JP4921339B2 - Color processing apparatus and method - Google Patents

Description

  The present invention relates to color processing for generating a color conversion profile for converting an input signal value into an output value representing a color material amount.

  When the recording agent used in the printing apparatus is, for example, cyan, magenta, yellow, or black ink or toner, image processing for generating print data converts RGB data into CMYK data corresponding to each recording agent. Usually, a look-up table (LUT) is used for the color conversion process. That is, the contents of this table define the color conversion method, which recording agent is combined with the combination of RGB data.

  Such a color conversion processing rule is called a color conversion profile, and in particular, a color conversion profile that defines a rule for converting a combination of RGB data into CMYK data is called a color separation profile. The LUT described above is a form of this color separation profile.

  The color separation profile is desirably changed according to various printing conditions such as a combination of a printing medium and a recording agent, a printing speed and a printing quality. In other words, in order to obtain high print image quality, it is necessary to prepare one color separation profile for each printing condition. The print image quality includes items such as reproducible color gamut width and shape, graininess, gloss, color constant, gradation, and color stability.

  On the other hand, the number of printing media and printing conditions that the printing apparatus should deal with tends to increase year by year. That is, when developing a printing apparatus, it is necessary to create a large number of color separation profiles, and generation of a color separation profile with low man-hours and low costs is important.

  As a method for reducing the number of production steps and cost, it is conceivable to automatically generate a color separation profile. For example, Patent Document 1 repeatedly gives constants to the M-N variable among the M variables on the output side. For the second color signal of the remaining N variables, a printer model using Neugebauer's formula is constructed, the printer model is inverted using an iterative method such as Newton's method, and the coordinates in the desired color space are reproduced. Disclosed is a technique for obtaining a color separation profile. There is also known a method for automatically designing a color separation profile using such an inverted printer model.

  In addition, in inkjet printers, in order to reduce graininess, in addition to cyan, magenta, yellow basic colors and black recording agents (hereinafter referred to as dark color materials), gray, light cyan, light magenta, etc. A recording agent having a low concentration (hereinafter, a light color material) may be used. Good granularity can be obtained by replacing a part of the dark color material with a light color material for printing. However, the reproducible color gamut tends to narrow as the amount of light color material used increases. Also, CMYK four-color printers often do not perform 100% UCR from the viewpoint of graininess, etc., and often use low-lightness parts in color separation by using complementary colors and black ink, which also reduces the reproducible color gamut. There is a tendency. Basically, in such a printing apparatus, the color gamut width and graininess are in a trade-off relationship.

In the color processing according to the present invention, when generating a color conversion profile for converting an input signal value into an output value representing a color material amount, information including the total color material amount of grid points of the color conversion profile to be generated is included. Based on the input information, obtain a color conversion profile similar to the color conversion profile to be generated and its color gamut data, and based on the total color material amount, vertex grid points of the acquired color conversion profile The output value of the vertex grid point of the color conversion profile to be generated is determined from the output value of the color, the color value reproduced by the output value of the determined vertex grid point is predicted, and the color of the predicted vertex grid point Before setting the color value of the intermediate grid point located between the vertex grid points of the color conversion profile to be generated based on the value and the color gamut data, and reproducing the color value of the set intermediate grid point It determines the output values of the intermediate grid points, from the output value of the vertex grid points and the intermediate grid points, and calculates the output value of each grid point of the color conversion profile to be the product.

  The method of Patent Document 1 can obtain a color separation value that reproduces desired coordinates on a color space by repeatedly giving a constant to a part of the second color signal. However, the amount of the recording agent cannot be optimized in consideration of the graininess, and there is a fear that the graininess is partially deteriorated in the printed matter and a sufficiently wide color gamut may not be obtained.

  Patent Document 2 discloses a method of constructing a printer model that estimates image quality in the same manner as reproduced colors, and simultaneously evaluating reproduced colors, graininess, and moire, and automatically designing a color separation profile. According to the technique of Patent Document 2, it is possible to determine in advance the black amount for obtaining a suitable image quality. However, for the reason that the measurement man-hour of the graininess is very large compared to the color measurement, the construction of the printer model for predicting the image quality itself requires an enormous man-hour and it is difficult to reduce the man-hours.

