JP6926744B2 - Print color adjustment system and print color adjustment method - Google Patents

Description

The present invention relates to a print color adjustment system and a print color adjustment method for adjusting the color of a printed matter output by an inkjet printer or a digital printing machine to the color of a printed matter printed with halftone dots.

In gravure printing, screen printing, offset printing, etc., the reproduction color is adjusted by area modulation (area modulation gradation expression) and density modulation (density modulation gradation expression), and a predetermined image is printed on the print medium. ..
These prints are suitable for mass printing in which a large number of sheets are printed, and are not suitable for printing a small number of sheets due to cost issues.
For this reason, when the number of printed matter is insufficient, it is costly to reprint in the above printing, so it is necessary to print an extra predetermined number of printed matter and store it as inventory.

However, when stored as inventory, the cost for inventory is wasted if the extra printed inventory is no longer used.
In addition, it is necessary to secure a place to store the inventory, and in order to store the inventory of a plurality of types of printed matter, a large storage place must be prepared, and a lot of wasted space is used.

Therefore, when a small amount of reprinting is required, a simple printing device such as an inkjet printer or a digital printing machine is used as an output device for printed matter.
At this time, it is necessary that the colors of the printed matter printed in large quantities and the printed matter of the simple printing device match, and color management for matching is performed. That is, the color profile of a printing machine that performs mass printing (converting the area modulation gradation expression into a predetermined reference color information (for example, CIELAB value)) and the color profile of a simple printing device (the reference color information is converted into a printing device). (Converted to the control value of) and match the colors of the mass-printed printed matter and the printed matter of the simple printing device (see, for example, Patent Document 1 and Patent Document 2).

Special Table 2007-516663A Japanese Unexamined Patent Publication No. 2006-329753

However, if the color of the printed matter deviates from the above color profile or is intentionally changed due to variations in printing on the printing machine, the printed matter of a simple printing device printed using the color profile and the printed matter of the printing machine. The color does not match the printed matter printed in.
In addition, regarding spot colors, it is often the case that a color profile has not been created, and even if there is, it is difficult to match the colors of the printed matter of a simple printing device and the printed matter printed by the printing machine for the reasons described above. Is.

Further, it is conceivable to adjust the color printed by the simple printing device to the color of the printed matter of the printing machine by adjusting the control value (for example, CMYK value) of the printing device.
However, when printing with multiple spot colors, if you try to adjust the color of one of the spot colors, for example, by adjusting the CMYK value, the colors of all the spot colors will change, and only the color of one of the spot colors will change. Cannot be changed, and the overall color deviates from the color of the printed matter.

The present invention has been made in view of such a situation, and the color of the printed matter printed by the area modulation gradation expression or the density modulation gradation in the printing machine matches the color of the printed matter printed by a simple printing device. As described above, the print color adjustment system and the print color adjustment method for adjusting the control value of the printing device corresponding to the adjustment method of the printing machine are provided.

In the print color adjustment system of the present invention, from the color measurement value of each solid printing of the ink used for the printed matter printed by the area modulation gradation or the density modulation gradation, from the command value of the area modulation gradation or the density modulation gradation. Image data of the printed matter is obtained by a color profile generator that generates a color profile of a first printing machine that prints the printed matter by using a print color prediction model that obtains a predicted value of the color of the printed matter to be printed, and the color profile. The predicted value of the color corresponding to the command value of each dot in the above is obtained, the predicted value is used as the color information of the color of the printed matter, and the color information is converted into the control value by the color profile of the second printing machine. 2. The print control unit that outputs to the printing machine and the parameters used for calculating the prediction of the predicted color in the printing color prediction model are adjusted, and the plurality of printings correspond to the parameters adjusted in a plurality of stages. It is provided with an adjustment control unit that generates a color prediction model and generates a plurality of the color profiles, and the print color prediction model predicts the predicted value when the ink is overprinted, and each of the inks is solid. It includes a process of obtaining the spectral reflectance of each dot of the printed matter by the Kubelka-Munk equation using the absorption coefficient and the scattering coefficient of the print, and obtains the color value of the ink for solid printing in the Kubelka-Munk equation. It characterized the Mochiiruko as said parameter.

Print color adjustment system of the present invention, prior Symbol print control unit, the respective control values obtained from each of the color profile, and outputs the second printing press.

The print color adjustment system of the present invention is characterized in that the thickness of the ink for solid printing in the Kubelka-Munk equation is used as the parameter.

The print color adjustment system of the present invention is characterized in that the gradation characteristic of the predicted color in the halftone of the command value is used as the parameter.

The printing color adjustment system of the present invention obtains the spectral reflectance of the ink to be superimposed on another ink when the predicted color when the ink is overprinted is changed. It is characterized in that the thickness of is used as the parameter.

Print color adjustment system of the present invention, the adjustment control unit, when adjusting the misregistration before Kishirushi Surimono, shifting the position of each of the plate of the ink of the printed material, the printing control section, the position It is characterized in that the predicted value of the color of each dot of the printed matter is obtained in the shifted overlap of the plates.

The print color adjustment system of the present invention is characterized in that the adjustment control unit superimposes noise on the predicted value of the image data.

