversion definition creating process (step (C)), each process of the profile creating method of FIG. 6, that is, the K value defining process (step (c1)), the K value calculating process (step (c2)). And the K value constraint condition utilization process (step (c3)) are performed, and the proofer profile (see FIG. 16) created in the profile creation process (step (A)) in FIG. 4 is associated with CMYK. As a result, the link profile 54 (see FIG. 17) in which the coordinate points (dummyRGB values) in the dummyRGB color space are associated with the CMYK values is obtained.

  First, in the K value definition process (step (c1)), for the color reproduction region of the proofer 14 obtained in the profile creation process (step (A)) in FIG. (C) The value of K obtained by (see FIG. 15) is adopted, and the WMRY plane surrounded by ridge lines sequentially connecting W-M-R-Y-W and W-Y-G-C-W are sequentially connected. For the WYGC plane surrounded by the ridge lines and the WCBM plane surrounded by the ridge lines sequentially connecting W-C-B-M-W, a value of K ≦ 0 is adopted, and RK ridge lines connecting RK , GK ridge line connecting G-K and BK ridge line connecting BK, by adopting a K value of K ≧ 0, the color reproduction region of the second device on the gray axis, the WMRY surface Above, on WYGC surface, on WCBM surface, on RK ridgeline, on GK ridgeline, and The value of K is defined for each point on BK edge line.

  Specifically, for the gray axis of R = G = B, a K value is assigned to each point on the gray axis using the K plate constraint condition K = K (C).

  FIG. 54 is a diagram showing the functional form of the K value assigned to each point on the WMRY surface, the WYGC surface, and the WCBM surface.

  Each point on three surfaces (WMRY, WYGC, and WCBM surfaces; including the remaining nine ridge lines excluding the RK ridge line, the GK ridge line, and the BK ridge line) in contact with the white point W on the color reproduction region In order to reproduce colors by printing, the value of K is preferably K = 0. In addition, the K-value on the gray axis (K plate constraint condition (see FIG. 15)) because the region close to W of these three surfaces (WMRY surface, WYGC surface, and WCBM surface) has a short distance from the gray axis. Therefore, when a K plate constraint condition is given in which the K value suddenly increases from the W point toward the K point, the WMRY surface, WYGC surface, There is a concern that the value of K in the vicinity of the WCBM surface becomes K> 0.

Therefore, here, for each point on the three surfaces of the WMRY surface, the WYGC surface, and the WCBM surface, as shown in FIG.
Chroma = Max (R, G, B) −Min (R, G, B)
However, Max (R, G, B) is the maximum value of the R, G, B values at that point,
Min (R, G, B) is the minimum value of the R, G, B values at that point.
Represents.
The value of K obtained by using as a variable is assigned.

  In FIG. 54, when Chroma = 0, Kmin and Chroma = 255 (here, the maximum values of R, G, and B are 255) of the CK curve (K = K (C)) shown in FIG. In some cases, a function form with K = 0 is adopted, and a point with low saturation (point close to W) on the WMRY surface, WYGC surface, and WCBM surface is a negative value having a large absolute value as the value of K. A value is assigned and approaches K = 0 as it goes to higher saturation, and K = 0 is assigned to each vertex of R, G, B, C, M, and Y, and R, G, B, C, M, and Y K continuity with an area to which K> 0 is assigned that is closer to K than each vertex is ensured.

  FIG. 55 is a diagram illustrating an example of a functional form of the K value assigned to each point on the RK ridgeline, the GK ridgeline, and the BK ridgeline.

  The horizontal axis represents R, G, and B values, and the vertical axis represents the K value.

  Here, the RK ridge line is taken up and described, but the same applies to the GK ridge line and the BK ridge line.

  The vertex of R is R = 255, and at this point, K = 0, which matches the value of K (K = 0) obtained from the vertex of R (Chroma = 255) obtained from the function shown in FIG.

Starting from this vertex of C (CMYK = (0,100,100,0)) and proceeding on the ridge line toward R-flavored K (CMYK = (0,100,100,100)) shown in FIG. The value of K decreases sequentially, and the value of K increases accordingly, reaching the interpolation start point (CMYK = (0, 100, 100, K _param )) shown in FIG. Up to this point, the surface of the print profile (see FIG. 14) is traced, and the K value satisfies the CMYK = (0, 100, 100, K) according to the R value, and has the best color matching K value. (0 ≦ K ≦ K _param ) is uniquely determined.