Japanese Patent No. 3174509 JP2000-078418

  An object of the present invention is to generate a color conversion profile in consideration of a color gamut and other image quality items with a low man-hour.

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

  In the color processing according to the present invention, when generating a color conversion profile for converting an input signal value into an output value representing a color material amount, information including the total color material amount of grid points of the color conversion profile to be generated is included. Based on the input information, obtain a color conversion profile similar to the color conversion profile to be generated and its color gamut data, and based on the total color material amount, vertex grid points of the acquired color conversion profile The output value of the vertex grid point of the color conversion profile to be generated is determined from the output value of the color, the color value reproduced by the output value of the determined vertex grid point is predicted, and the color of the predicted vertex grid point Before setting the color value of the intermediate grid point located between the vertex grid points of the color conversion profile to be generated based on the value and the color gamut data, and reproducing the color value of the set intermediate grid point It determines the output values of the intermediate grid points, from the output value of the vertex grid points and the intermediate grid points, and calculates the output values of the grid points of the color conversion profile to be the product.

  According to the present invention, it is possible to generate a color conversion profile in consideration of the color gamut and other image quality items with low man-hours.

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

[Device configuration]
FIG. 1 is a block diagram illustrating a configuration example of a printing system according to an embodiment, which includes an inkjet recording type printer 102 and a computer (host device) 101 that functions as an image processing apparatus.

Host Device An application program (AP) 104 runs on the operating system (OS) of the host device 101. The AP 104 displays a user interface (UI) on a monitor 1209 described later. The user operates the UI to input image data to the host device 101.

  For example, JPEG format image data captured by a digital camera recorded on a memory card is input via a memory card reader. Further, TIFF format image data read by the scanner can be input via a serial bus 1211 (described later) such as USB, or image data recorded on a CD-ROM can be input via a disk drive. Of course, image data may be input from a server or a Web site on the network 1210 described later.

  When image data is input, the AP 104 displays an image represented by the image data on the UI. The user operates the UI to edit and process the image and instruct printing. In response to the print instruction, the AP 104 (or OS) passes the image data converted into, for example, sRGB standard data (8 bits for each color) to the printer driver 103 operating on the OS.

  The printer driver 103 executes color matching processing 105 and performs color gamut mapping on the input image data. In other words, the color matching process 105 uses the three-dimensional LUT (3DLUT) that indicates the relationship between the color gamut that can reproduce the image data of the sRGB standard and the color gamut that the printer 102 can reproduce, to the sRGB data for the printer. Convert to RGB data. In the following description, the color gamut in which image data of the sRGB standard can be reproduced may be referred to as the sRGB color gamut, and the color gamut in which the printer 102 can be reproduced is referred to as the printer color gamut.

  Next, the printer driver 103 executes a color separation process 106 to separate the color data into RGB data CMYK data (each color is 8 bits) subjected to color gamut mapping. As in the color matching process 105, 3DLUT and interpolation are used for the color separation process.

  Next, the printer driver 103 executes gamma correction 107 to correct (gamma correction) the gradation value for each color data of the CMYK data. Specifically, a conversion process for associating each color data with the gradation characteristics of the printer 102 is performed using a one-dimensional LUT (1DLUT) corresponding to the gradation characteristics of each color material of the printer 102.

  Next, the printer driver 103 executes halftoning 108, and converts (quantizes) 8-bit color data into 4-bit color data using, for example, an error diffusion method. This 4-bit data is index data representing a dot arrangement pattern in the printer 102.

  Next, the printer driver 103 executes print data generation 109, adds print control information to the 4-bit index data, and generates print data.

  FIG. 2 is a block diagram illustrating a configuration example of the host apparatus 101.

  The microprocessor (CPU) 1201 executes programs such as the OS, the AP 104, and the printer driver 103, using the random access memory (RAM) 1202 as a work memory. Note that programs such as the OS, AP 104, and printer driver 103 are stored in a read-only memory (ROM) 1203 and a hard disk drive (HDD) 1204.