The print color adjustment method of the present invention is based on a color measurement process for measuring the color measurement value of each solid print of the ink used for the printed matter printed by the area modulation gradation or the density modulation gradation, and the area based on the color measurement value. A process of generating a color profile of a first printing machine for printing the printed matter by using a print color prediction model for obtaining a predicted value of the color of the printed matter to be printed from command values of the modulation gradation and the density modulation gradation, and the process described above. The predicted value of the color corresponding to the command value of each dot in the image data of the printed matter is obtained from the color profile, the predicted value is used as the color information of the color of the printed matter, and the color information is used by the color profile of the second printing machine. The process of converting to a control value and outputting to the second printing machine, and the color of the printed matter printed by the first printing machine and the color of the printed matter printed by the second printing machine are compared. Then, the process of selecting the parameters that need to be adjusted in the print color prediction model and the parameters are changed in multiple stages to generate a plurality of the print color prediction models, which correspond to each of the print color prediction models. In the process of generating each of the color profiles, the process of causing the second printing machine to print the image data by each of the control values corresponding to the color information obtained from each of the color profiles, and the printing color prediction model. The process of adjusting the parameters used in the calculation of the prediction of the predicted color, generating the plurality of printing color prediction models corresponding to the parameters adjusted in a plurality of stages, and generating the plurality of the color profiles. seen including, the print color predicting model, the prediction of the predicted value at the time of overprinted with the above ink, using the absorption and scattering coefficients of the solid printing of each ink, the spectral reflectance in each dot of the printed matter the includes a process for obtaining the equation of Kubelka-Munk, and wherein the Mochiiruko the color value of the ink solid printing in the formula of the Kubelka-Munk as said parameter.

As described above, according to the present invention, the printing machine so that the color of the printed matter printed by the area modulation gradation or the density modulation gradation in the printing machine matches the color of the printed matter printed by a simple printing device. It is possible to provide a print color adjustment system and a print color adjustment method for adjusting control values of a printing device, which correspond to ink adjustment by area modulation gradation and density modulation gradation.

It is a block diagram which shows the structural example of the print color adjustment system by 1st Embodiment of this invention. It is a block diagram which shows the structural example of the color prediction model generation part 12 in FIG. It is a figure explaining the correspondence relationship between the command halftone dot area ratio and the appearance rate of the density gradation region in the halftone dot formed by the command halftone dot area ratio. It is a flowchart which determines the compounding ratio of the primary color ink which comprises a spot color ink, _{and calculates the absorption coefficient K t} (λ) and the scattering coefficient _{St (λ) of a spot color ink.} It is a figure explaining the calculation of _{the density gradation spectral reflectance Rim} (λ) of the ink printed overlaid on the ink as a base. It is a flowchart which shows the process of calculating the Neugebauer primary color by superimposing the spot color ink. It is a figure explaining the calculation of the ratio of the occurrence rate of the overlap of the density gradation area of the base ink, and the density gradation area of the ink printed overlaid on the base ink (spot color ink or primary color ink). It is a figure of the table which shows the calculation result of each appearance rate of the area Q1 to the area Q9 in FIG. 7. It is a flowchart explaining the operation example of the color profile generation processing by the color prediction model generation unit 12 and the color profile generation unit 13 in this embodiment. It is a flowchart explaining the operation example of the adjustment process which makes the printing color of a printing device the same as the color of the printed matter of the printing machine by the printing color adjustment system in this embodiment.

In the present invention, a mesh dot printed matter that reproduces the color of an image by printing ink in a mesh dot shape on a printing medium by a method such as gravure printing, screen printing, and offset printing with a printing machine (commercial printing machine). When printing the same image data with the same color on a simple printing machine (printing device) such as an inkjet printer or digital printing machine, inkjet is performed by adjusting the parameters of the color prediction model that models the mesh dot shape. Adjust the color of the printer.
Hereinafter, in the present embodiment, gravure printing will be described.
In gravure printing, when ink is printed on a printing medium, halftone dots corresponding to the command halftone dot area ratio indicating the degree of gradation are formed on the surface of the printing medium. For halftone dots, the area of the surface of the print medium on which the ink is printed (area-modulated gradation expression) and the thickness of the printed ink (density-modulated gradation expression) change according to the command halftone dot area ratio. .. For example, it can be said that the halftone dots formed in printing resemble the structure of a mountain. The larger the mountain, the wider the base and the higher the height, and the smaller the mountain, the narrower the base and the lower the height. .. That is, as for the halftone dots in printing, not only the area where the ink is printed but also the thickness of the ink to be printed changes according to the command halftone dot area ratio.

Therefore, in the present invention, the color of each gradation of a single color or a spot color of each dot in a halftone dot printed matter printed on a print medium (for example, paper) is predicted by the above prediction model, and the prediction is performed. The result (for example, CIELAB value) is converted into color data such as CMYK format by the ICC (International Color Consortium) profile of the printing inkjet printer and output to the inkjet printer. Then, as already described, when adjusting the color in the printing of the inkjet printer, the color of the inkjet printer is adjusted by adjusting the parameters of the color prediction model instead of controlling the control value of the inkjet printer.

Hereinafter, a configuration example of the print color adjustment system in FIG. 1 will be described with reference to the drawings.
FIG. 1 is a block diagram showing a configuration example of a print color adjustment system according to the first embodiment of the present invention.
In FIG. 1, the print color adjustment system 1 includes an input control unit 11, a color prediction model generation unit 12, a color profile generation unit 13, an adjustment control unit 14, a control value generation unit 15, a display unit 16, and a print data output unit 17. Each of the storage units 18 is provided.
The input control unit 11 writes and stores the image data for each plate of the ink used for printing the printed matter supplied from the external device in the storage unit 18.
In addition, the user measures the color measurement value of the solid printing of the ink used for printing the printed matter, and prints the color measurement value and the printing order of each ink by an input means (for example, a keyboard) (not shown). Input to the adjustment system 1. As a result, the input control unit 11 writes and stores the color measurement value of the input solid printing of each ink and the printing order of each ink in the storage unit 18 in correspondence with the printed matter.

The color prediction model generation unit 12 generates a color prediction model showing the correspondence between the command halftone dot area ratio given to the printing machine and the predicted spectral reflectance R (λ) of the printing portion (described in detail later). Here, the command halftone dot area ratio is a numerical value given to a commercial printing machine that performs gravure printing or the like as a control value for printing a reference printed matter which is a halftone dot printed matter. That is, the color prediction model generation unit 12 corresponds to the printing order of each ink, obtains the predicted spectral reflectance R (λ) for each combination of the command halftone dot area ratios of each ink, and obtains the predicted spectral reflectance R (λ). ) Is calculated, and a color prediction model (color prediction table) showing the correspondence between the command halftone dot area ratio and the color measurement value is generated.
The color profile generation unit 13 converts into a known ICC profile format based on the color prediction model (color prediction table), and generates a converted color profile (also referred to as a color prediction profile).

