JP2015142250A - Color conversion correspondence information creation device, method and program, and manufacturing system and manufacturing method for printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology for creating color conversion correspondence information taking granularity or gradation of an image into account.SOLUTION: A color conversion correspondence information creation device for transforming coordinate values of an input colorimetric system into ink quantities of an ink colorimetric system formed from a plurality of kinds of ink includes an initial value setting section, a smoothing/optimizing processing section and a color conversion correspondence information creating section. The smoothing/optimizing processing section determines an ink quantity of a first ink when optimizing the ink quantities, and then determines an ink quantity of any other ink than the first ink with a density lower than that of the first ink on the basis of the ink quantity of the first ink.

Description

  The present invention relates to a technique for creating color conversion correspondence information, and more particularly, to a technique for creating color conversion correspondence information using a smoothing process.

  The color conversion correspondence information is information indicating a correspondence relationship between the input color system and the output color system, and is used in a format such as a color conversion lookup table or a color conversion function, for example. The coordinate value of the input color system in the color conversion lookup table represents the position of a point in the color space of the input color system, and the coordinate value of the output color system is a point in the color space of the output color system. Represents the position. In the present specification, points in an arbitrary color space are also referred to as “color points” or “grid points”. Further, the color point represented by the input value and the color point represented by the output value registered in the color conversion lookup table are also referred to as “input grid point” and “output grid point”, respectively.

  As a technique for smoothing the arrangement of the input grid points and the output grid points of the color conversion lookup table, for example, there is a technique described in Patent Document 1 disclosed by the applicant of the present application.

JP 2009-188657 A JP2011-223345A

  In this smoothing, after the lattice point of the L * a * b * color system is moved, the optimum ink amount corresponding to the moved L * a * b * lattice point is determined.

  However, in the conventional method, each ink is handled equally when determining the ink amount. For this reason, the graininess and gradation of the image may not be improved due to the occurrence of high density ink dots.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

(1) According to one aspect of the present invention, there is provided an apparatus for creating color conversion correspondence information for converting an input color system coordinate value into an ink color system ink amount composed of a plurality of types of ink. Is done. The color conversion correspondence information creating device includes the ink table representing a color of a color point as an initial value associated with each of a plurality of input color system color points that are predetermined color points of the input color system. An initial value setting unit for setting an initial value of a color system and an initial value of a device independent color system color point that is a color point of a device independent color system representing a color of the input color system; Optimizes the smoothing process for smoothing the distribution of device-independent color system color points from the initial position and the amount of ink in the ink color system corresponding to the smoothed device-independent color system color points. And a smoothing / optimization processing unit that executes the optimization processing determined by the smoothing / optimization processing unit, and the coordinate value of the input color system based on the ink amount determined by the smoothing / optimization processing unit. A color conversion correspondence information creating unit for creating color conversion correspondence information for conversion to a color ink amount; The smoothing / optimization processing unit determines the ink amount of the first ink when optimizing the ink amount, and then, based on the ink amount of the first ink, the first ink According to this form of the color conversion correspondence information creating apparatus that determines the ink amount of the ink other than the first ink having a lower density than the first ink, the ink amount of the high-concentration ink is preferentially determined. An image with good tonality can be obtained.

(2) In the color conversion correspondence information creating apparatus according to the above aspect, the first ink may be black ink. According to the color conversion correspondence information creating apparatus of this aspect, since the ink amount of black ink is preferentially determined, an image with better granularity and gradation can be obtained.

  The present invention can be realized in various forms, for example, a color conversion correspondence information creation method and apparatus, a smoothing / optimization processing method and apparatus therefor, and color conversion correspondence information in a printing apparatus. The present invention can be realized in the form of a printing apparatus manufacturing method and manufacturing system to be incorporated, a computer program for realizing the functions of the method or apparatus, a recording medium on which the computer program is recorded, and the like.

The block diagram which shows the structure of the lookup table preparation apparatus in one Embodiment of this invention. The flowchart which shows the whole process sequence of embodiment. Explanatory drawing which shows the processing content in the case of producing a base 3D-LUT by step S100-S300 of FIG. FIG. 4 is an explanatory diagram showing a correspondence relationship between color points of an RGB color system that is an input color system and color points of an L * a * b * color system. Explanatory drawing which shows the processing content in the case of producing a base 4D-LUT by step S100-S300 of FIG. Explanatory drawing which shows the preparation method of the color correction LUT using base LUT. The figure which shows the curve of the ink amount of K ink in a lattice point position.