Proceed on the ridgeline (see FIG. 23) from the vertex of R (CMYK = (0, 100, 100, 0)) to the R taste K (CMYK = (0, 100, 100, 100)), and CMYK = (0 , 100, 100, K _param ), it moves away from the ridgeline and proceeds to CMYK = (100, 100, 100, K _max ), which is a black spot of dummy RGB. During this time, since the print profile moves away from the edge of the print profile, the value of K can take any value between the minimum value and the maximum value for each point. Therefore, here, the value between K _param and K _max follows the straight line (or curve) obtained by linear interpolation or quasi-Hermitian interpolation, and the value of K according to the decrease in R value (increase in C value). _Is increased from K _param to K _max .

When K _param and K _max are connected by linear interpolation, inversion of the K value in the middle is reliably prevented. For using quasi-Hermitian interpolation high-order polynomial, it interpolated value is also be possible to increase the inversion than K _max, where or clips the large interpolation value K _max than K _max, or inversion is confirmed In response to this, processing such as switching to linear interpolation may be performed.

In this way, the K value of each point on the RK edge starting from the vertex of R and passing through the point of CMYK = (0, 100, 100, K _param ) to (100, 100, 100, K _max ). Is required.

  Here, the RK ridgeline is taken up and described, but the same applies to the GK ridgeline and the BK ridgeline.

  FIG. 56 is a diagram showing another example of the functional form of the K value assigned to each point on the RK ridgeline, the GK ridgeline, and the BK ridgeline.

  The horizontal axis represents R, G, and B values, and the vertical axis represents the K value. Here again, the RK ridgeline will be taken up and described.

R vertices of (CMYK = (0,100,100,0)) interpolation start point shown in FIG. 24, starting from _{(CMYK = (0,100,100, K param} )) for each point to reach the This is the same as the case of FIG. 55, and the K value having the best color matching is adopted when CMYK = (0, 100, 100, K), which is uniquely determined.

As described above, until the interpolation start point (CMYK = (0, 100, 100, K _param )) reaches the black point of DummyRGB (CMYK = (100, 100, 100, K _max )), it is within the print profile. Therefore, as the K value, an arbitrary value between the minimum value and the maximum value corresponding to each point can be taken. Therefore, here, the maximum value-minimum value is referred to as the K range, and (K-minimum value) / (maximum value-minimum value) is defined as the K range ratio. Here, the interpolation start point CMYK = (0, 100, 100, K _param) and dummyRGB black point CMYK = (0,100,100, between K _param), the value of K is employed to satisfy the K range rate predetermined (e.g. K range index = 0.4) The

  Here, the RK ridgeline is taken up and described, but the same applies to the GK ridgeline and the BK ridgeline.

In the K value definition process (step (c1)) in FIG. 6, as described above, on the gray axis, the WMRY surface, the WYGC surface, the CBM surface, the RK ridgeline, the GK ridgeline, and the BK ridgeline. After the K value is assigned to the point, in the next K value calculation process (step (c2)) in FIG. 6, the K value for each point on the gray axis and each point on the edge line is defined as a boundary condition. By performing the interpolation calculation, the value of K for each surface inside the surface other than the edge of the color reproduction region of the proofer 14 and other than the gray axis is obtained. Here, specifically, a quadratic equation similar to the above-described interpolation equation K = d ₀ R ² + d ₁ G ² + d ₂ B ² + d ₃ RG + d ₄ GB + d ₅ BR + d ₆ R + d ₇ G + d ₈ B + d ₉
And d ₀ to d ₉ are calculated by using the points on the gray axis, WMRY surface, WYGC surface, CBM surface, RK ridge line, GK ridge line, and BK ridge line of the color reproduction region as sample points. . However, at this time, the sample points of R ₂ = G ₂ = B ₂ (each point on the gray axis) are calculated by weighting, for example, 1000 times the intensity. In this way, in the vicinity of the gray axis, the K value of each point on the gray axis is strongly influenced, and the K value around the gray axis is almost the same as the K value on the gray axis. By doing so, even if the gray axis of the virtual proofer 14 calculated here is slightly deviated from the gray axis of the actual printer 11 shown in FIG. = K (C) can be faithfully observed.