The adjustment control unit 14 adjusts the parameters used in the equation used when obtaining the predicted spectral reflectance R (λ) in the color prediction model in a plurality of stages. Then, the adjustment control unit 14 outputs the adjusted parameters of the plurality of stages to the color prediction model generation unit 12, and causes the color prediction model corresponding to each parameter to be generated. Here, when a plurality of types of parameters are adjusted in multiple stages, a color prediction model for the number of combinations of the plurality of types of parameters at each stage is generated. For example, each of the five parameters, if adjusted to 5 different levels, it is the combination of 5 5 ⁼ 3125, 3125 pieces of color prediction model is generated. Further, as a result, the color profile generation unit 13 generates 3125 color profiles based on the 3125 color prediction models.

The control value generation unit 15 uses the color profile generated by the color profile generation unit 13 to obtain a color measurement value for predicting the color to be printed by the command halftone dot area ratio for each of the inks for each pixel of the image data. .. Then, the control value generation unit 15 extracts and obtains a control value corresponding to the predicted color measurement value from the device color profile of the printing device that is trying to print a small amount.

The display unit 16 is, for example, a liquid crystal display or the like, and displays an input screen for data required for processing, an operation screen for performing an operation for processing for generating a control value for the printing device, and the like.
The print data output unit 17 outputs the control value for each pixel of the image data as the image data control value to the printing device to execute printing of the image.

<Color profile generation process for printing press>
The color prediction model described below describes the structure of halftone dots in printing, the area of the surface of the printing medium of the halftone dots on which the ink is printed, and the ink in the halftone dots to be printed, corresponding to the command halftone dot area ratio. A calculation model representing the thickness (core fringe model described later) is used. That is, when performing color prediction for each gradation of a single color or a spot color printed on a print medium (for example, paper), the halftone dots of each gradation generated by the command halftone dot area ratio are a plurality of density gradation regions. A calculation model that models the halftone dot shape generated from (similar configuration to contour lines) is used.

Hereinafter, the color prediction model generation unit 12 in FIG. 1 will be described with reference to the drawings.
FIG. 2 is a block diagram showing a configuration example of the color prediction model generation unit 12 in FIG. In FIG. 2, the color prediction model generation unit 12 includes an input unit 101, a density gradation spectral reflectance calculation unit 102, a density gradation appearance rate calculation unit 103, a density gradation appearance rate table database 104, and a measurement spectral reflectance database. 105, Absorption coefficient / scattering coefficient database 106, Absorption coefficient / scattering coefficient calculation unit 107, Spectral reflectance prediction unit 108, Spectral optical density prediction unit 111, Mixing prediction unit 114, Special color ink Spectral reflectance calculation unit 121, Special color ink combination Ratio determination unit 122, special color ink density gradation appearance rate calculation unit 123, temporary storage unit 125, prediction parameter database 126, approximate color database 128, special color ink reproduction color calculation unit 129, density gradation spectroscopic optical density calculation unit 202, density It includes a gradation appearance rate calculation unit 203 and a density gradation appearance rate table database 204.

The input unit 101 is connected to, for example, an external computer via an input control unit 11, and inputs data such as a command value of a command halftone dot area ratio of each primary color of a primary color ink or a spot color ink set by a user. ..
Further, the input unit 101 outputs data such as a command value of the command halftone dot area ratio of each primary color of the ink set by the user, which is input via the input control unit 11, to each part inside the color prediction model generation unit 12. It may be configured to be used.

In the absorption coefficient / scattering coefficient database 106, the command halftone dot area ratio is 100% for each primary color ink, that is, the coloring of the ink obtained from the printed portion printed on a solid print medium (for example, coated paper). The scattering coefficient S (λ) and the absorption coefficient K (λ) of the layer are written and stored in advance by the external computer or the like. Here, when the scattering coefficient S (λ) and the absorption coefficient K (λ) are obtained, the primary color inks are solidly printed on each of the white and black printing media to create the printed portion.
Then, the spectral reflectance of the colored layer of the ink solidly printed on the surface of each of the white and black printing media is measured. Here, the spectral reflectance of the printed portion on the surface of the print medium on a white background is defined as the measured spectral reflectance on a white background, and the spectral reflectance of the printed portion on the surface of the print medium on a black background is defined as the measured spectral reflectance on a black background.
From the obtained white background measurement spectral reflectance and black background measurement spectral reflectance, the scattering coefficient S (λ) and the absorption coefficient K (λ) in the printed portion in which the primary color ink is solidly printed on the printing medium are obtained. Further, the scattering coefficient S (λ) and the absorption coefficient K (λ) are obtained at a plurality of wavelengths λ in a predetermined wavelength range.

In the approximate color database 128, the color measurement values of the spot color inks and the blending ratios of the primary colors are stored in advance for a plurality of types of spot color inks (reference spot color inks) having different combinations of the blended primary color inks. ..

In the measured spectral reflectance database 105, the measured spectral reflectance Rs (λ) of the printed portion printed on the print medium at a plurality of command halftone dot area ratios for each primary color ink is written in advance by the external computer or the like and stored. Has been done. For example, this printed portion is a step chart printed with the command halftone dot area ratio in m steps. When determining the measured spectral reflectance Rs (λ), halftone dots having a plurality of commanded halftone dot area ratios are printed on a printing medium used for actual printing, respectively, using primary color ink. Here, s is the command halftone dot area ratio. Then, the spectral reflectance of the printed portion printed on the print medium is measured for each printed portion having halftone dots of the command halftone dot area ratio. Further, in the measurement spectral reflectance database 105, the background spectral reflectance R ₀ (λ) of the printing medium used for actual printing is the same as the above-mentioned measured spectral reflectance Rs (λ), such as the external computer or the like. It is written and stored in advance by.