  The CPU 1201 controls the serial bus interface (I / F) 1206 and the network interface card (NIC) 1207 via the system bus 1205 and inputs / outputs various data via the serial bus 1211 and the network 1210. Further, a UI or the like is displayed on the monitor 1209 via the video card 1208.

Printer The printer 102 performs dot placement processing 110 and mask processing 111 on each CMYK print data input from the host device 101. The dot arrangement processing 110 arranges dots according to 4-bit index data (gradation value information) for each pixel of the print image (hereinafter, print pixel). In other words, a dot pattern corresponding to the gradation value represented by 4-bit data is assigned to each print pixel, and on / off of each dot corresponding to a plurality of cells of the print pixel is defined, and '1' or '0' for each cell Dispose data for '.

  A mask process 111 performs a mask process on the ejection data. That is, in order to complete recording of a scanning area (hereinafter referred to as a band) having a predetermined width in the sub-scanning direction by scanning the recording head 113 a plurality of times, the ejection data is masked with a mask corresponding to each scanning, Scan ejection data is generated. C, M, Y, and K ejection data for each scan are sent to the head drive circuit 112 at an appropriate timing. The head driving circuit 112 drives the recording head 113 so as to eject each color material according to the ejection data.

  The dot arrangement process and the mask process are executed under the control of the CPU that constitutes the control unit of the printer 102 using a dedicated hardware circuit. Of course, the CPU of the printer 102 may perform dot arrangement processing and mask processing, or the printer driver 103 of the host device 101 may perform dot arrangement processing and mask processing.

  In this embodiment, the pixel is the smallest unit capable of gradation expression, and is the minimum of multi-value data image processing (color matching processing 105, color separation processing 106, gamma correction 107, halftoning 108, etc.). Unit data. Further, the print pixels in the print data generation 109 and the dot arrangement process 110 correspond to a 4 × 4 cell dot pattern. That is, a cell is the smallest unit in which dot on / off can be defined.

  The image data in the color matching process 105, the color separation process 106, and the gamma correction 107 represents a set of pixels, and each pixel is represented by RGB or CMYK data having a gradation value of 8 bits for each color, for example. Furthermore, by halftoning 108, CMYK data of 8 bits for each color is converted into index data having a gradation value of 4 bits for each color.

[Generate color separation profile]
FIG. 3 is a block diagram illustrating a configuration example of a device for generating a color separation profile in the present embodiment, which is realized by the CPU 1201 executing a color separation profile generation program.

Color separation profile DB
The color separation profile database (DB) 201 stored in HDD1204 etc. stores multiple existing color separation profiles (3DLUT) optimized under various conditions and a gamma correction table (1DLUT) corresponding to the color separation profile. To do. Furthermore, color gamut data reproducible by these LUTs is stored.

  The color separation profile includes a 3DLUT describing the CMYK value after color separation for the input RGB value and an interpolation calculation unit. The interpolation calculation unit of this embodiment is common to each color separation profile. Therefore, the generation of the color separation profile in this embodiment is synonymous with the generation of 3DLUT.

Color Conversion Unit The color conversion unit 209 includes a printer model unit 210 and a printer model inversion unit 211, and provides a mutual conversion function between the CMYK data and the color coordinate value Lab of the color system. The printer model unit 210 predicts a color value (reproduced color value) Lab that is reproduced when CMYK data is printed under the printing conditions of the color separation profile, using the Neugebauer equation.

  As long as it falls within the target man-hours, instead of the normal Neugebauer equation, a cellized Neugebauer equation in which the color material space is subdivided into a large number of cells to improve accuracy may be used. Of course, the printer model may be constructed not only by Neugebauer's equation but also by other color prediction methods. Further, the printer model unit 210 may predict not only the color value Lab but also various image quality evaluation items.

  However, since the purpose is to reduce the man-hours in the generation of the color separation profile (construction of the printer model), the printer model is constructed by evaluating the range within the target man-hours. For example, CII, which is an evaluation value of color constant, can be calculated from the spectral reflectance characteristics obtained in the process of calculating the Lab value, and it is preferable to use CII for evaluation of the printer model.