Embodiments of the present invention will be described in the following order.
A. Equipment configuration and overall processing procedure:
B. Ink amount search:
C. Modified example

A. Equipment configuration and overall processing procedure:
FIG. 1 is a block diagram showing a configuration of a lookup table creation device according to an embodiment of the present invention. This apparatus includes a base LUT creation module 100, a color correction LUT creation module 200, a forward model converter 300, and an LUT storage unit 400. “LUT” is an abbreviation for Lookup Table. The functions of the modules 100 and 200 and the converter 300 are realized by the computer executing a computer program stored in the memory. The LUT storage unit 400 is realized by a recording medium such as a hard disk device.

  The base LUT creation module 100 includes a smoothing processing initial value setting module 120, a smoothing processing module 130, and a table creation module 140. The smoothing processing module 130 includes a color point movement module 132, an ink amount optimization module 134, and an image quality evaluation index calculation module 136. The forward model converter 300 includes a spectral printing model converter 310 and a color calculation unit 320. The functions of these parts will be described later.

  The LUT storage unit 400 is for storing the inverse model initial LUT 410, the base 3D-LUT 510, the base 4D-LUT 520, the color correction 3D-LUT 610, the color correction 4D-LUT 620, and the like. However, LUTs other than the inverse model initial LUT 410 are created by the base LUT creation module 100 and the color correction LUT creation module 200. The base 3D-LUT 510 is a color conversion lookup table that receives an RGB color system and outputs an ink amount. On the other hand, the base 4D-LUT 520 is a color conversion lookup table that receives the CMYK color system and outputs the ink amount. “3D” and “4D” mean the number of input values. The RGB color system and CMYK color system, which are the input color systems of these base LUTs 510 and 520, are not device-dependent color systems that depend on a specific device, but are virtual sets that are set independently of a specific device. It is a color system (or abstract color system). These base LUTs 510 and 520 are used when creating the color correction LUTs 610 and 620, for example. “Base” of “base LUT” means a basis for creating a color correction LUT. The color correction LUTs 610 and 620 are lookup tables for converting a standard device-dependent color system (for example, an sRGB color system or a JAPAN COLOR 2001 color system) into an ink amount of a specific printer. The inverse model initial LUT 410 will be described later.

  FIG. 2 is a flowchart showing an overall processing procedure of the embodiment. 3A to 3C are explanatory diagrams showing processing contents when a base 3D-LUT is created by steps S100 to S300 of FIG. In step S100, a forward model converter 300 and an inverse model initial LUT 410 are prepared. Here, the “forward model” means a conversion model that converts the ink amount into a color value (colorimetric value) of the device independent color system. In contrast, the “inverse model” is a device independent color system. This means a conversion model that converts the color value of the ink into an ink amount. In the embodiment, the CIE-L * a * b * color system is used as the device independent color system. Hereinafter, the color value of the CIE-L * a * b * color system is also simply referred to as “L * a * b * value” or “Lab value”.

  As shown in FIG. 3A, the spectral printing model converter 310 that forms the preceding stage of the forward model converter 300 is configured such that a plurality of types of ink amounts are converted into spectral reflectances of color patches that are printed according to the ink amounts. Convert to R (λ). In the present specification, the term “color patch” is used in a broad sense including not only a chromatic color patch but also an achromatic color patch. In this embodiment, eight types of inks of cyan (C), magenta (M), yellow (Y), black (K), light cyan Lc, light magenta Lm, light black Lk, and ultralight black LLk can be used. A color printer is assumed, and the spectral printing model converter 310 also receives the ink amounts of these eight types of ink. However, an arbitrary ink set can be used as the plurality of types of ink used in the printer. The color calculation unit 320 calculates the color value of the L * a * b * color system from the spectral reflectance R (λ). For the calculation of the color value, a light source (for example, standard light D50) selected in advance is used as a color patch observation condition. As a method for creating the spectral printing model converter 310, for example, a method described in JP-T-2007-511175 can be employed.