The temporary storage unit 125 is a storage unit that stores the intermediate calculation results of each unit in the present embodiment, and internally includes a scattering absorption coefficient table, a spot color ink blending ratio table, a spot color ink density gradation appearance rate table, and a Neugebauer primary color table. A spectral reflectance table or the like is written and stored.
In the prediction parameter database 126, the weighting coefficient w, which will be described later, used by the mixing prediction unit 114 in the present embodiment is stored. The weighting coefficient w is set so that the error between the spectral reflectance obtained from the model created by printing the training data and the spectral reflectance as the printed teacher data is minimized. It has been demanded. Further, when the Jür-Neilsen modified Neugebauer model is used as the spectral reflectance prediction model of the print color, the n value may be set.

Calculation of Density Gradation Appearance Rate by Spectral Reflectance The density gradation spectral reflectance calculation unit 102 uses the absorption coefficient / scattering coefficient database 106 to indicate the corresponding primary colors according to the type of primary color ink supplied from the input unit 101. The absorption coefficient K (λ) and the scattering coefficient S (λ) of the ink are read out. Further, the density gradation spectral reflectance calculation unit 102 measures spectroscopy for each command net point area ratio from the measurement spectral reflectance database 105 according to the type of primary color ink supplied from the input unit 101 and the type of printing medium. Each of the reflectance Rs (λ) and the background spectral reflectance R ₀ (λ) of the print medium is read out.

Then, the density gradation spectral reflectance calculation unit 102 includes the absorption coefficient K (λ) and the scattering coefficient S (λ) of the primary color ink read from the absorption coefficient / scattering coefficient database 106 measurement spectral reflectance database 105, and the print medium. underlying spectral reflectance R _{0 (lambda)} and _(as will be described later, the thickness factor X _m to change for each density gradation region) thickness coefficients X _m of gray scale of each of the, the following (1) into equation (equation Kubelka-Munk), gray scale spectral reflectance _{R i1 (λ), R i2} (λ), R i3 (λ), ..., and calculates each of _{R im} (lambda).
In the following equation (1), a (λ) is a numerical value obtained by adding the scattering coefficient S (λ) and the absorption coefficient K (λ) and dividing the addition result by the scattering coefficient S (λ). b (λ) is a numerical value obtained by subtracting 1 from the squared value of a (λ) and calculating the square root of the subtraction result.

In this embodiment, expression of the Kubelka-Munk shown in above-mentioned (1) (Kubelka-Munk), namely (1) the thickness of coefficients X _m of printed ink in the equation, the print medium primary ink in solid Based on the printed printed portion, it is used as a numerical value indicating the density gradation of the printed portion. That is, the film thickness coefficient X _m is arbitrarily set. For example, the film thickness is 100% for the solid printed portion having the thickest ink film thickness, the film thickness coefficient is 1, and this 1 is the density gradation. Divide into m according to the number of steps of the film thickness of the region m. For example, if there are five stages of film thickness in the density gradation region indicated by the command halftone dot area ratio, m = 1, 2, 3, 4, 5, and the film thickness coefficient X _m is each density scale. _{X 1} = 1.0, X ₂ = 0.8, X ₃ = 0.6, X ₄ = 0.4, and X ₅ = 0.2, corresponding to the stage of the film thickness in the adjustment region.

As already described, the film thickness coefficient X _{m is calculated by the Kubelka-Munk equation together with the background spectral reflectance R 0} (λ), the absorption coefficient K (λ), and the scattering coefficient S (λ) of the background printing medium. Substituting into a certain equation (1), the spectral reflectance of the density gradation region included in the network points of each command network point area ratio is the density gradation spectral reflectance R _i1 (λ), R _i2 (λ), R. _{Each of i3} (λ), ..., and _Rim (λ) is calculated. The density gradation spectral reflectances R _i1 (λ), R _i2 (λ), R _i3 (λ), ..., R _im (λ) are used in the calculation model described later, and are used in a plurality of halftone dots. It is used as the spectral reflectance of each of the tuning regions.

The density gradation appearance rate calculation unit 103, from the density gradation spectral reflectance calculation unit 102, indicates that the density gradation spectral reflectance R _i1 (λ), R _i2 (λ), R _i3 (λ), ..., R _im ( Read each of λ). Further, the density gradation appearance rate calculation unit 103 reads each of the measured spectral reflectances Rs (λ) for each command halftone dot area ratio from the measured spectral reflectance database 105.
Then, the density gradation appearance rate calculation unit 103 _{applies the} density gradation spectral reflectances R i1 (λ), R _i2 (λ), R _i3 (λ), to the following equation (2) (calculation model). ..., _{Each of Rim} (λ) is substituted, and the calculated spectral reflectance R'(s, λ) is calculated by the process described later.

Here, the density gradation appearance rate calculation unit 103 uses the following equation (3) as a numerical value of the appearance rate (ratio of the area of the density gradation region of each density gradation constituting the halftone dots in the printed portion of the paper). The calculated spectral reflectance R'(s, λ) is calculated while changing. Then, the density gradation appearance rate calculation unit 103 sets the mean square error RMSE of each of the calculated calculated spectral reflectances R'(s, λ) and the measured spectral reflectance Rs (λ) as the command network point area. It is obtained in a predetermined wavelength range for each rate.
The density gradation appearance rate calculation unit 103 obtains the appearance rate of each of the density gradation regions where the mean square error between the calculated spectral reflectance R'(s, λ) and the measured spectral reflectance Rs (λ) is the smallest. .. Here, s is the command halftone dot area ratio.