  In this way, for each point on the gray axis, the WMRY surface, the WYGC surface, the CBM surface, the RK ridgeline, the GK ridgeline, and the BK ridgeline in the K value definition process (step (c1)) in FIG. After K values are assigned and K values are obtained for the entire color reproduction region in the K value calculation process (step (c2)) in FIG. 6 using these as boundary conditions, each point of the color reproduction region is now obtained. By referring to the print profile 52 shown in FIG. 14 with the K value as the constraint condition, the CMYK value is assigned to each point in the color reproduction region.

  FIG. 57 is an explanatory diagram of how to obtain CMYK values corresponding to each point in the color reproduction region of dummyRGB.

FIG. 14 shows a print profile for converting CMYK values to L ^* a ^* b ^* values. Here, the print profile is referred to in the reverse direction with the K value of each point as the K constraint condition, The L ^* a ^* b ^* value at each point is converted into a CMYK value after satisfying the K value at that point. However, since there is no region of K <0 (see FIG. 15) in the print profile, the K value of the point having the K value of K <0 at the stage before referring to this print profile is K = 0. Replaced.

In the profile creation process (step (A)) of FIG. 4, the profile of the proofer 14 (proofer profile 53 (see FIG. 16)) is created as described above. That is, each point in the entire color reproduction region of the proofer 14 is assigned a dummy RBG value that depends on the proofer 14 and an L ^* a ^* b ^* value that does not depend on the proofer 14. In addition, Here, by assigning CMYK values to the entire color reproduction region of the proofer 14, a link profile 54 is created in which the dummy RBG values depending on the proofer 14 and the CMYK values depending on the printing system are associated with each other as shown in FIG. The The link profile 54 corresponds to color matching (second color conversion definition) in the color conversion apparatus 10 shown in FIG.

  FIG. 58 is a conceptual diagram showing a color conversion definition composed of a first color conversion definition and a second color conversion definition.

  Here, the first color conversion definition 351 obtained in the first color conversion definition creating process in step (B) in FIG. 4 and the second color conversion definition creating process in step (C) in FIG. 4 are obtained. Combined with the second color conversion definition 341, the RGB data for the printer (data representing coordinate points in the input RGB color space) is adapted to the CMYK data for printing (see the printing system 12 (see FIG. 1)). A color conversion definition 350 to be converted into data representing coordinate points in the CMYK color space is created. As described above, the created color conversion definition 350 is set in the color conversion device 10 shown in FIG. 1, and the color conversion definition 350 set in the color conversion device 10 is actually used in the color conversion device 10. This is used when converting RGB data for the printer 11 representing the above image into CMYK data for printing.

  The CMYK data generated by the conversion using the color conversion definition 350 has a K value suitable for the printing system 12 (that is, excellent printability), the color reproduction area of the printer 11 and the color of the printing system 12. A print image 12a that reproduces a preferable color approximate to the color of the print image 11a printed out by the printer 11 based on the RGB data for the printer 11 before the conversion is absorbed by “successfully” absorbing the difference in the reproduction area. This is CMYK data.

  In the above embodiment, the printer 11 shown in FIG. 1 is employed as the first device according to the present invention. However, the first device according to the present invention is not limited to the output device such as the printer 11, for example, an image May be an input device such as a color scanner that reads R and G and outputs image data of R, G, and B. Between the RGB data obtained by the input device and the image from which the RGB data is obtained The present invention can also be applied to the case of creating a color conversion definition that changes to CMYK data that has preferable colors and excellent printability.

  Further, in the above embodiment, the proofer 14 shown in FIG. 1 is adopted as the second device according to the present invention. However, the proofer 14 can be easily understood by replacing it with the role of the proofer in normal printing. As the second device in the present invention, any type of device can be used as long as the device is assumed to have a color reproduction region that sufficiently matches the color reproduction region of the printing system 12. May be adopted.