  The inverse model initial LUT 410 is a look-up table in which L * a * b * values are input and ink amounts are output. The initial LUT 410 is obtained by, for example, dividing the L * a * b * space into a plurality of small cells and selecting and registering an optimum ink amount for each small cell. This selection is performed in consideration of, for example, the image quality of the color patch printed with the ink amount. In general, there are many combinations of ink amounts that reproduce a certain L * a * b * value. Therefore, in the initial LUT 410, one that selects an optimum ink amount from a desired viewpoint such as image quality is registered from among a large number of ink amount combinations that reproduce substantially the same L * a * b * value. The L * a * b * value that is an input value of the initial LUT 410 is a representative value of each small cell. On the other hand, the ink amount as the output value reproduces any L * a * b * value in the cell. Therefore, in this initial LUT 410, the L * a * b * value that is the input value and the ink amount that is the output value do not correspond exactly, and the ink amount of the output value is converted to L by the forward model converter 300. When converted into * a * b * values, a value slightly different from the input value of the initial LUT 410 is obtained. However, as the initial LUT 410, an input value and an output value that completely correspond to each other may be used. It is also possible to create a base LUT without using the initial LUT 410. As a method for creating the initial LUT 410 by selecting an optimal ink amount for each small cell, for example, the method described in the above Japanese translation of PCT publication No. 2007-511175 can be employed.

  In step S200 of FIG. 2, an initial input value for creating a base LUT is set. FIG. 3B shows an example of the configuration of the base 3D-LUT 510 and its initial input value setting. As the input values of the base 3D-LUT 510, values at substantially equal intervals predetermined as RGB values are set. Since a set of RGB values is considered to represent a point in the RGB color space, the set of RGB values is also referred to as an “input grid point”. In step S200, the initial value of the ink amount for a small number of input grid points selected in advance from among the plurality of input grid points is input by the user. It is preferable to select at least an input grid point corresponding to a vertex of a three-dimensional color solid in the RGB color space as the input grid point to which the initial input value is set. At the apex of the three-dimensional color solid, each RGB value takes the minimum value or the maximum value of the definition range. Specifically, when each RGB value is expressed by 8 bits, (R, G, B) = (0,0,0), (0,0,255), (0,255,0), (255, The initial input value of the ink amount is set for eight input grid points of (0,0), (0,255,255), (255,0,255), (255,255,0), and (255,255,255). Note that the ink amounts for the input grid points of (R, G, B) = (255, 255, 255) are all set to zero. The initial input value of the ink amount for the other input grid points is arbitrary, and is set to 0, for example. In the example of FIG. 3B, the ink amount for the input grid point of (R, G, B) = (0,0,32) is a value other than 0. This is when this LUT 510 is completed. Is the value of

  In step S300 of FIG. 2, the smoothing processing module 130 (FIG. 1) executes smoothing processing (smoothing / optimization processing) based on the initial input value set in step S200. FIG. 3C shows the processing content of step S300. On the left side of FIG. 3C, the distribution of a plurality of color points in a state before the smoothing process is indicated by double circles and white circles. These color points constitute a three-dimensional color solid CS in the L * a * b * space. The L * a * b * coordinate values of each color point are converted into L * a * b values using the forward model converter 300 (FIG. 3A) from the ink amounts at a plurality of input grid points of the base 3D-LUT 510. It is the value. As described above, in step S200, the initial input value of the ink amount is set only for some small number of input grid points. Therefore, the initial value of the ink amount for other input grid points is set from the initial input value by the smoothing process initial value setting module 120 (FIG. 1). As this initial value setting method, for example, the method described in Japanese Patent Application Laid-Open No. 2009-188657 can be used.

The three-dimensional color solid CS of the L * a * b * color system has the following eight vertices (double circle points in FIG. 3C).
Point P _K : paper black point corresponding to (R, G, B) = (0,0,0).
Point P _W : Paper white point corresponding to (R, G, B) = (255,255,255).
Point P _C : cyan point corresponding to (R, G, B) = (0,255,255).
Point P _M : Magenta point corresponding to (R, G, B) = (255,0,255).
Point P _Y : Yellow point corresponding to (R, G, B) = (255,255,0).
Point P _R : Red point corresponding to (R, G, B) = (255,0,0).
Point P _G : Green point corresponding to (R, G, B) = (0,255,0).
Point P _B : Blue point corresponding to (R, G, B) = (0,0,255).