Then, the density gradation appearance rate calculation unit 103 determines the appearance rate functions a ₁ (s), a ₂ (s), a ₃ (s) of each density gradation region according to the appearance rate of each density gradation region. _..., seek _a m (s). Here, the density gradation appearance rate calculation unit 103 uses the obtained appearance rate for each density gradation region, and fits this appearance rate to a quadratic function of the command halftone dot area ratio s, and the appearance rate. Functions a ₁ (s), a ₂ (s), a ₃ (s), ..., _Am (s) may be obtained. The density gradation appearance rate calculation unit 103 sets the appearance rate functions a ₁ (s), a ₂ (s), a ₃ (s), ..., _Am (s) of each density gradation region obtained as a density scale. The key appearance rate table database 104 is written and stored.

In the above equation (3), the density gradation appearance rate calculation unit 103 sets the mean square error RMSE, which is the sum of the squares of the errors at each wavelength λ, by the step size obtained by dividing the wavelength λ from 380 nm to 730 nm by n. It is calculated for each area ratio.
As described above, the density gradation appearance rate calculation unit 103 uses the calculation model of Eq. (2) to print each density gradation included in the halftone dots in the printed portion where the ink according to the command halftone dot area ratio is printed. , The density gradation spectral reflectance _Rim (λ) of the density gradation and the appearance rate function of the density gradation a ₁ (s), a ₂ (s), a ₃ (s), ..., _Am (s) The result of multiplying by is added to calculate the partial spectral reflectance R'(s, λ) (calculated spectral reflectance) of the printed portion of the command halftone dot area ratio.

FIG. 3 is a diagram for explaining the correspondence between the command halftone dot area ratio and the appearance rate of the density gradation region in the halftone dots formed by the command halftone dot area ratio. In FIG. 3A, the horizontal axis represents the command halftone dot area ratio s, and the vertical axis represents the appearance rate a. With the advent rate function a _{m (s),} it can be determined occurrence of each gray scale region in command area coverage. Density gradation appearance ratio calculating unit 103, already each occurrence rate function a _m for each gray scale region _(s) as described, the concentration floor corresponding to (3) command halftone dot area ratio obtained by the formula It is obtained by converting the appearance rate for each key area into a function as an approximate expression of a quadratic function. _{FIG. 3 (a) shows the appearance rate functions a 1} (s), a ₂ (s), and a ₃ (s) of each of the density gradation regions of the density gradations of 4 gradations when m = 4, that is, , A ₄ (s) are shown.

Further, FIG. 3B is a diagram showing the shapes of halftone dots in each of the _{command halftone dot area ratios s 1} , s ₂ , s ₃ , and s _{4 in FIG. 3 (a) in a plan view.} In the command halftone dot area ratio s ₁ , only the density gradation region P ₁ is formed. Further, in the command halftone dot area ratio s ₂ , the density gradation region P ₂ is formed inside the density gradation region P _1. In the command area coverage s _3, only the density gradation region P ₂ is formed. In the command area coverage s _4, density gradation region P ₄ in the interior of the density gradation region P ₃ is formed. As described above, in the present embodiment, the halftone dot structure in gravure printing is modeled as the halftone dot structure shown in FIG. 2 (b) by using the calculation model of the equation (2).

Returning to Figure 2, density gradation appearance ratio calculating unit 103, the occurrence rate representing the occurrence of each gray scale region in command area coverage of gray scale region determined function a _{m (s),} concentration Floor The key appearance rate table database 104 is written and stored in correspondence with the density gradation spectral reflectance in the density gradation region. Similarly, density gradation appearance ratio calculating unit 103, with respect to each of the other primary color inks, the appearance rate function representing the occurrence of each gray scale region in command area coverage of gray scale region a _m (S) is written and stored in the density gradation appearance rate table database 104.

The spot color ink spectral reflectance calculation unit 121 reads out the spot color ink whose color measurement value is closest to the color measurement value of the solid printing of the ink used for the printed matter from the spot color inks having different combinations of the primary color inks in the approximate color database 128. The approximate color database 128 stores the color measurement values of the special color inks and the combination ratios of the primary colors, and the combination ratios of the read primary colors of the special color inks are used to reproduce the color measurement values of solid printing. Set as a ratio.
Further, the special color ink spectral reflectance calculation unit 121 _{reads the background spectral reflectance R 0} (λ) of the print medium from the measurement spectral reflectance database 105.
The absorption coefficient / scattering coefficient calculation unit 107 increases the absorption coefficient K of each of the primary color inks, for example, the primary color inks # 1 and the primary color inks # 2, which constitute the primary color inks included in the set blending ratio, from the absorption coefficient / scattering coefficient database 106. _{Each of 1} (λ) and K ₂ (λ) and the scattering coefficients S ₁ (λ) and S ₂ (λ) is read out.

_{Then, the absorption coefficient / scattering coefficient calculation unit 107 calculates the absorption coefficient K t} (λ) and the scattering coefficient _St (λ) of the special color ink mixed with the primary color inks by the following equation (4). _{In the case of this spot color ink, the scattering coefficient St} (λ) and the absorption coefficient K _t (λ) of the spot color ink are calculated by the following equation (4) according to the ratio of the primary color inks to be mixed. Further, the special color ink spectral reflectance calculation unit 121 _{writes and stores each of the obtained scattering coefficient St} (λ) and absorption coefficient K _t (λ) of the special color ink in the scattering absorption coefficient table of the temporary storage unit 125. ..

In the above equation (4), each of the coefficient α and the coefficient β is a coefficient indicating the mixing ratio of the primary color ink # 1 and the primary color ink # 2. _{The absorption coefficient K 1} (λ) of the primary color ink # 1 is multiplied by the coefficient α, the absorption coefficient K ₂ of the primary color ink # 2 is multiplied by the coefficient β, and the added value is the absorption coefficient K of the special color ink. _{It is set to t} (λ). _{Similarly, the scattering coefficient S 1} (λ) of the primary color ink # 1 is multiplied by the coefficient α, the scattering coefficient S ₂ (λ) of the primary color ink # 2 is multiplied by the coefficient β, and the added value is calculated. The scattering coefficient _St (λ) of the special color ink is used.