It is a figure which shows the system by which the color conversion definition produced by this invention is employ | adopted. 1 is an external perspective view of a personal computer that constitutes an embodiment of a color conversion definition creating apparatus of the present invention. It is a hardware block diagram of the personal computer. It is a hardware block diagram of the personal computer. It is a flowchart which shows one Embodiment of the color conversion definition preparation method of this invention. 5 is a flowchart showing a detailed flow of a profile creation process in the color conversion definition creation method shown in FIG. 4. It is a flowchart which shows one Embodiment of the profile creation method of this invention. It is a schematic block diagram of one embodiment of the color conversion definition creation program of the present invention. It is a schematic block diagram of the profile creation part which is one program part in the color conversion definition creation program shown in FIG. It is a schematic block diagram of one Embodiment of the profile creation program of this invention. It is a function block diagram of one Embodiment of the color conversion definition production apparatus of this invention. FIG. 11 is a functional configuration diagram of a profile creation unit in the color conversion definition creation device shown in FIG. 10. It is a function block diagram of one Embodiment of the profile creation apparatus of this invention. It is a conceptual diagram of a printer profile. It is a conceptual diagram of a printing profile. It is a figure which illustrates K version constraint conditions. It is created in the profile creation process of step (A) of the color conversion definition creation method of FIG. It is a conceptual diagram of the proofer profile which is a profile. FIG. 5 is a conceptual diagram of a link profile that is a profile created in a second color conversion definition creation process in step (C) of the color conversion definition creation method of FIG. 4. It is the figure which illustrated the color reproduction area of printing. It is the figure which illustrated the color reproduction area of printing. It is the figure which showed the path | route which each ridgeline followed from each vertex of R, G, B to the vertex of K vertex ((C, M, Y, K) = (100,100,100,100)). It is a figure which shows the table which defined the ridgeline which ties W and C. It is a figure which shows the table which defined the ridgeline which ties C and G. It is explanatory drawing of the definition of the ridgeline between the vertex of R and the vertex of K. It is a figure which shows the table which defined the ridgeline between the vertex of R, and the vertex of K. Is a diagram showing the relationship between K _max and K _param. It is a figure which shows the color reproduction area | region of the proofer created by tracing the color reproduction area | region of printing. It is a figure which shows the color reproduction area | region of the proofer created by tracing the color reproduction area | region of printing. It is a figure which shows the color reproduction area | region of the proofer created by tracing the color reproduction area | region of printing. It is the figure which showed the point on the ridgeline before re-association. It is the figure which showed the point on the ridgeline after re-association. It is explanatory drawing of the equal interval process using 1DLUT which inputs an accumulated color difference and outputs L ^* value. It is a conceptual diagram of the lattice point on the ridgeline before an equal interval process. It is a figure which shows the table which defined the ridgeline which connects W and C after an equal interval process. It is a figure which shows the table showing a gray axis profile. It is a conceptual diagram which shows a proofer profile. FIG. 2 is a schematic diagram of color reproduction regions of the printer and the proofer shown in FIG. 1. It is the flowchart which showed the 1st color conversion definition creation process among the color conversion definition creation methods. It is the block diagram which showed the structure of the 1st color conversion definition preparation part among the color conversion definition preparation programs. It is a functional block diagram of the 1st color conversion definition preparation part of a color conversion definition preparation apparatus. It is explanatory drawing of the 2nd process in the 2nd coordinate transformation process. It is explanatory drawing of the 1st example of the coordinate transformation in a 1st process. It is the flowchart of the 1st example. FIG. 43 is a diagram illustrating a modification of the coordinate conversion described with reference to FIGS. 41 and 42. It is explanatory drawing of the 2nd example of the coordinate transformation in a 1st process. It is the flowchart of the 2nd example. It is a figure which shows the modification of the 2nd example of the coordinate transformation demonstrated with reference to FIG. FIG. 45 is an explanatory diagram of the effect of mapping performed by combining the “compression” described with reference to FIGS. 41 and 42 and the “decompression” described with reference to FIGS. 44 and 45. It is explanatory drawing of the 3rd example of the coordinate transformation in a 1st process. It is the flowchart of the 3rd example. It is a figure which shows the modification of the 3rd example of the coordinate transformation demonstrated with reference to FIG. It is explanatory drawing of the 4th example of the coordinate transformation in a 1st process. It is the flowchart of the 4th example. FIG. 53 is a diagram illustrating a modification of the fourth example of coordinate transformation described with reference to FIGS. 51 and 52. It is the figure which showed the function form of K value allocated to each point on a WMRY surface, a WYGC surface, and a WCBM surface. It is the figure which showed an example of the functional form of K value allocated to each point on a RK ridgeline, a GK ridgeline, and a BK ridgeline. It is the figure which showed another example of the function form of K value allocated to each point on a RK ridgeline, a GK ridgeline, and a BK ridgeline. It is explanatory drawing of how to obtain | require the CMYK value corresponding to each point of the color reproduction area | region of dummyRGB. It is a conceptual diagram which shows the color conversion definition which consists of a 1st color conversion definition and a 2nd color conversion definition.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Color conversion apparatus 11 Printer 12 Printing system 14 Proofer 20 Personal computer 30 Color conversion definition creation program 31 Profile creation part 32 1st color conversion definition creation part 33 2nd color conversion definition creation part 40 Color conversion definition creation apparatus 41 Profile Creation unit 42 First color conversion definition creation unit 43 Second color conversion definition creation unit 51 Printer profile 52 Print profile 53 Proofer profile 54 Link profile 311 Color reproduction region definition unit 312 Edge profile creation unit 313 Gray axis profile creation unit 314 Profile Calculation Unit 330 Profile Creation Program 331 K Value Definition Unit 332 K Value Calculation Unit 333 K Value Constraint Condition Gain Unit 341 Second Color Conversion Definition 350 Color Conversion Definition 351 Color Conversion Definition 411 Color Current region defining unit 412 edge line profile creating unit 413 gray axis profile creating section 414 profile calculator 430 profile generator 431 K-value definition section 432 K value calculation unit 433 K value constraint utilization section