  The right side of FIG. 3C shows the distribution of color points after the smoothing process. The smoothing process is a process of moving a plurality of color points in the L * a * b * space and smoothing the distribution of these color points at regular intervals. In the smoothing process, an optimum ink amount is also determined to reproduce the L * a * b * value of each color point after movement. When this optimum ink amount is registered as the output value of the base LUT 510, the base LUT 510 is completed.

  4A to 4C show the correspondence between the color points of the input color system (that is, the input grid points) and the color points of the L * a * b * color system. The vertices of the L * a * b * color system three-dimensional color solid CS correspond one-to-one with the vertices of the input color system three-dimensional color solid of the base LUT 510. Also, the sides (ridge lines) connecting the vertices can be considered to correspond to each other in both color solids. Each color point of the L * a * b * color system before the smoothing process is associated with each input grid point of the base LUT 510. Therefore, each color point of the L * a * b * color system after the smoothing process Are also associated with the input grid points of the base LUT 510, respectively. Note that the input grid points of the base LUT 510 are not changed by the smoothing process. The three-dimensional color solid CS of the L * a * b * color system after the smoothing process corresponds to the entire color gamut (color gamut) that can be reproduced by the ink set constituting the output color system of the base LUT 510. . Therefore, the input color system of the base LUT 510 has significance as a color system that represents the entire color gamut that can be reproduced with this ink set.

  The reason for performing the smoothing process in the L * a * b * space when creating the base LUT 510 is as follows. In the base LUT 510, there is a demand for setting an output color system ink amount so that a color gamut as large as possible can be reproduced. The color gamut that can be reproduced with a specific ink set is determined in consideration of predetermined limiting conditions such as ink duty limitation (limitation of the amount of ink that can be ejected to a certain area). On the other hand, the forward model converter 300 described above is created regardless of the reproducible color gamut without taking these restrictions into consideration. Therefore, the color gamut that can be reproduced with a specific ink set is determined by determining the possible range of color points in the L * a * b * space in consideration of limiting conditions such as ink duty limits during smoothing processing. It becomes possible to do. As an algorithm for moving the color point, for example, an algorithm described in Japanese Patent Laid-Open No. 2009-188657 can be used.

  In step S400 of FIG. 2, the table creation module 140 creates the base LUT 510 using the result of the smoothing process. In other words, the table creation module 140 outputs the optimum ink amount for reproducing the color point of the L * a * b * color system associated with each input grid point to the output of the base LUT 510 (FIG. 3C). Register as a value. In the smoothing process, in order to reduce the calculation load, it is possible to select only the color points corresponding to only a part of the input grid points of the base LUT 510 as the processing target. For example, when the RGB value interval at the input grid point of the base LUT 510 is 16, if the RGB value interval at the input grid point to be smoothed is set to 32, the load on the smoothing process can be halved. it can. In this case, the table creation module 140 determines and registers the ink amount for all the input grid points of the base LUT 510 by interpolating the smoothing processing result.

  FIGS. 5A to 5C are explanatory diagrams showing processing contents when the base 4D-LUT 520 is created by steps S100 to S300 of FIG. FIG. 5A is the same as FIG. A base 4D-LUT 520 shown in FIG. 5B is different from the base 3D-LUT 510 shown in FIG. 3B in that the input is a CMYK color system. As an initial input value of the base 4D-LUT 520, (C, M, Y, K) = (0, 0, 0, 0), (0, 0, 255, 0), (0, 255, 0, 0), (0, 255, 255) , 0), (255,0,0,0), (255,0,255,0), (255,255,0,0), (255,255,255,0), (0,0,0,255), (0,0,255,255), The initial value of the ink amount is set for 16 input grid points (0,255,0,255), (0,255,255,255), (255,0,0,255), (255,0,255,255), (255,255,0,255), (255,255,255,255) The The initial input value of the ink amount for the other input grid points is arbitrary, and is set to 0, for example.

