JP2002365133A - Method and device for calculating color gamut of coloring material, method and device for determining color regeneration, and method and device for calculating blending ratio of coloring material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly precise method of calculating a color gamut of a coloring material compared with a conventional method, a color generation determining method using the method, and a coloring material blending ratio calculating method using the method, so as to solve technical difficulty in selection of the coloring material in a color matching process. SOLUTION: In the calculation of the color gamut allowing reproduction by combination of the coloring materials, the method of calculating the color gamut of the coloring material comprises a process for measuring a spectral transmission factor of a coloring material monochrome in plural stages of coloring material concentrations, a process for preparing a large number of predicted optical concentrations in combination of the various coloring material concentrations in combination of the some coloring materials based on a relational expression 'coloring material concentration-optical concentration' found by the Lambert-Beer's expression, using the measured value hereinbefore, a process for calculating the spectral transmission factor using the Lambert-Beer's expression based on the optical concentration, and a process for calculating the color gamut of the coloring material expressed by a three- dimensional color space based on the large number of spectral transmission factors calculated hereinbefore. The present invention provides also the color generation determining method and the coloring material blending ratio calculating method, using the color gamut calculating method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color matching process for ink and dyeing, and more particularly to a computer color matching (hereinafter abbreviated as CCM) for automatically performing color matching using a computer. is there. This CCM also particularly relates to a method of calculating a color gamut that can be reproduced by a combination of various color materials used for color matching, and a method of determining a combination of color materials used for color matching.

[0002]

2. Description of the Related Art Heretofore, for color matching of colored bodies such as paints, inks, plastics, etc., a skilled toning professional has performed selection of a color material to be used and creation of a desired color using the selected color material. In such a toning operation, an expert who has performed an enormous number of tonings selects a reproducible coloring material based on many years of experience, and performs toning. Because inexperienced toners are vague about the reproducible color gamut due to the combination of color materials they possess, and there are many unnecessary acts of toning in combinations that are not possible to match color in practice. Because it is repeated.

[0003] In recent years, CCMs that automatically calculate the blending of color materials have become widespread due to the development of computers. However, the selection of the coloring materials is also performed by an expert or the blending calculation is performed for all combinations of the coloring materials. Is the mainstream method. This is because it is difficult for a computer to select a color material that reproduces a desired color. In order to select a color material, it is necessary to calculate a color gamut based on the combination of the color materials. To create this color gamut, for example, at least several combinations such as 10% of yellow, 10% of magenta, and 40% of cyan are required. It was necessary to create more than a hundred combinations and create a look-up table. However, if there is no easy way to obtain color data of hundreds of mixed colors as in the case of a printer profile maker, there is no other way but to create each color by hand, and it is extremely inefficient to create the color gamut of color materials. It was realistic.

Therefore, there has been no method for selecting a color material with the help of a skilled person or performing CCM calculation for all combinations of the color materials. However, there are more than 100 combinations for selecting three types of color materials from only a dozen or so types of color materials and performing color matching, and a large calculation load is required to perform CCM calculation with all of the combinations. Had become.

From such a background, for example, Japanese Patent Application Laid-Open No.
As disclosed in Japanese Patent No. 4440, a method has been developed which can determine the color gamut of a color material relatively easily and determine whether or not a desired color can be reproduced, as compared with a normal color gamut calculation method. However, in the determination by these conventional methods, since the color gamut calculation method is performed using only the a ^* b ^* values of the uniform color space CIELAB, the accuracy itself has been questioned.