As a result, the special color ink spectral reflectance calculation unit 121 has the absorption coefficient K _t (λ) and the scattering coefficient _St (λ) and the background spectral reflectance R ₀ (λ) of the print medium with respect to the equation (1). And the film thickness coefficient X _{m of the density gradation are substituted to obtain the spectral reflectance RKM} (λ) of the special color ink.
The spot color ink reproduction color calculation unit 129 sets the spectral distribution of the light source in the observation environment and the standard observer with respect to _{the spectral reflectance RKM} (λ) of the spot color ink calculated by the spot color ink spectral reflectance calculation unit 121. It is converted into a color measurement value (for example, L * a * b * value) and output to the spot color ink blending ratio determination unit 122.

The spot color ink blending ratio determination unit 122 confirms the color difference between the color measurement value obtained by the spot color ink reproduction color calculation unit 129 and the color measurement value of solid printing. Then, when the color difference is within a preset allowable range, the spot color ink blending ratio determining unit 122 sets the blending ratio of each of the primary color inks in the color obtained by the spot color ink spectral reflectance calculation unit 121 as a sample spot color ink. The types of the primary color inks constituting the above and the blending ratio thereof are written and stored in the spot color ink blending ratio table of the temporary storage unit 125 together with the spot color ink identification information which is the spot color ink identification information.

FIG. 4 is a flowchart for determining the blending ratio of the primary color inks constituting the spot color ink _{and calculating the absorption coefficient K t} (λ) and the scattering coefficient _St (λ) of the spot color ink.
Step S101:
The user measures the color measurement value of the solid printing used for reproduction and inputs it to the color prediction model generation unit 12.

Step S102:
_{The special color ink spectral reflectance calculation unit 121 reads the background spectral reflectance R 0} (λ), which is the spectral reflectance of the print medium, from the measurement spectral reflectance database 105.

Step S103:
Next, the spot color ink spectral reflectance calculation unit 121 reads out the combination of the primary color inks constituting the spot color ink from the approximate color database 128. For example, at this time, the spot color ink spectral reflectance calculation unit 121 extracts and selects the spot color ink having the color measurement value closest to the color measurement value obtained from the solid printing from the approximate color database 128.

Step S104:
The absorption coefficient / scattering coefficient calculation unit 107 reads out the scattering coefficient S (λ) and the absorption coefficient K (λ) of the primary color inks constituting the special color ink selected in step S103 from the absorption coefficient / scattering coefficient database 106.

Step S105:
The spot color ink blending ratio determination unit 122 sets an initial value for the blending ratio of each of the primary color inks constituting the spot color ink. As the initial value, the blending ratio of the spot colors extracted from the approximate color database 128 in step S103 is set.

Step S106:
Next, as shown in Eq. (4), the absorption coefficient / scattering coefficient calculation unit 107 multiplies each of the primary color inks by the scattering coefficient S (λ) and the absorption coefficient K (λ) of the primary color inks, respectively. ..
_{Then, the absorption coefficient / scattering coefficient calculation unit 107 adds the multiplication results to obtain the scattering coefficient St} (λ) and the absorption coefficient K of the special color ink in the blending ratio (for example, α and β in the equation (4)). _{Calculate t} (λ).

The special color ink spectral reflectance calculation unit 121 _{substitutes the background spectral reflectance R 0} (λ) of _{the printing medium, the scattering coefficient St} (λ), and the absorption coefficient K _t (λ) into equation (1). Then, the spectral reflectance of the special color ink is calculated. Further, the spot color ink reproduction color calculation unit 129 calculates a color measurement value from the spectral reflectance of the spot color ink calculated by the spot color ink spectral reflectance calculation unit 121.
The spot color ink blending ratio determination unit 122 obtains a color difference between the color measurement value L * a * b * value for solid printing and the color measurement value L * a * b * value obtained by the spot color ink reproduction color calculation unit 129.

Step S107:
Then, the spot color ink blending ratio determination unit 122 determines whether or not the color difference is within the preset allowable range.
At this time, if the color difference is within the preset allowable range, the spot color ink blending ratio determination unit 122 proceeds to step S108. On the other hand, if the color difference is not within the preset allowable range, the spot color ink blending ratio determining unit 122 proceeds to step S110.

Step S108:
Next, the spot color ink blending ratio determination unit 122 sets the blending ratio of the primary color inks in the spot color ink corresponding to solid printing as the current blending ratio.
Then, the spot color ink blending ratio determining unit 122 writes and stores the type of the primary color ink in the spot color ink and the blending ratio of each of the primary color inks in the blending ratio table of the temporary storage unit 125.

Step S109:
Next, the spot color ink blending ratio determination unit 122 sets the scattering coefficient _St (λ) and the absorption coefficient K _t (λ) of the spot color ink corresponding to solid printing to the current scattering coefficient _St (λ) and the absorption coefficient K. _{Let t} (λ).
Then, the spot color ink blending ratio determining unit 122 _{writes and stores the scattering coefficient St} (λ) and the absorption coefficient K _t (λ) of the spot color ink in the scattering absorption coefficient table of the temporary storage unit 125.

Step S110:
The spot color ink blending ratio determining unit 122 determines whether or not the number of times the blending ratio is changed is within a preset specification.
At this time, the spot color ink blending ratio determining unit 122 advances the process to step S111 when the number of times the blending ratio is changed is within a preset predetermined number of times. On the other hand, when the number of times the special color ink blending ratio is changed exceeds the preset number of times, the spot color ink blending ratio determining unit 122 proceeds to the process in step S112.