  FIG. 5C shows a state of the smoothing process. Note that in the L * a * b * space, as the color solid corresponding to the base 4D-LUT 520, as shown at the right end of FIG. There is a three-dimensional color solid CS. In this example, a plurality of color solids CS including a color solid of K = 0 and a color solid of K = 32 are illustrated. In the present specification, these individual color solids CS are also referred to as “K layers”. This is because each color solid CS can be considered to correspond to an input layer in which the K value among the CMYK values is constant and the C, M, and Y values are variable. The plurality of color solids CS represent a dark color gamut as the K value increases. The plurality of color solids CS can be realized by determining the ink amount of the dark black ink K so that the ink amount of the dark black ink K increases as the K value of the input color system increases. As described above, the reproducible color gamut is limited by the ink duty limit value. As the ink duty limit value, two limit values are generally imposed, that is, the ink amount of each ink and the total ink amount of all inks. On the other hand, methods for reproducing dark colors include a method using achromatic ink such as dark black ink K and a method using composite black. However, since composite black has a large total ink amount, it is more likely to conflict with the ink duty limit value than dark black ink K, which is disadvantageous for reproducing dark colors. Therefore, a color solid having a large K value in the input color system and a large amount of dark black ink K is more than a color solid having a small K value in the input color system and a small amount of dark black ink K. Dark colors can be reproduced. The search for the ink amount in the smoothing process will be described later.

6A and 6B are explanatory diagrams illustrating a method for creating a color correction LUT using a base LUT. As shown in FIG. 6A, the base 3D-LUT 510 converts the RGB value into the ink amount I _j . This ink amount I _j represents the ink amounts of the eight types of ink shown in FIG. At this time, the subscript _j of the ink amount I j is 1 to 8. The converted ink amount I _j is converted into an L * a * b * value by the forward model converter 300. On the other hand, the sRGB values are converted into L * a * b * values according to a known conversion formula. The converted L * a * b * values are gamut-mapped so that the color gamut matches the color gamut of the L * a * b * values converted by the forward model converter 300. On the other hand, through the base 3D-LUT 510 and the forward model converter 300, an L * a * b * value converted from the RGB value is used as a reverse lookup table to create an inverse conversion LUT 511. The gamut-mapped L * a * b * values are converted into RGB values by the inverse conversion LUT 511. This RGB value is further converted again into the ink amount I _j by the base 3D-LUT 510. The color correction 3D-LUT 610 can be created by registering the correspondence relationship between the last ink amount I _j and the first sRGB value in the lookup table. The color correction 3D-LUT 610 is a color conversion table for converting the sRGB color system to the ink color system.

  FIG. 6B shows a method for creating the color correction 4D-LUT 620. The difference from FIG. 6A is that, instead of the 3D-LUT 510 and its inverse transformation LUT 511, the 4D-LUT 520 and its inverse transformation LUT 521 are used, and the sRGB color system is changed to an L * a * b * value. Instead of the known conversion formula for converting to ## EQU3 ## a known conversion formula for converting the JAPAN COLOR color system (shown as “jCMYK” in the figure) into L * a * b * values is used. As is well known, JAPAN COLOR is a color system composed of four colors of CMYK. In the method of FIG. 6B, when the L * a * b * value is converted into the CMYK value in the inverse transformation LUT 521, the K value of the inverse transformation LUT 521 is calculated from the K value of the first jCMYK value before the known transformation. A layer (a portion where the K value is constant) is selected. Therefore, it is possible to create a color correction 4D-LUT 620 that reflects the characteristics of the K layer in the base 4D-LUT 520.

  Normally, the base LUTs 510 and 520 are mounted on the printer driver and used for processes other than the color correction LUT creation process. However, description of other examples of use is omitted here. Hereinafter, the search for the ink amount will be sequentially described.

B. Ink amount search:
FIG. 7 is a diagram showing a curve of the ink amount of K ink at the lattice point positions. When the base 3D-LUT is processed in advance by the user before the execution of step S300 of the present embodiment, for example, (R, G, B) = (255,255,255), (255,0,0), (0,255, Similar to the curve for grid points from (0,0,255), (255,255,0), (255,0,255), (0,255,255) grid points to (0,0,0) grid points K ink generation is set. Further, when processing the base 4D-LUT, for example, (C, M, Y, K) = (0,0,0,0) to (0,0,0,255) grid points, (255,0 , 0,0) to (255,0,0,255), (0,255,0,0) to (0,255,0,255), (0,0,255,0) to (0,0,255,255) Grid points from (255,255,0,0) to (255,255,0,255), grid points from (255,0,255,0) to (255,0,255,255), (0,255,255,0) to (0,255,255,255) K ink generation similar to the curve is set for the grid points to reach.