[0006]

Normally, in grasping the color gamut of a color material, it is necessary to calculate a color gamut using a three-dimensional uniform color space such as CIELAB and to reproduce a desired color with the selected color material. Judge. However, Japanese Patent Application Laid-Open No. 8-944
The color gamut calculation method such as by 40 JP, target color using the color gamut of two-dimensional determined from a ^* b ^* value or hue and saturation values of the maximum density of each color material used for color matching of a ^* b ^* Because it is a method to determine whether the value is within the color gamut,
L ^* value, that is, lightness was not taken into account, and the accuracy itself was questioned. This is because, for example, when the L ^* value is large, the reproducible a ^* b ^* color gamut is smaller than when the L ^* value is small, and when the L ^* value of the target color is large, a color material that cannot actually be reproduced is used. There is a drawback of choosing. That is, L
^{* It} is not possible to judge whether reproducibility is possible in the value direction, and problems remain in terms of accuracy.

SUMMARY OF THE INVENTION The present invention has been made to solve the technical difficulties in selecting a color material in the above-described color matching process, and a method of calculating a color material color gamut with higher accuracy than the conventional method and the use thereof. It is an object of the present invention to provide a color reproduction determination method and a color material mixture ratio calculation method.

[0008]

A first aspect of the present invention for achieving the above object is to calculate a color gamut which can be reproduced by a combination of color materials. 1. A step of measuring or preparing the spectral transmittance of the color material in a single color for several levels of the color material density from the minimum density to the maximum density; Using the measured values, a large number of predicted optical densities of various color material density combinations in a certain color material combination are created from the relational expression “color material density-optical density” obtained from the Lambert-Beer equation. Process, 3. 3. calculating the spectral transmittance from the optical density using the Lambert-Beer equation; Calculating a color gamut represented in a three-dimensional color space from the calculated plurality of spectral transmittances.

According to a second aspect of the present invention, there is provided a method for calculating a color gamut which can be reproduced by a combination of color materials. 1. A step of measuring or preparing the spectral reflectance of a color material in a single color for several levels of color material density from a minimum density to a maximum density; From the relational expression “colorant density-scattering absorption coefficient” obtained from the Kubelka-Munk equation using the measured values, a number of predicted scattering absorption coefficients of various combinations of colorant concentrations in a certain coloring material combination are calculated. 2. the process of creating; 3. calculating the spectral reflectance from the scattering coefficient using the Kubelka-Munk equation; Calculating a color gamut expressed in a three-dimensional color space from the plurality of calculated spectral reflectances.

According to a third aspect of the present invention, there is provided a method for calculating a color gamut which can be reproduced by a combination of color materials. 1. A step of measuring or preparing the spectral transmittance and spectral reflectance of a single color of the color material in several steps from the minimum density to the maximum density. From the relational expression “colorant density-scattering absorption coefficient” obtained from the Kubelka-Munk equation using the measured values, a number of predicted scattering absorption coefficients of various combinations of colorant concentrations in a certain coloring material combination are calculated. 2. the process of creating; 3. calculating the spectral reflectance from the scattering coefficient using the Kubelka-Munk equation; Calculating a color gamut expressed in a three-dimensional color space from the plurality of calculated spectral reflectances.

Further, a fourth invention of the present invention relates to a method for judging whether color reproduction is possible or not. 1. a step of measuring a target color and calculating a value in a three-dimensional color space; At least a step of determining whether a color material gamut obtained by the color material gamut calculation method according to any one of claims 1 to 3 includes a value of a three-dimensional color space of a target color. Is a color reproduction determination method characterized by the following.

According to a fifth aspect of the present invention, a computer color matching is performed using a combination of color materials reproducible by the color reproduction determination method according to claim 4 to calculate a color material mixture ratio. This is a method of calculating a coloring material mixing ratio, which is characterized in that:

According to a sixth aspect of the present invention, there is provided an apparatus for calculating a color gamut reproducible by a combination of color materials, comprising: 1. A mechanism for measuring or preparing the spectral transmittance of a single color material in several steps from the minimum density to the maximum density. Using the measured values as input, a large number of predicted optical densities of various color material density combinations in a certain color material combination were calculated from a relational expression "color material density-optical density" calculated from the Lambert-Beer equation. 2. an arithmetic unit that calculates a predicted spectral transmittance from the optical density using the Lambert-Beer equation and calculates three-dimensional color space coordinates from the calculated multiple spectral transmittances; A color material color gamut calculation device comprising at least a storage device for storing three-dimensional color space coordinates calculated by the arithmetic device.