Step S111:
The spot color ink blending ratio determination unit 122 changes the blending ratio of each of the primary color inks constituting the spot color ink.
Then, the spot color ink blending ratio determining unit 122 increments the counter that counts the number of changes in the blending ratio (increments the count value by one), and proceeds to the process in step S106.

Step S112:
The spot color ink blending ratio determination unit 122 displays a selection screen for whether or not to change the combination of primary color inks on a display unit (not shown) of the color prediction model generation unit 12.
When the user selects to change the combination of the primary color inks, the spot color ink blending ratio determination unit 122 advances the process to step S113. On the other hand, when the user selects not to change the combination of the primary color inks, the spot color ink blending ratio determination unit 122 advances the process to step S108.

Step S113:
The spot color ink blending ratio determination unit 122 resets the counter that counts the number of changes in the blending ratio, and sets the count value, that is, the number of changes to "0".

Step S114:
The spot color ink blending ratio determination unit 122 outputs a control signal for changing the combination of the primary color inks to the spot color ink spectral reflectance calculation unit 121.
The spot color ink spectral reflectance calculation unit 121 newly reads out the combination of the primary color inks constituting the spot color ink from the approximate color database 128.

Returning to Figure 2, featuring ink density gradation appearance ratio calculating unit 123 obtains the occurrence rate function a _m for each gray scale region features ink produced by mixing the primary color ink at a predetermined ratio _(s). The features of ink density gradation appearance ratio calculating unit 123, stores write against occurrence rate function a _{m (s)} is in the temporary storage unit 125 features the ink density gradation incidence table obtained. Here, spot ink density gradation appearance ratio calculating unit 123, either the incidence function a _m primary ink constituting the spot color ink _(s), read from the gray scale appearance rate table database 104, the feature ink the occurrence rate function _a m (s). Further, features of ink density gradation appearance ratio calculating section 123, the incidence of each of the primary color inks constituting the spot color inks function a _{m (s),} in combination with the compounding ratio of each primary color inks, the incidence of spot inks it may be as a function _a m (s).

Operation of Spectral Reflectance Prediction Unit 108 Next, the spectral reflectance prediction unit 108 includes an extended Neugebauer primary color calculation unit 1081, an extended Neugebauer primary color appearance rate calculation unit 1082, and a spectral reflectance calculation unit 1083.
The extended Neugebauer primary color calculation unit 1081 determines the ink to be the base (primary color ink or the special color ink) and the ink to be printed on the surface of the base according to the order of the colors to be superimposed. Further, the extended Neugebauer primary color calculation unit 1081 reads the command halftone dot area ratio of each of the inks to be overlapped from the input unit 101.

The extended Neugebauer primary color calculation unit 1081 reads the scattering coefficient S (λ) and the absorption coefficient K (λ) of the primary color ink that overlaps with the underlying ink from the absorption coefficient / scattering coefficient database 106. Further, the extended Neugebauer primary color calculation unit 1081 _{reads the scattering coefficient St} (λ) and the absorption coefficient K _t (λ) of the spot color ink that overlaps with the underlying ink from the scattering absorption coefficient table of the temporary storage unit 125.

_{Next, the extended Neugebauer primary color calculation unit 1081 calculates the density gradation spectral reflectance Rim} (λ) of the density gradation region at the halftone dots of the base ink (spot color ink or primary color ink) according to the formula (1). Substitute as the reflectance R ₀ (λ), and substitute each of the scattering coefficient S (λ) and absorption coefficient K (λ) of the ink that overlaps the underlying ink and the film thickness coefficient X _{m in the density gradation region. By doing so, the density gradation spectral reflectance Rim} (λ) in the density gradation region constituting the halftone dots of the ink printed on the underlying ink is calculated.

Here, the extended Neugebauer primary color calculation unit 1081 has each of the density gradation region of the halftone dots of the background ink and the density gradation region constituting the halftone dots of the ink printed on the background ink. The calculation of the density gradation spectral reflectance _Rim (λ) of the overlapping portion is performed on the density gradation area at the halftone dots of the underlying ink and the ink (special color ink or primary color ink) printed on the halftone dots of the underlying ink. This is performed in all combinations with the halftone dot density gradation region.

FIG. 5 is a diagram illustrating the calculation of _{the density gradation spectral reflectance Rim} (λ) of the ink printed on the ink as the base.
The density gradation spectral reflectance calculation unit 102 sets the spectral reflectance of the print medium as the underlying spectral reflectance R ₀ (λ), and sets the absorption coefficient K (λ) and the scattering coefficient S (λ) in the region of the ink 1000. _{To obtain the density gradation spectral reflectance Rim} (λ) of the density gradation region of the halftone dots in the region of the ink 1000 (special color ink or primary color ink) printed on the printing medium from the equation (1). ..

_{Then, the extended Neugebauer primary color calculation unit 1081 calculates the spectral reflectance R KM} (λ) shown in the region 1005 printed on the upper part of the ink region 1004 with respect to the spectral reflectance ink 1000 shown in the region 1002. .. _{Here, the extended Neugebauer primary color calculation unit 1081 sets the spectral reflectance R KM} (λ) of the density gradation region of the halftone dots in the region of the ink 1000 as the underlying spectral reflectance R ₀ (λ), and is shown in the region 1003. Substituting the absorption coefficient K (λ) and the scattering coefficient S (λ) of the ink 1001 and the film thickness coefficient X _m of the density gradation region into the equation (1), printing is superimposed on the region of the ink 1000 in the region 1004. _{The spectral reflectance R KM} (λ) of the density gradation region at the halftone dots of the region 1004 of the ink 1001 (spot color ink or primary color ink) is obtained.