  The printer model inversion unit 211 repeatedly executes the printer model unit 210 by Newton's iterative method to converge the solution, thereby predicting CMYK data that can reproduce Lab values under the color separation profile printing conditions. However, since the number of dimensions of the CMYK data that is the solution is higher than the number of dimensions of the Lab value that is the input, the solution may not converge uniquely. In this embodiment, the remaining three CMYK variables are obtained by subtracting the three CMYK variables from the preset total color material amount. Accordingly, the input and output can be substantially made into three variables, and the printer model can be inverted by an iterative method.

  The printer model inversion method is not limited to Newton's iterative method, and various optimization methods and search methods can be applied. For example, a simplex method or a particle swarm optimization method may be used.

Profile generation unit The profile generation unit 202 generates a color separation profile in accordance with a user input from the generation condition input unit 203 (UI provided by the CPU 1201). The user operates the generation condition input unit 203 to input various conditions necessary for generating the color separation profile. In this embodiment, the maximum value of the total color material amount at each grid point of the color separation profile (3DLUT), the information of the gamma correction table corresponding to the color separation profile to be generated, and the target print medium of the color separation profile to be generated Enter information indicating the type of

  The vertex color separation determination unit 204 searches for an existing color separation profile from the color separation profile DB 201 based on the maximum value of the total color material amount that is the generation condition and the type of print medium, and acquires the 3DLUT data. The color separation profile to be searched is a color separation profile having printing conditions similar to the maximum value of the total color material amount, which is a generation condition, and the type of printing medium. When a plurality of similar color separation profiles are detected, for example, one color separation profile is selected in consideration of the type of printing medium, the difference in the maximum value of the total color material amount, and the type of gamma correction table.

  The color separation profile stored in the color separation profile DB 201 is desirably searchable by various condition settings, but a method in which the user directly designates the color separation profile in the generation condition input unit 203 may be used. In addition, the user may specify a color separation profile and color gamut data existing in a server outside the color separation profile DB 201 by operating the generation condition input unit 203.

If the maximum value of the total color material amount of the acquired 3DLUT data is different from the maximum value of the total color material amount of the generation condition, the vertex color separation determination unit 204 matches the maximum value of the total color material amount of the generation condition. Adjust the color separation value (output value) of the 3DLUT vertex grid points (hereinafter referred to as vertices). The 3DLUT vertices indicate eight vertices in which at least one of RGB values as input values has a minimum value of 0 or a maximum value of 255. Hereinafter, these eight vertices are called as follows.
K point (R, G, B) = (0, 0, 0),
R point (R, G, B) = (255, 0, 0),
G point (R, G, B) = (0, 255, 0),
B point (R, G, B) = (0, 0, 255),
C point (R, G, B) = (0, 255, 255),
M point (R, G, B) = (255, 0, 255),
Y point (R, G, B) = (0, 0, 255),
W point (R, G, B) = (255, 255, 255)

  The vertex reproduction color prediction unit 205 causes the printer model unit 210 to calculate a reproduction color value Lab (target color) for the eight vertex color separation values adjusted by the vertex color separation determination unit 204.

  The grid point target color determination unit 206 uses the eight vertex target values and the existing color separation profile color gamut data acquired from the color separation profile DB 201 to generate contour lines and gray lines for the color separation profile (3DLUT) to be generated. A target color for each corresponding grid point is determined. Note that the outer surface of 3DLUT corresponds to the boundary of the color gamut.

  To determine the target color, select two grid points (both end points) for which the target color or color separation value has already been determined, and select the target color of the intermediate grid point (hereinafter referred to as the intermediate point) located between the end points. decide. First, the reproduction color values of the grid points of the existing color separation profile corresponding to the grid points of the end points and the intermediate points are extracted from the color gamut data of the existing color separation profile. That is, the reproduction color value of the grid point having the same input value (RGB value) as the end point and the intermediate point is acquired.

  Next, the printer model unit 210 applies reproduced and color values corresponding to both end points and intermediate points to the reproduced color values corresponding to both end points and intermediate points by applying the movement / deformation described later in any order and any number of times. The reproduction color value is adjusted so as to match the calculated target color. Then, the reproduced color value of the adjusted intermediate point is set to the target color of the intermediate point.