According to a seventh aspect of the present invention, there is provided an apparatus for calculating a color gamut reproducible by a combination of color materials, comprising: 1. A mechanism for measuring or preparing the spectral reflectance of a single color of a color material in several steps from the minimum density to the maximum density. With the measured values as inputs, a number of predicted scattering absorption coefficients of various color material concentration combinations in a certain color material combination are calculated from a relational expression “color material concentration-scattering absorption coefficient” calculated from the Kubelka-Munk equation. Calculating the calculated spectral reflectance from the scattering coefficient using the Kubelka-Munk equation, and calculating the color gamut expressed in a three-dimensional color space from the calculated multiple spectral reflectances Device, 3. A color material color gamut calculation device comprising at least a storage device for storing three-dimensional color space coordinates calculated by the arithmetic device.

According to an eighth aspect of the present invention, there is provided an apparatus for calculating a color gamut reproducible by a combination of color materials, comprising: 1. A mechanism for measuring or preparing the spectral transmittance and spectral reflectance of a single color of a color material in several stages of color material densities from a minimum density to a maximum density. With the measured values as inputs, a number of predicted scattering absorption coefficients of various color material concentration combinations in a certain color material combination are calculated from a relational expression “color material concentration-scattering absorption coefficient” calculated from the Kubelka-Munk equation. An arithmetic unit for calculating, calculating the spectral reflectance from the scattering coefficient using the Kubelka-Munk equation, and calculating the color gamut expressed in a three-dimensional color space from the calculated multiple spectral reflectances; . A color material color gamut calculation device comprising at least a storage device for storing three-dimensional color space coordinates calculated by the arithmetic device.

Further, a ninth invention of the present invention relates to an apparatus for judging whether color reproduction is possible or not. 1. A mechanism for measuring a spectral transmittance and / or a spectral reflectance of a target color; A storage device for storing the color material gamut obtained by the color material gamut calculation device according to any one of claims 6 to 8. Calculating three-dimensional color space coordinates from the spectral transmittance and / or spectral reflectance of the target color and determining whether the stored color material color gamut includes the three-dimensional color space coordinates of the target color Device, 4. A color reproduction determination device comprising at least an output device that outputs the determination result.

According to a tenth aspect of the present invention, there is provided an apparatus for performing a CCM calculation to obtain a color material mixing ratio. 1. Basic database for CCM calculation, 2. An arithmetic unit that performs computer color matching with a combination of color materials determined to be reproducible by the color reproduction determination device and calculates a color material mixture ratio. A color material mixture ratio calculation device, comprising at least an output device for outputting the color material mixture ratio of the calculation result.

The measured value uses the spectral transmittance, the spectral reflectance, or both of them, because it is necessary to change the measuring method depending on the transparency and opacity of the color material to be measured. It is necessary to measure the spectral transmittance of a coloring material having high transparency, the spectral reflectance of a coloring material having high concealing property, and to measure both if both are not sufficient.

[0019]

Next, the present invention will be described in detail with reference to the drawings. In this description, the CIE1976 (L ^* a ^* b ^* ) color space (hereinafter, CIELA) is used in the three-dimensional color space.
B), but also CIE1976
Expression can also be made in (L ^* u ^* v ^* ) color space (hereinafter abbreviated as CIELV). CIELAB is mainly used for displaying an object color, and CIELV is mainly used for displaying a color of light. CIELAB is also used for displaying light colors, and has become a de facto industry standard in the world of color management. However, the color space in the present invention is for examining which color material can reproduce the target color, and it is not a main purpose to find a numerical value of the color. Therefore, no matter what color space is used, the effect does not change significantly. First,
A color material color gamut calculation method will be described. FIG. 1 is a flowchart showing an example of a procedure for calculating a color material color gamut to be obtained from basic data of spectral transmittance of each color material.