  In the search for the ink amount by the optimization processing in the present embodiment, first, the ink amount of K ink is determined, and then the other ink amounts are determined. In determining the ink amount other than K ink, by fixing the K ink amount determined by the method described later, the one described in JP-A-2009-188657 can be modified and used.

In step S300, the K ink amount at grid points other than the grid point for which the user has specified the generation curve as described above depends on the independent variable and the relationship between the grid point and the K ink amount in the direction passing through the specified grid point. It is defined as a variable and is determined using an objective function E as shown in equation (1).

  Here, y indicates the K ink amount, y ″ indicates the second-order differential value of the K ink amount, and the subscript n indicates the position of the lattice point. The obtained K ink amount is smoothly connected. For this reason, the secondary differential value reflecting the degree of smoothness is required to be small, and at this time, the objective function is set including the secondary differential values of the adjacent lattice points n−1 and n + 1. As a result, the amount of ink can be connected smoothly even in relation to adjacent grid points.

The following formula (2) is obtained by summarizing the formula (1) for the K ink amount y.

  At this time, L, M, and N are second-order, first-order, and zero-order coefficients for yn, respectively. Further, since the expression (1) is the sum of squares, L in the expression (2) takes a positive number, and therefore the objective function E in the expression (2) is a downward convex quadratic function. Therefore, by obtaining yn that the differential value of the objective function E = 0, the desired K ink amount having a small secondary differential value can be obtained.

  The K ink amount curve specified by the user is only a lattice point connecting the vertex lattice points of the LUT lattice point group (referred to as a ridge line lattice point). The ink amount of the lattice points (referred to as the outer lattice points) is determined, and the K ink amount of the lattice points (referred to as the inner lattice points) between them is determined using the K ink amounts of those lattice points.

  After determining the K ink, the ink amount of the ink having a lower density than the K ink is determined based on the ink amount of the K ink. By doing so, the amount of high-density ink is preferentially determined, so that an image with good granularity and gradation can be obtained.

C1. Modification 1:
In the above embodiment, the CIE-L * a * b * color system is used as the device independent color system. However, other systems such as the CIE-XYZ color system and the CIE-L * u * v * color system are used. Any device independent color system can be used. However, in order to achieve smooth color reproduction, device independent color systems that are uniform color spaces such as CIE-L * a * b * color system and CIE-L * u * v * color system are used. It is preferable to use it.

C2. Variation 2:
In the above embodiment, a process using a dynamic model is employed as the smoothing process, but other types of smoothing processes may be employed. For example, it is possible to employ a smoothing process in which the distance between adjacent color points is measured and the individual distance is adjusted so as to be as close as possible to the average value.

C3. Variation 3:
In the present specification, the “ink” is used in a broad sense including not only liquid ink used in an ink jet printer and offset printing but also toner used in a laser printer. As other terms having such a broad meaning of “ink”, “coloring material”, “coloring material”, and “coloring agent” can also be used.

C4. Variation 4:
In the above embodiment, the method and apparatus for creating color conversion correspondence information such as a look-up table has been described. However, the present invention provides a printer manufacturing apparatus that includes a built-in unit that incorporates the color conversion correspondence information obtained in this way into the printing apparatus. It is also applicable to the system. The color conversion correspondence information creating apparatus that creates the color conversion correspondence information may be included in this printing apparatus manufacturing system, or may be included in another system or apparatus. The built-in part of the manufacturing system can be realized as a printer driver installer (installation program), for example.

  The present invention is not limited to the above-described embodiments and modifications, and can be realized with various configurations without departing from the spirit thereof. For example, the technical features in the embodiments and the modifications corresponding to the technical features in each embodiment described in the summary section of the invention are to solve some or all of the above-described problems, or In order to achieve part or all of the effects, replacement or combination can be performed as appropriate. Further, if the technical feature is not described as essential in the present specification, it can be deleted as appropriate.