The adjustment of the reproduction color value corresponding to each point (both end points and intermediate points) is performed the following movement / deformation an arbitrary number of times on the curve represented by the arrangement of the reproduction color values.
(1) Translation in Lab space
(2) Expansion and contraction in the L-axis direction, maintaining the relative spacing of the lightness value L of each point,
(3) Expansion and contraction in the C-axis direction, maintaining the relative spacing of the saturation value C of each point,
(4) Expansion and contraction in the H-axis direction, maintaining the relative spacing of the hue value H of each point,
(5) Rotation around the L axis while maintaining the relative position of each point

  By the above adjustment, the target colors of the color separation profile having the color gamut boundary similar to the shape of the color gamut boundary of the existing color separation profile can be determined while maintaining the target colors of both end points. Of course, the reproduction color value adjustment method is not limited to the above as long as the target color of the color separation profile having a color gamut boundary similar to the shape of the color gamut boundary of the existing color separation profile can be generated. .

  FIG. 4 is a diagram showing adjustment on the LC plane for determining a target color between points C and K of a new color separation profile. It is assumed that the target colors of the C point 304 and the K point 303 are obtained by the vertex reproduction color prediction unit 205.

  The grid point target color determination unit 206 calculates the reproduction color values of the C point 301 and the K point 302 corresponding to the C point 304 and the K point 303 and the intermediate point between CKs from the color gamut data of the existing color separation profile. A corresponding reproduction color curve locus (curve) 305 indicated by a solid line is acquired. Next, the grid point target color determination unit 206 performs the above transformation / movement on the curve 305 connecting the C point 301 and the K point 302 any number of times, so that the C point 301 becomes the C point 304 and the K point 302 becomes the K point. The curve 305 is deformed and moved so as to match 303. A curve 306 indicated by a broken line in FIG. 4 indicates a target color at an intermediate point between the C point 304 and the K point 303 after adjustment.

  The grid point target color determination unit 206 repeats the above adjustment based on the color separation values of the eight vertices of the color separation profile (3DLUT) to be generated, and sets the target colors of all grid points on the outer surface of the 3DLUT and the gray line. decide.

  The lattice point color separation determination unit 207 determines the color separation value CMYK of the lattice point for which the lattice point target color determination unit 206 has determined the target color by the printer model inversion unit 211. Further, the lattice point color separation determination unit 207 calculates the color separation value of each lattice point inside the 3DLUT from the color separation value of each lattice point on the outer shell surface of the 3DLUT and the gray line by interpolation.

  Note that the determination of the color separation value of the grid point in the 3DLUT may be performed by determining the target color of the grid point by the grid point target color determination unit 206 and determining the color separation value by using the printer model inversion unit 211. . In addition, the target color is determined for the grid points on the diagonal lines of each side of the 3DLUT and the outer surface, the color separation value is determined using the printer model inversion unit 211, and the remaining lattice points on the outer surface and the lattice points in the 3DLUT These color separation values may be calculated by interpolation. Whichever method is used, the shape of the color gamut boundary is optimized by the color gamut shape of the existing color separation profile.

  The profile output unit 208 outputs the 3DLUT data determined by the grid point color separation determination unit 207 to a destination specified by the user as a color separation profile described in a predetermined format. The output destination of the color separation profile follows the user instruction, but at the same time, the generated color separation profile may be registered in the color separation profile DB 201.

  In this way, by referring to the existing color separation profile and determining the target color of each grid point of the generated color separation profile, the color separation profile considering the shape of the color gamut and other image quality items can be reduced in man-hours. Can be generated. That is, a new color separation profile can be generated by inheriting the characteristics of the image quality item of the existing color separation profile.

  In other words, a new color separation profile with a color gamut shape similar to that of the existing color separation profile can be generated, and if the printing conditions such as color materials and print media are close enough, the existing color separation profile A color separation profile having substantially the same reproduction characteristics can be obtained. Therefore, by using an existing color separation profile in which the balance between the color gamut and other image quality items is sufficiently optimized, a color separation profile having good reproduction characteristics can be generated without increasing man-hours. It becomes possible to do.