Procedure 1) Preparation of basic color material data: Measure and prepare single-color density-specific transmittance data or density-specific reflectance data of each color material used in the desired color material color gamut. The data for each density is created by measuring several levels of color material density from the minimum density (0%) to the maximum density (100%). When used in combination with the CCM, the basic data of the CCM may be used as it is. By doing so, there is no need for new measurement for obtaining the color gamut, and the color gamut can be calculated only by the subsequent calculations.

Procedure 2) Formulation of relational expression between color material density and OD (K / S): When the color material is measured by spectral transmittance,
According to the Lambert-Beer equation, the optical density (Optical Density or less, OD) obtained from the spectral transmittance of each color material holds the additive property, and the optical density of the mixed color material can be obtained. Therefore, first, the optical density is calculated from the spectral transmittances of several color material densities by using equation (1). _{OD n λ = -ln (T n} λ) ··· (1) where, OD is the optical density, lambda is the wavelength, T is the spectral transmittance, calculate this for n colorant concentration D I do. Although the natural logarithm is used here, a common logarithm may be used. In this case, an exponent with a base of 10 is returned in Expression (5) described later. Next, a relational expression between the color material density and the optical density is created from the obtained data of the color material density and the optical density.
This relational expression may be any one of linear approximation, quadratic or higher-order curve approximation, and linear interpolation, as long as it is in line with the data. If the calculation accuracy of the theoretical formula is not good in CCM, parameter correction may be performed on the relational expression. However, in the case of color gamut calculation, a correction coefficient may be created and corrected based on the same concept. .

When a color material is measured by spectral reflectance or spectral transmittance / spectral reflectance, according to the Kubelka-Munk equation, the spectral reflectance of each color material and the scattering and absorption determined from the spectral reflectance. In the relation (hereinafter referred to as K / S), the additivity is established, and the K / S of the mixed color material can be obtained. At this time, if the colorant has a sufficient concealing property, the additivity is satisfied even if the value is set to zero without measuring the spectral transmittance. Therefore, first, K / S is calculated by the equation (2) from the spectral transmittance and spectral reflectance of some color material densities. _{K / S n λ = (1} + R n λ 2 -T n λ 2) / 2 / R n λ-1 ··· (2) where, K / S is the scattering coefficient, lambda is the wavelength, R represents the spectral reflectance , T is the spectral transmittance, which is calculated by dividing n color material densities D
Calculate against Next, the obtained color material density and K /
Create a relational expression for S. This relational expression may be any one of linear approximation, quadratic or higher-order curve approximation, linear interpolation, and any data that is in line with the data. Also, CC
If the calculation accuracy of the theoretical formula is not good in M, parameter correction may be performed on the relational expression. However, in the case of color gamut calculation, a correction coefficient may be created and corrected based on the same concept.

Procedure 3) Predicted OD of mixed color material (predicted K /
Calculation of S): When the color material is measured by spectral transmittance, as described above, the OD of the mixed color material can be obtained by the sum of the OD of each color material by the Lambert-Beer equation, as described above.
The optical density ODmix of the mixed color material can be obtained by Expression (3). _{ODmixλ = OD A λ + OD E} λ + OD C λ ··· (3) where, lambda is the wavelength, OD _A is the concentration D _A colorant A OD, O
D _B is the concentration D _B of the coloring material B OD, OD _C is the concentration of the coloring material C D _C
OD. The optical density of each color material is determined by using a relational expression between the color material density and the optical density determined in step 2.

When the color material is measured by spectral reflectance or spectral transmittance / spectral reflectance, as described above,
According to the Kubelka-Munk equation, the K / S of the mixed color material can be obtained by the sum of the K / S of each color material, and the scattering coefficient K / Smix of the mixed color material can be obtained by equation (4). _{K / Smixλ = K / S A} λ + K / S B λ + K / S C λ ··· (4) where, K / S _A is K / S concentrations D _A colorant A, K / S _B
Is the K / S of the density D _B of the color material B, and K / S _C is the density D of the color material C.
It is K / S of _C. The scattering coefficient at each color material concentration is determined using the relational expression between the color material concentration and the scattering coefficient determined in step 2. However, as for the mixed color material, only a combination in which the sum of the densities of the respective color materials does not exceed 100% can be created.