Claims (12)

Coordinate points in the color reproduction region of the first device in the first RGB color space depending on the first device that mediates between the image and the image data are used for printing color reproduction in the CMYK color space for printing. In the color conversion definition creation method for creating a color conversion definition for converting to coordinate points in the area,
Between a second RGB color space depending on a virtual second device that mediates between an image and image data, having a color reproduction area that follows the color reproduction area of printing, and a predetermined common color space A profile creation process to create a virtual device profile;
Using the device profile of the first device and the virtual device profile created in the profile creation process, a coordinate point in the color reproduction region of the first device in the first RGB color space is determined as the second device. A first color conversion definition creating process for creating a first color conversion definition for converting to a coordinate point in the color reproduction region of the second device in the RGB color space;
Create a second color conversion definition for converting the coordinate point in the color reproduction area of the second device in the second RGB color space to the coordinate point in the print color reproduction area in the CMYK color space And a second color conversion definition creation process.
The second color conversion definition creation process includes:
On the gray axis, the value of K obtained by the K plate constraint condition of printing is adopted, and the WMRY plane, WYGGCW, surrounded by ridge lines sequentially connecting W-M-R-Y-W For the WYGC plane surrounded by the sequentially connecting ridge lines and the WCBM plane surrounded by the ridge lines sequentially connecting W-C-B-M-W, a value of K ≦ 0 is used, and RK is connected. For the RK ridgeline, the GK ridgeline connecting G-K, and the BK ridgeline connecting BK, by adopting a value of K ≧ 0, the color reproduction region of the second device on the gray axis, A K value defining process for defining a value of K for each point on the WMRY surface, the WYGC surface, the WCBM surface, the RK ridgeline, the GK ridgeline, and the BK ridgeline;
By the interpolation operation using the K value defined for each point on the gray axis, the WMRY plane, the WYGC plane, the WCBM plane, the RK ridgeline, the GK ridgeline, and the BK ridgeline as the boundary condition, the second A K value calculation process for obtaining a K value of each point excluding each point where the K value is defined in the K value definition process in the entire area including the inside of the color reproduction region of the device;
A printing profile having a K value over the entire color reproduction region of the second device, which is composed of the K value defined in the K value defining process and the K value calculated in the K value calculating process, as a constraint. A color conversion definition creating method comprising: a K value constraint condition using step of creating the second color conversion definition over the entire color reproduction region by referring to FIG. The K value defining process is performed for each point on the WMRY surface, the WYGC surface, and the WCBM surface.
Chroma = Max (R, G, B) −Min (R, G, B)
However, Max (R, G, B) is the maximum value of the R, G, B values at that point,
Min (R, G, B) is the minimum value of the R, G, B values at that point.
Represents.
2. The color conversion definition creating method according to claim 1, wherein K = 0, when K becomes a maximum value, and K which becomes a negative value having a large absolute value as Chroma deviates from the maximum value.   The K value calculation process gives more weight to each point on the gray axis than each point on the WMRY plane, WYGC plane, WCBM plane, RK ridgeline, GK ridgeline, and BK ridgeline. A process of obtaining a K value of each point excluding each point where the K value is defined in the K value defining process in the entire area including the inside of the color reproduction region of the second device by interpolation calculation. The color conversion definition creating method according to claim 1. In the profile creation process, the vertices of W, C, M, Y, R, G, and B of the color reproduction area of the second device are set to the corresponding W, C, M, Y, and R of the print color reproduction area. , G, and B, and the edge line connecting each vertex of W, C, M, Y, R, G, and B of the color reproduction area of the second device corresponds to the printing color reproduction area. to match the ridge, the second for the vertices of K of the color reproduction area of a device that adopts the maximum value K _max of K of K-plate restraint condition of the printing (C, M, Y, K ) = (100, 100, 100, K _max ) and between the R, G, B vertices and the K vertices of the color reproduction region of the second device starts from the R, G, B vertices. , Up to a predetermined K value K _param (where K _param <K _max ), (C, M, Y, K) = (0, 100, 100, 100), (C, M, Y, K) = (100, 0, 100, 100), (C, M, Y, K) = (100, 100, 0, 100) at each vertex RK ridge lines that trace (C, M, Y, K) = (100, 100, 100, K _max ) that