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

  In the following, generation of a color separation profile for a printer that uses a total of seven color materials, that is, light cyan photocyan Lc, photomagenta Pm, and gray Gy in addition to CMYK will be described. The configuration of the apparatus is the same as that of the first embodiment, but the color separation process is extended to generate data corresponding to the seven color materials. In addition, the color conversion unit 209 is also expanded to correspond to seven color materials.

  As described above, when the number of dimensions of the output signal is higher than the number of dimensions of the input signal, there is a problem that the solution of the inverted printer model (printer model inversion unit 211) does not uniquely converge. The output value of the reversal printer model in Example 2 is CMYKLcLmGy, and since the total color material amount is set, it is substantially a 6-dimensional output, and is a unique solution for a 3-dimensional input value (Lab value). Can't get. Therefore, it is necessary to give some value to the three values among the output values of the reverse printer model, and to drop the solution space to the same three dimensions as the input values of the reverse printer model.

  Prior to inputting the Lab value to the printer model reversing unit 211, the grid point color separation determination unit 207 according to the second embodiment selects a color material that gives a fixed value and gives it based on the color separation value of an existing color separation profile. Set a fixed value.

  First, 0 is set to the color separation value of the color material (output value = 0) that is not used at the grid point of the existing color separation profile corresponding to the intermediate grid point. If the remaining color material is five colors or more (that is, four or more colors), the output value of the dark color material (C, M, K) of the existing color separation profile is evaluated. Then, a fixed value is set for the color separation values of the light color materials Lc, Lm, and Gy corresponding to the dark color material whose output value is greater than or equal to the predetermined value (threshold value or more), and color separation of the dark color material whose output value is less than the predetermined value Set a fixed value for the value.

  The fixed value given as the color separation value is adjusted by adjusting the color separation value of the existing color separation profile so that the color separation value does not change abruptly compared to the neighboring grid points for which the color separation value has already been determined. Set. For this reason, it is desirable that the fixed value is not set for each grid point, but fixed values for a plurality of grid points within a predetermined range are set collectively. For example, by setting a fixed value for a part or all of the end points and intermediate points selected by the grid point target color determination unit 206, the occurrence of jumps in color separation values between the end points can be suppressed. be able to.

  Through the above processing, the lattice point color separation determination unit 207 acquires color separation values that can be reproduced by the printer model inversion unit 211. In other words, the color separation profile can be generated by setting a fixed value so as to inherit the color separation characteristics of the existing color separation profile.

  In this manner, a new color separation profile can be generated that inherits the characteristics of the image quality items of the existing color separation profile for a printer that uses color materials of five colors or more.

[Modification]
In the above, an example in which CIELab is used for the color system has been described, but other color systems may be used. For example, CIEXYZ, CIELuv, CIECAM02, etc. may be used. Further, the input signal is not limited to sRGB, and it is also possible to generate a color separation profile that outputs a color separation value indicating a color material amount of five or more colors by inputting a CMYK signal.

  In addition, the printer recording method may be any method that uses a plurality of color materials, and may be any printing method that involves making a plate for each color material. Ink jet method, electrophotographic method, thermal transfer method, dot impact method A recording method that does not involve plate making may be used. In the ink jet system, a serial type that scans the recording head vertically and horizontally with respect to the recording area may be used, or a line head type that scans only in one direction by arranging recording nozzles in accordance with the width of the recording area may be used.

  Further, a database of color separation profiles and / or software for generating a color separation profile may be installed in a server, and the server may generate a color separation profile by an operation from a client.

[Other embodiments]
Note that the present invention can be applied to a system composed of a plurality of devices (for example, a computer, an interface device, a reader, a printer, etc.), or a device (for example, a copier, a facsimile machine, a control device) composed of a single device. Etc.).

  Another object of the present invention is to supply a storage medium storing a computer program for realizing the functions of the above-described embodiments to a system or apparatus, and the computer (CPU or MPU) of the system or apparatus executes the computer program. But it is achieved. In this case, the software read from the storage medium itself realizes the functions of the above embodiments, and the computer program and the computer-readable storage medium storing the computer program constitute the present invention. .