Step 4) Calculation of the predicted spectral transmittance (predicted spectral reflectance) of the mixed color material: When the color material is measured by the spectral transmittance, the prediction of the mixed color material is performed using the Lambert-Beer equation. The spectral transmittance Tmix is obtained by Expression (5). Tmixλ = 1 / EXP (ODmixλ) (5) When the target color material is measured by spectral reflectance or spectral transmittance / spectral reflectance, the mixed color is obtained from the Kubelka-Munk equation. The spectral reflectance Rmix of the material is obtained by Expression (6). Rmixλ = 1 + (K / Smixλ) − ((K / Smixλ) ² + 2 × (K / Smixλ)) ^1/2 (6)

Step 5) Prediction L ^* a ^* b ^{* of} mixed color material: Spectral transmittance Tmi of mixed color material thus obtained
A three-dimensional uniform color space, for example, L ^* a ^* b ^* coordinates of CIELAB is obtained from xλ or the spectral reflectance Rmixλ and recorded. (Calculation method of L ^* a ^* b ^* is omitted)

Step 6) Iterative calculation of color mixture L ^* a ^* b ^* coordinates: Returning to step 3, change the values of density D _A , D _B , and D _C of color material and perform calculation again to create a color gamut. The calculation is repeated as many times as necessary to obtain enough data. Combinations of mixed colors are created evenly. For example, each color material is prepared in 10 densities, and the calculation is repeated with a combination excluding a color mixture exceeding 100%.

Step 7) Creation of color material color gamut: prediction L of a large number of mixed color materials obtained by repeating calculations of steps 3 to 5
^* a ^* b ^* is plotted to determine the color gamut. The obtained color material color gamut is recorded as a pair with the used color material combination. However,
The color gamut that can be used at this time is not limited to the CIELAB color space.

Step 8) Repetitive calculation of color material color gamut: Returning to step 1, the basic data of the color material is changed and the calculation is performed again, and the calculation is repeated until the desired color material color gamut is obtained.

Next, a method of calculating the composition will be described. FIG.
FIG. 9 is a flowchart illustrating an embodiment of a color mixture ratio calculation method using the above-described color reproduction determination method after all color gamut of a desired color material is obtained.

Step 11) Measure L ^* a ^* b ^* of target color:
The target color is measured, and L ^* a ^* b ^* is calculated.

Step 12) Color material color gamut selection: One of the color material color gamut obtained by the above method is selected.

Step 13) Intra-color gamut determination of target color: It is determined whether the target color is within the color gamut of the color material combination selected in step 12. Since various methods have already been used for this color gamut inside / outside determination, these methods may be used.
For example, there is a method of determining whether a target value is inside or outside using a color gamut section display pixel.

Step 14) Repeat determination for all color material gamut: Returning to step 12, the determination is repeated for all color material gamut.

Step 15) Color reproducibility determination: It is determined whether there is a color gamut in which the target color can be reproduced. For example, the determination is made using a method for determining whether a target value is inside or outside using a color gamut section display pixel.

Step 16) CCM calculation using color material judged OK: If there is a color material color gamut that can be reproduced in step 15, CCM calculation is performed using the color material. This CCM calculation may be performed by a generally used method.

Step 17) Indication that there is no reproducible color gamut: If there is no reproducible color material color gamut in step 15, it indicates that there is no reproducible color gamut.

Step 18) Display of blending result: C in step 16
The result of the CM calculation is displayed.