are the vertices of K away from each ridge line after tracing the respective ridge lines that are directed and reaching the value K _param 2. The color conversion definition creating method according to claim 1, further comprising a color reproduction area defining step for defining a color reproduction area of the second device by constructing a GK edge line and a BK edge line. The K value definition process is a process of assigning a value of K obtained by interpolation calculation to each point between K _param and K _max on the RK ridge line, the GK ridge line, and the BK ridge line. The color conversion definition creating method according to claim 4, wherein: In the K value definition process, for each point between K _param and K _max on the RK ridge line, the GK ridge line, and the BK ridge line, the maximum value and the minimum value that can be taken as the K value of the point 5. The color conversion definition creating method according to claim 4, wherein the method is a step of assigning a value of K which is apportioned between the values at a predetermined ratio. The profile creation process further includes:
When a plurality of points are defined at equal intervals on any one side that defines the color reproduction region of the second device in the second RGB color space, and the plurality of points are mapped to the common color space A plurality of points mapped onto the common color space on a ridge line corresponding to the one side of the ridge lines defining the color reproduction area of the second device defined in the color reproduction area defining process. And coordinate points in the second RGB color space and coordinate points in the common color space for each ridge line of the color reproduction region of the second device so that the intervals along the ridge line are equally spaced. A ridge line profile creation process for creating a ridge line profile in which
A plurality of points are defined at equal intervals on the gray axis connecting the two vertices of W and K in the color reproduction region of the second device in the second RGB color space, and these points are mapped onto the common color space. When the plurality of points mapped on the common color space are on the gray axis connecting the two vertices W and K defined in the color reproduction region defining process, and the distance along the gray axis Gray axis profiles in which the coordinate points in the second RGB color space and the coordinate points in the common color space are associated with each other with respect to the gray axis of the color reproduction region of the second device, Gray axis profile creation process to create
The edge line of the color reproduction area of the second device is obtained by performing an interpolation operation using the edge line profile created in the edge line profile creation process as a boundary condition and using the gray axis profile created in the gray axis profile creation process as a boundary condition. 5. A color conversion definition creating method according to claim 4, further comprising a profile calculation step of calculating an internal profile other than the surface and the gray axis. To convert the coordinate point in the color reproduction area of the device in the RGB color space depending on the device that mediates between the image and the image data into the coordinate point in the color reproduction area of printing in the CMYK color space for printing In the profile creation method to create the link profile of
On the gray axis, the value of K obtained by the K plate constraint condition of printing is adopted, and the WMRY plane, WYGGCW, surrounded by ridge lines sequentially connecting W-M-R-Y-W For the WYGC plane surrounded by the sequentially connecting ridge lines and the WCBM plane surrounded by the ridge lines sequentially connecting W-C-B-M-W, a value of K ≦ 0 is used, and RK is connected. For the RK ridge line, the GK ridge line connecting G-K, and the BK ridge line connecting BK, by adopting a value of K ≧ 0, the color reproduction area of the device on the gray axis, on the WMRY plane A K value defining process for defining a value of K for each point on the WYGC plane, WCBM plane, RK ridgeline, GK ridgeline, and BK ridgeline;
On the gray axis, on the WMRY surface, on the WYGC surface, on the WCBM surface, on the RK ridgeline, on the GK ridgeline, and on the BK ridgeline, interpolation is performed using the K value defined as a boundary condition for the device. A K value calculation process for obtaining a K value of each point excluding each point where the K value is defined in the K value definition process in the entire area including the inside of the color reproduction region;
The print profile is referred to using the K value over the entire color reproduction region of the device, which is composed of the K value defined in the K value definition process and the K value calculated in the K value calculation process, as a constraint. And a K value constraint condition using step of creating the link profile over the entire color reproduction region. Coordinate points in the color reproduction region of the first device in the first RGB color space depending on the first device that mediates between the image and the image data are used for printing color reproduction in the CMYK color space for printing. In a color conversion definition creation device for creating a color conversion definition for converting to a coordinate point in an area,