  Further, the above functions are not only realized by the execution of the computer program. That is, according to the instruction of the computer program, the operating system (OS) and / or the first, second, third,... This includes the case where the above function is realized.

  The computer program may be written in a memory of a device such as a function expansion card or unit connected to the computer. That is, it includes the case where the CPU of the first, second, third,... Device performs part or all of the actual processing according to the instructions of the computer program, thereby realizing the above functions.

  When the present invention is applied to the storage medium, the storage medium stores a computer program corresponding to or related to the flowchart described above.

A block diagram showing a configuration example of a printing system of an embodiment, Block diagram showing a configuration example of a host device, FIG. 2 is a block diagram illustrating a configuration example of an apparatus for generating a color separation profile according to an embodiment. It is a figure which shows the adjustment which determines the target color between C point-K point of a new color separation profile on LC plane.

Claims (7)

A color processing device that generates a color conversion profile for converting an input signal value into an output value representing a color material amount,
An input means for inputting information including the total color material amount of grid points of the color conversion profile to be generated;
An acquisition means for acquiring a color conversion profile similar to the color conversion profile to be generated and its color gamut data based on the input information;
Determining means for determining an output value of a vertex grid point of the color conversion profile to be generated from an output value of a vertex grid point of the acquired color conversion profile based on the total color material amount;
Predicting means for predicting a color value reproduced by the output value of the determined vertex grid point;
Setting means for setting a color value of an intermediate lattice point located between the vertex lattice points of the color conversion profile to be generated based on the color value of the predicted vertex lattice point and the color gamut data;
The output value of the intermediate grid point that reproduces the color value of the set intermediate grid point is determined, and the output of each grid point of the color conversion profile to be generated from the output value of the vertex grid point and the intermediate grid point A color processing apparatus comprising: calculation means for calculating a value.   The setting means sets the color value of the intermediate grid point so that the color gamut shape of the color conversion profile to be generated is similar to the color gamut shape of the acquired color conversion profile. Item 2. A color processing apparatus according to Item 1.   The calculation means reduces the number of dimensions of the output value using the total color material amount, and determines an output value that reproduces the color value of the intermediate grid point by an iterative method. The color processing apparatus according to claim 1 or 2. The calculation means sets the output value of the grid point of the acquired color conversion profile by setting 0 as the output value of the intermediate grid point corresponding to the color material whose grid point output value of the acquired color conversion profile is 0 Is set to a light color material corresponding to a dark color material having a predetermined value or more and an output value of the intermediate grid point corresponding to the dark color material less than the predetermined value, and then the total color material amount is used. 3. The color processing apparatus according to claim 1, wherein the number of dimensions of the output value is reduced and an output value for reproducing the color value of the intermediate grid point is determined by an iterative method.   The calculation means calculates an output value of a grid point located on an outer surface of a color gamut of the color conversion profile to be generated based on output values of the vertex grid point and the intermediate grid point. 5. The color processing apparatus according to any one of claims 1 to 4. A color processing method of a color processing apparatus that includes an input unit, an acquisition unit, a determination unit, a prediction unit, a setting unit, and a calculation unit, and generates a color conversion profile that converts an input signal value into an output value representing a color material amount. There,
The input means inputs information including the total color material amount of grid points of the color conversion profile to be generated,
The acquisition means acquires a color conversion profile similar to the color conversion profile to be generated and its color gamut data based on the input information,
The determining means determines the output value of the vertex grid point of the color conversion profile to be generated from the output value of the vertex grid point of the acquired color conversion profile based on the total color material amount,
The predicting means predicts a color value reproduced by an output value of the determined vertex grid point;
The setting means sets a color value of an intermediate grid point located between the vertex grid points of the color conversion profile to be generated based on the color value of the predicted vertex grid point and the color gamut data,
The calculation means determines an output value of the intermediate grid point that reproduces the color value of the set intermediate grid point, and determines the color conversion profile to be generated from the output value of the vertex grid point and the intermediate grid point. A color processing method characterized by calculating an output value of each grid point. Program characterized Rukoto to function as each unit of a color processing apparatus according to computer claims 1 to any one of claims 5.

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