DESCRIPTION OF SYMBOLS 100 ... Base LUT creation module 120 ... Smoothing process initial value setting module 130 ... Smoothing process module 132 ... Color point movement module 134 ... Ink quantity optimization module 136 ... Image quality evaluation index calculation module 140 ... Table creation module 200 ... Color correction LUT creation Module 300 ... Forward model converter 310 ... Spectral printing model converter 320 ... Color calculation unit 400 ... LUT storage unit 410 ... Inverse model initial LUT
510 ... Base 3D-LUT
511 ... Inverse transformation LUT
520 ... Base 4D-LUT
521 ... Inverse LUT
610: Color correction 3D-LUT
620 ... Color correction 4D-LUT

Claims (6)

A device for creating color conversion correspondence information for converting the coordinate value of an input color system into an ink amount of an ink color system composed of a plurality of types of ink,
As an initial value associated with each of a plurality of input color system color points that are predetermined color points of the input color system, an initial value of the ink color system representing the color of the color point, and the input An initial value setting unit for setting an initial value of a device independent color system color point that is a color point of a device independent color system representing a color of the color system;
A smoothing process for smoothing the distribution of the plurality of device independent color system color points from an initial position, and an amount of ink of the ink color system corresponding to the smoothed plurality of device independent color system color points A smoothing / optimization processing unit for performing optimization processing determined by optimization,
Color conversion correspondence that creates color conversion correspondence information for converting the coordinate value of the input color system into the ink amount of the ink color system based on the ink amount determined by the smoothing / optimization processing unit An information creation department;
With
The smoothing / optimization processing unit determines the ink amount of the first ink when optimizing the ink amount, and then, based on the ink amount of the first ink, more than the first ink. A color conversion correspondence information creating apparatus for determining an ink amount of ink other than the first ink having a low density. The color conversion correspondence information creation device according to claim 1,
The color conversion correspondence information creating apparatus, wherein the first ink is black ink. A method for creating color conversion correspondence information for converting the coordinate value of an input color system into an ink amount of an ink color system composed of a plurality of types of ink,
(A) As an initial value associated with each of a plurality of input color system color points that are predetermined color points of the input color system, an initial value of the ink color system that represents the color of the color point; An initial value of a device independent color system color point that is a color point of a device independent color system representing a color of the input color system; and
(B) a smoothing process for smoothing the distribution of the plurality of device independent color system color points from an initial position, and the ink color system corresponding to the plurality of device independent color system color points that have been smoothed. An optimization process for determining the amount of ink by optimization; and
(C) creating color conversion correspondence information for converting the coordinate value of the input color system into the ink amount of the ink color system based on the ink amount determined in the step (b);
With
In the step (b), when the ink amount is optimized, the ink amount of the first ink is determined, and then the density is lower than that of the first ink based on the ink amount of the first ink. A method for creating color conversion correspondence information, including a step of determining an ink amount of ink other than the first ink. Causes the computer to create color conversion correspondence information for converting the input color system coordinate values into ink color system ink amounts composed of multiple types of ink including achromatic ink and chromatic ink A program,
(A) The ink color system in which the computer represents a color of a color point as an initial value associated with each of a plurality of input color system color points that are predetermined color points of the input color system And an initial value of a device independent color system color point that is a color point of a device independent color system representing a color of the input color system, and
(B) a smoothing process in which the computer smoothes the distribution of the plurality of device independent color system color points from an initial position; and the ink corresponding to the plurality of device independent color system color points that have been smoothed An optimization process for determining the amount of color system ink by optimization, and
(C) Based on the ink amount determined in the step (b), the computer creates color conversion correspondence information for converting the coordinate value of the input color system into the ink amount of the ink color system. And a process of
Is a program for causing the computer to execute
In the step (b), when the ink amount is optimized, the ink amount of the first ink is determined, and then the density is lower than that of the first ink based on the ink amount of the first ink. A program for creating color conversion correspondence information, including a step of determining an ink amount of ink other than the first ink. A printing device manufacturing system,
A printing apparatus manufacturing system comprising a built-in unit that incorporates color conversion correspondence information created by the color conversion correspondence information creation apparatus according to claim 1 into the printing apparatus. A method of manufacturing a printing apparatus,
A method for manufacturing a printing apparatus, comprising the step of incorporating color conversion correspondence information created according to the color conversion correspondence information creation method according to claim 3 into a printing apparatus.

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