Here, in step 14, after the determination is made for all color material color gamuts, C is determined for all color materials capable of color reproduction.
Although the flowchart for performing the CM calculation is shown, when a color material gamut in which the target color is determined to be OK is found, the procedure 1 is executed.
Alternatively, a flowchart may be adopted in which the determination of color gamut 3 inside or outside is stopped.

Next, a color material color gamut calculation device, a color reproduction judgment device, and a color material mixture ratio calculation device of the present invention will be described with reference to FIG. The color material color gamut calculation device stores an arithmetic unit 3 that performs various calculations by using the spectral transmittance / reflectance measurement mechanism 1 or the CCM calculation basic database 2 as an input, and the obtained color gamut of a three-dimensional color space. It comprises a storage device 5. At this time,
The obtained color gamut may be output to an output device 4 such as a display or a printer in a three-dimensional view of a three-dimensional color space.

The color reproduction determining device includes a measuring mechanism 1 for measuring the spectral transmittance and reflectance of the target color, a storage device 5 for storing a color gamut of a selected color material in a three-dimensional color space, An arithmetic unit 3 for comparing and determining the color gamut of the determined color material in the three-dimensional color space with the color gamut of the target color, and an output device 4 for outputting the determined result. The color material mixing ratio calculation device performs a computer color matching using a combination of the basic database for CCM calculation 2 and the color materials determined to be reproducible by the color reproduction determination device, and calculates a color material mixing ratio. 3 and an output device 4 such as a display or a printer for outputting a color material mixture ratio as a calculation result. As described above, since the color material color gamut calculation device, the color reproduction determination device, and the color material mixture ratio calculation device have many common components, the device may include all the components 1 to 5 shown in FIG. .

<Embodiments> The present invention will be described in more detail with reference to specific embodiments of the present invention. In this example, the color gamut of a certain ink combination was calculated based on the spectral transmittance data of the ink measured by the CCM colorimeter in accordance with the flowchart of FIG. The inks used are yellow, magenta and cyan inks of the water-based ink "Aqua Plus" manufactured by Toyo Ink.

First, a part of the basic data of the spectral transmittance obtained by the method of Procedure 1 is shown in Table 1. In addition, L of basic data
^{The *} a ^* b ^* coordinates are displayed in FIG.

[Table 1]

Next, a relational expression between the color material density and the optical density was obtained. The relational expression was created by performing a linear interpolation between the densities of the optical densities OD of the respective color materials in Table 2 calculated using the equation (1) from the spectral transmittances in Table 1 in accordance with the procedure 2.

[Table 2]

Next, the predicted optical density was determined from equation (3) according to procedure 3, and the predicted spectral transmittance was determined from equation (5) according to procedure 4. The calculated value at this time is defined as yellow density 5
%, Magenta density 5%, and cyan density 60% are shown in Table 3 respectively.

[Table 3]

Next, a predicted L ^* a ^* b ^* was determined from the predicted spectral transmittance data. Table 4 shows the prediction L ^* a ^* b ^* of the color mixture described above.

[Table 4] Steps 3 to 5 are repeatedly performed while changing the density of the color material to be mixed, to thereby predict L ^* a ^* b of a large number of mixed color materials.
^* Was calculated, and a predicted color L ^* a ^* b ^* was plotted by the procedure 7 to obtain a color gamut. FIG. 4 shows a three-dimensional view based on the L ^* a ^* b ^* coordinates. FIG. 5 shows an a ^* b ^* coordinate diagram of the conventional method.

In this example, the color gamut of FIG. 4 could be calculated from the basic data of FIG. In order to know this effect, a comparison with a color gamut obtained by a conventional method and a result obtained by a blending calculation based thereon are compared. In comparison of color gamut, as can be seen by comparing FIGS. 4 and 5, there is a color gamut that cannot be expressed in two dimensions, which can be displayed in a three-dimensional color space, and the accuracy has certainly increased. Table 5 shows a comparison of the results of the calculation of the composition with the conventional method. As a result of experiments, there have been cases where it is determined that color reproduction can be performed in a combination that cannot be actually reproduced by calculation using the conventional method, but it is determined that color reproduction can be performed only for colors that can be reproduced by calculation according to the present invention.