Between a second RGB color space depending on a virtual second device that mediates between an image and image data, having a color reproduction area that follows the color reproduction area of printing, and a predetermined common color space A profile creation unit for creating a virtual device profile;
Using the device profile of the first device and the virtual device profile created by the profile creation unit, the coordinate point in the color reproduction area of the first device in the first RGB color space is determined as the second device. A first color conversion definition creating unit for creating a first color conversion definition for converting to a coordinate point in the color reproduction region of the second device in the RGB color space;
Create a second color conversion definition for converting the coordinate point in the color reproduction area of the second device in the second RGB color space to the coordinate point in the print color reproduction area in the CMYK color space A second color conversion definition creation unit
The second color conversion definition creating unit;
On the gray axis, the value of K obtained by the K plate constraint condition of printing is adopted, and the WMRY plane, WYGGCW, surrounded by ridge lines sequentially connecting W-M-R-Y-W For the WYGC plane surrounded by the sequentially connecting ridge lines and the WCBM plane surrounded by the ridge lines sequentially connecting W-C-B-M-W, a value of K ≦ 0 is used, and RK is connected. For the RK ridgeline, the GK ridgeline connecting G-K, and the BK ridgeline connecting BK, by adopting a value of K ≧ 0, the color reproduction region of the second device on the gray axis, A K value definition unit that defines a value of K for each point on the WMRY plane, the WYGC plane, the WCBM plane, the RK ridgeline, the GK ridgeline, and the BK ridgeline;
By the interpolation operation using the K value defined for each point on the gray axis, the WMRY plane, the WYGC plane, the WCBM plane, the RK ridgeline, the GK ridgeline, and the BK ridgeline as the boundary condition, the second A K value calculation unit for obtaining a K value of each point excluding each point where the K value is defined by the K value definition unit in the entire region including the inside of the color reproduction region of the device;
A printing profile with the K value over the entire color reproduction region of the second device, which is composed of the K value defined by the K value defining unit and the K value calculated by the K value calculating unit, as a constraint. A color conversion definition creating apparatus comprising: a K value constraint condition utilization unit that creates the second color conversion definition over the entire color reproduction region by referring to FIG. To convert the coordinate point in the color reproduction area of the device in the RGB color space depending on the device that mediates between the image and the image data into the coordinate point in the color reproduction area of printing in the CMYK color space for printing In the profile creation device that creates the link profile of
On the gray axis, the value of K obtained by the K plate constraint condition of printing is adopted, and the WMRY plane, WYGGCW, surrounded by ridge lines sequentially connecting W-M-R-Y-W For the WYGC plane surrounded by the sequentially connecting ridge lines and the WCBM plane surrounded by the ridge lines sequentially connecting W-C-B-M-W, a value of K ≦ 0 is used, and RK is connected. For the RK ridge line, the GK ridge line connecting G-K, and the BK ridge line connecting BK, by adopting a value of K ≧ 0, the color reproduction area of the device on the gray axis, on the WMRY plane A K value defining unit that defines a value of K for each point on the WYGC plane, the WCBM plane, the RK ridgeline, the GK ridgeline, and the BK ridgeline;
On the gray axis, on the WMRY surface, on the WYGC surface, on the WCBM surface, on the RK ridgeline, on the GK ridgeline, and on the BK ridgeline, interpolation is performed using the K value defined as a boundary condition for the device. A K value calculation unit for obtaining a K value of each point excluding each point where the K value is defined by the K value definition unit in the entire region including the inside of the color reproduction region;
The print profile is referred to using the K value over the entire color reproduction region of the device, which is composed of the K value defined by the K value defining unit and the K value calculated by the K value calculating unit, as a constraint. And a K value constraint condition utilization unit that creates the link profile over the entire color reproduction region. The color of the first device in a first RGB color space that is executed in the information processing apparatus in which the program is executed and that depends on the first device that mediates between the image and the image data. In a color conversion definition creating program that operates as a color conversion definition creating apparatus for creating a color conversion definition for converting a coordinate point in a reproduction area to a coordinate point in a printing color reproduction area in a CMYK color space for printing,