[Table 5]

[0048]

As described above, the color material color gamut calculation method of the present invention makes it possible to calculate the color gamut of a color material more accurately than the conventional method. Further, by combining the CCM with the CCM, it is possible to accurately perform the process from the determination of the color material of the target color to the calculation of the blending, and the blending with the wrong coloring material is not performed. In addition, since there are many combinations that select three colors from ten or more types of color materials, it is preferable to determine only some practical combinations that can cover a wide color gamut. On top of that, when the color reproduction determination method of the present invention is used, it becomes easy to divert the remaining color material to another color of the same color material combination, thereby making it possible to reduce the inventory of the color material, Material purchasing costs can be reduced.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating an example of a color material color gamut calculation method according to the present invention.

FIG. 2 is a flowchart illustrating an example of a color mixture ratio calculation method using the color reproduction determination method of the present invention.

FIG. 3 shows L of basic data used for calculating a color material color gamut according to the present invention.
It is a three-plan view by ^* a ^* b ^* coordinates.

FIG. 4 is a three-plan view of L ^* a ^* b ^* coordinates of a color material gamut obtained by the color material color gamut calculation method of the present invention.

FIG. 5 is an a ^* b ^* coordinate diagram of a color material color gamut obtained by a conventional method.

FIG. 6 is a diagram illustrating a color material color gamut calculation device and a color reproduction determination device according to the present invention;
FIG. 2 is a block diagram illustrating a color material mixture ratio calculation device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Spectral transmittance / reflectance measuring device 2 ... Basic database for CCM calculation 3 ... Operation device 4 ... Output device 5 ... Storage device

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Akihiro Tsukada 1-5-1, Taito, Taito-ku, Tokyo Inside Toppan Printing Co., Ltd. (72) Inventor Masaru Masuda 1-1-5-1, Taito, Taito-ku, Tokyo Letterpress F Term (Reference) 2G020 AA08 DA05 DA14 DA23 DA52 DA65 5B057 AA11 CE17 CE18 CH01 CH20 DB06 DB09 DC25 5C077 LL19 MP08 PP33 PP36 PP37 PP39 PQ12 SS04 TT08 5C079 HB03 HB08 HB11 KA15 LA03 NA02

Claims (10)