The information processing apparatus;
Between a second RGB color space depending on a virtual second device that mediates between an image and image data, having a color reproduction area that follows the color reproduction area of printing, and a predetermined common color space A profile creation unit for creating a virtual device profile;
Using the device profile of the first device and the virtual device profile created by the profile creation unit, the coordinate point in the color reproduction area of the first device in the first RGB color space is determined as the second device. A first color conversion definition creating unit for creating a first color conversion definition for converting to a coordinate point in the color reproduction region of the second device in the RGB color space;
Create a second color conversion definition for converting the coordinate point in the color reproduction area of the second device in the second RGB color space to the coordinate point in the print color reproduction area in the CMYK color space A second color conversion definition creation unit
The second color conversion definition creating unit;
On the gray axis, the value of K obtained by the K plate constraint condition of printing is adopted, and the WMRY plane, WYGGCW, surrounded by ridge lines sequentially connecting W-M-R-Y-W For the WYGC plane surrounded by the sequentially connecting ridge lines and the WCBM plane surrounded by the ridge lines sequentially connecting W-C-B-M-W, a value of K ≦ 0 is used, and RK is connected. For the RK ridgeline, the GK ridgeline connecting G-K, and the BK ridgeline connecting BK, by adopting a value of K ≧ 0, the color reproduction region of the second device on the gray axis, A K value definition unit that defines a value of K for each point on the WMRY plane, the WYGC plane, the WCBM plane, the RK ridgeline, the GK ridgeline, and the BK ridgeline;
By the interpolation operation using the K value defined for each point on the gray axis, the WMRY plane, the WYGC plane, the WCBM plane, the RK ridgeline, the GK ridgeline, and the BK ridgeline as the boundary condition, the second A K value calculation unit for obtaining a K value of each point excluding each point where the K value is defined by the K value definition unit in the entire region including the inside of the color reproduction region of the device;
A printing profile with the K value over the entire color reproduction region of the second device, which is composed of the K value defined by the K value defining unit and the K value calculated by the K value calculating unit, as a constraint. And a color conversion definition creating device comprising: a color conversion definition creating apparatus including a K value constraint condition utilization unit that creates the second color conversion definition over the entire color reproduction region. program. The program is executed in the information processing apparatus in which the program is executed, and the information processing apparatus prints coordinate points in the color reproduction area of the device in the RGB color space depending on the device that mediates between the image and the image data. In a profile creation program that operates as a profile creation device for creating a link profile for conversion to a coordinate point in a printing color reproduction area in the CMYK color space for
The information processing apparatus;
On the gray axis, the value of K obtained by the K plate constraint condition of printing is adopted, and the WMRY plane, WYGGCW, surrounded by ridge lines sequentially connecting W-M-R-Y-W For the WYGC plane surrounded by the sequentially connecting ridge lines and the WCBM plane surrounded by the ridge lines sequentially connecting W-C-B-M-W, a value of K ≦ 0 is used, and RK is connected. For the RK ridge line, the GK ridge line connecting G-K, and the BK ridge line connecting BK, by adopting a value of K ≧ 0, the color reproduction area of the device on the gray axis, on the WMRY plane A K value defining unit that defines a value of K for each point on the WYGC plane, the WCBM plane, the RK ridgeline, the GK ridgeline, and the BK ridgeline;
On the gray axis, on the WMRY surface, on the WYGC surface, on the WCBM surface, on the RK ridgeline, on the GK ridgeline, and on the BK ridgeline, interpolation is performed using the K value defined as a boundary condition for the device. A K value calculation unit for obtaining a K value of each point excluding each point where the K value is defined by the K value definition unit in the entire region including the inside of the color reproduction region;
The print profile is referred to using the K value over the entire color reproduction region of the device, which is composed of the K value defined by the K value defining unit and the K value calculated by the K value calculating unit, as a constraint. Accordingly, the profile creation program is operated as a profile creation apparatus including a K value constraint condition utilization unit that creates the link profile over the entire color reproduction region.

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