[Claims] In calculating a color gamut that can be reproduced by a combination of color materials, 1. A step of measuring or preparing the spectral transmittance of the color material in a single color for several levels of the color material density from the minimum density to the maximum density; Using the measured values, a large number of predicted optical densities of various color material density combinations in a certain color material combination are created from the relational expression “color material density-optical density” obtained from the Lambert-Beer equation. Process, 3. 3. calculating the spectral transmittance from the optical density using the Lambert-Beer equation; Calculating a color gamut expressed in a three-dimensional color space from the calculated plurality of spectral transmittances. 2. Calculation of a color gamut that can be reproduced by a combination of color materials: 1. A step of measuring or preparing the spectral reflectance of a color material in a single color for several levels of color material density from a minimum density to a maximum density; From the relational expression “colorant density-scattering absorption coefficient” obtained from the Kubelka-Munk equation using the measured values, a number of predicted scattering absorption coefficients of various combinations of colorant concentrations in a certain coloring material combination are calculated. 2. the process of creating; 3. calculating the spectral reflectance from the scattering coefficient using the Kubelka-Munk equation; Calculating a color gamut expressed in a three-dimensional color space from the calculated plurality of spectral reflectances. 3. In calculating a color gamut that can be reproduced by a combination of color materials, 1. A step of measuring or preparing the spectral transmittance and spectral reflectance of a single color of the color material in several steps from the minimum density to the maximum density. From the relational expression “colorant density-scattering absorption coefficient” obtained from the Kubelka-Munk equation using the measured values, a number of predicted scattering absorption coefficients of various combinations of colorant concentrations in a certain coloring material combination are calculated. 2. the process of creating; 3. calculating the spectral reflectance from the scattering coefficient using the Kubelka-Munk equation; Calculating a color gamut expressed in a three-dimensional color space from the calculated plurality of spectral reflectances. 4. A method for judging whether color reproduction is possible or not: 1. a step of measuring a target color and calculating a value in a three-dimensional color space; At least a step of determining whether a color material gamut obtained by the color material gamut calculation method according to any one of claims 1 to 3 includes a value of a three-dimensional color space of a target color. A color reproduction determination method characterized by the following. 5. A color material composition, wherein computer color matching is performed with a combination of color materials reproducible by the color reproduction determination method according to claim 4, and a color material composition ratio is calculated. Ratio calculation method. 6. An apparatus for calculating a color gamut reproducible by a combination of color materials, comprising: 1. A mechanism for measuring or preparing the spectral transmittance of a single color material in several steps from the minimum density to the maximum density. Using the measured values as input, a large number of predicted optical densities of various color material density combinations in a certain color material combination were calculated from a relational expression "color material density-optical density" calculated from the Lambert-Beer equation. 2. an arithmetic unit that calculates a predicted spectral transmittance from the optical density using the Lambert-Beer equation and calculates three-dimensional color space coordinates from the calculated multiple spectral transmittances; A color material color gamut calculation device, comprising: at least a storage device that stores three-dimensional color space coordinates calculated by the arithmetic device. 7. An apparatus for calculating a color gamut reproducible by a combination of color materials, comprising: 1. A mechanism for measuring or preparing the spectral reflectance of a single color of a color material in several steps from the minimum density to the maximum density. With the measured values as inputs, a number of predicted scattering absorption coefficients of various color material concentration combinations in a certain color material combination are calculated from a relational expression “color material concentration-scattering absorption coefficient” calculated from the Kubelka-Munk equation. Calculating the calculated spectral reflectance from the scattering coefficient using the Kubelka-Munk equation, and calculating the color gamut expressed in a three-dimensional color space from the calculated multiple spectral reflectances Device, 3. A color material color gamut calculation device, comprising: at least a storage device that stores three-dimensional color space coordinates calculated by the arithmetic device. 8. An apparatus for calculating a color gamut reproducible by a combination of color materials, comprising: 1. A mechanism for measuring or preparing the spectral transmittance and spectral reflectance of a single color of a color material in several stages of color material densities from a minimum density to a maximum density. With the measured values as inputs, a number of predicted scattering absorption coefficients of various color material concentration combinations in a certain color material combination are calculated from a relational expression “color material concentration-scattering absorption coefficient” calculated from the Kubelka-Munk equation. An arithmetic unit for calculating, calculating the spectral reflectance from the scattering coefficient using the Kubelka-Munk equation, and calculating the color gamut expressed in a three-dimensional color space from the calculated multiple spectral reflectances; . A color material color gamut calculation device, comprising: at least a storage device that stores three-dimensional color space coordinates calculated by the arithmetic device. 9. An apparatus for judging whether color reproduction is possible or not: 1. A mechanism for measuring a spectral transmittance and / or a spectral reflectance of a target color; A storage device for storing the color material gamut obtained by the color material gamut calculation device according to any one of claims 6 to 8. Calculating three-dimensional color space coordinates from the spectral transmittance and / or spectral reflectance of the target color and determining whether the stored color material color gamut includes the three-dimensional color space coordinates of the target color Device, 4. A color reproduction determination device comprising at least an output device that outputs the determination result. 10. An apparatus for performing a CCM calculation to obtain a color material mixing ratio, comprising: 1. Basic database for CCM calculation, 2. An arithmetic unit that performs computer color matching with a combination of color materials determined to be reproducible by the color reproduction determination device according to claim 9, and calculates a color material mixture ratio. A color material mixture ratio calculation device, comprising: at least an output device that outputs a color material mixture ratio of the calculation result.