As a result, the extended Neugebauer primary color calculation unit 1081 has a density gradation region at the halftone dots of the underlying ink (special color ink or the primary color ink) and a density gradation of the halftone dots of the ink printed on the halftone dots of the underlying ink. _{In combination with the area, the spectral reflectance R KM} (λ) in the overlapping area of the halftone dot density gradation area of the upper ink (special color ink or primary color ink) printed on the halftone dots of the underlying ink is determined. As will be described later, by calculating all the combinations of the halftone dots of the underlying ink and the density gradation region at the upper ink halftone dots, the spectral reflectance _{RKM in the printed portion where the inks are overprinted is calculated.} Find (λ). The extended Neugebauer primary color calculation unit 1081 _{writes the obtained spectral reflectance RKM} (λ) in the Neugebauer primary color table of the temporary storage unit 125 and stores it.

FIG. 6 is a flowchart showing a process of calculating the Neugebauer primary color by superimposing the spot color inks. Further, as the ink to be superimposed, not only the special color ink but also the primary color ink and the special color ink may be combined.
Step S201:
The user corresponds to the combination of the special color inks, inputs the printing order of the special color inks in each combination, and sets the color prediction system.

Step S202:
_{The extended Neugebauer primary color calculation unit 1081 reads the background spectral reflectance R 0} (λ), which is the spectral reflectance of the print medium, from the measured spectral reflectance database 105.

Step S203:
The extended Neugebauer primary color calculation unit 1081 reads each of the scattering coefficient S (λ) and the absorption coefficient K (λ) of the spot color inks to be superimposed from the scattering absorption coefficient table of the temporary storage unit 125.

Step S204:
The extended Neugebauer primary color calculation unit 1081 stores the film thickness coefficient, which is a film thickness correction value input by the user, in the spectral reflectance, that is, stores the film thickness coefficient used in the equation (1) in the internal storage unit.

Step S205:
_{The extended Neugebauer primary color calculation unit 1081 calculates the spectral reflectance RKM} (λ) of a printed matter printed using a spot color ink or a primary color ink as a base. At this time, the extended Neugebauer primary color calculation unit 1081 calculates all Neugebauer primary colors of each combination of film thickness coefficients in the spot color inks to be superimposed. That is, the extended Neugebauer primary color calculation unit 1081 obtains the spectral reflectance R _KM (λ) of _{the special color ink printed on the printing medium of the base, and uses the obtained spectral reflectance R KM} (λ) as the spectral reflectance of the new base. And. Then, the extended Neugebauer primary color calculation unit 1081 calculates _{the spectral reflectance when a new special color ink is superposed on the obtained special color ink having the spectral reflectance R KM} (λ), and calculates the spectral reflectance of this when the new special color ink is superimposed. Let the reflectance be R _KM (λ).
Here, when the actual measurement value of the spectral reflectance is known in advance, such as when the base is solid with process ink, the spectral reflectance which is the actual measurement value is superimposed instead of calculating the spectral reflectance when printed on the medium. It may be used as the spectral reflectance of the base material to be combined.
Then, the extended Neugebauer primary color calculation unit 1081 _{writes the calculated spectral reflectance RKM} (λ) in the Neugebauer primary color table of the temporary storage unit 125 and stores it.

Step S206:
The extended Neugebauer primary color calculation unit 1081 determines whether or not the calculation of all Neugebauer primary colors of the combination of the spot color inks has been completed.
At this time, the extended Neugebauer primary color calculation unit 1081 ends the process when all the Neugebauer primary colors have been calculated. On the other hand, the extended Neugebauer primary color calculation unit 1081 proceeds to step S207 when the calculation of all the Neugebauer primary colors is not completed.

Step S207:
The extended Neugebauer primary color calculation unit 1081 changes the combination of the special color inks, sets the order of the special color inks to be overlapped to the order of the next combination of the special color inks, and proceeds to the process in step S205.

Returning to FIG. 2, the extended Neugebauer primary color appearance rate calculation unit 1082 uses the density gradation appearance rate table database 104 to display the appearance rate functions a ₁ (s), a ₂ (s), a ₃ (s), ..., _Am. Read (s).
Then, the extended Neugebauer primary color appearance rate calculation unit 1082 appears at the density region that appears at the halftone dots in the command halftone dot area ratio of the underlying ink and at the halftone dots at the command halftone dot area ratio of the ink that overlaps the underlying ink. each of the probability of occurrence of the density improvement region, appearing read from density gradation occurrence rate table database 104 probability function _{a 1 (s), a 2} (s), a 3 (s), ..., a m (s ).
Further, the extended Neugebauer primary color appearance rate calculation unit 1082 calculates the ratio of the appearance rate of the overlap between the density gradation region of the base ink and the density gradation region of the ink printed on the base ink.

FIG. 7 is a diagram illustrating the calculation of the ratio of the appearance rate of the overlap between the density gradation region of the base ink and the density gradation region of the ink printed on the base ink (spot color ink or primary color ink). Is.
In FIG. 7, for the sake of simplicity, two types of inks to be superimposed are used, and two types of density gradation regions are also used. However, even if there are a plurality of inks to be superimposed and types of density gradation regions of 3 or more, the density gradation region of the underlying ink and the density gradation region of the ink printed on the background ink overlap. The ratio of the appearance rate of the above can be calculated in the same manner as in the following description.

FIG. 7A shows a case where there are two types of density gradation regions, the command halftone dot area ratio (set net%) of ink # 1 and the density scale appearing at the halftone dots in the command halftone dot area ratio. The correspondence with the appearance rate of each of the core and fringe, which are the key regions, is shown. Ink # 2 also has the same correspondence as ink # 1. Each of ink # 1 and ink # 2 is either a primary color ink or a spot color ink. Further, in each of the ink # 1 and the ink # 2, there are two types of density gradation core regions 1 and density gradation fringe regions 2, respectively, and the density gradation core region 1 has a film thickness of 100%. Yes, the density gradation fringe region 2 has a film thickness of 50%. In addition, other inks have a similar correspondence.

FIG. 7B shows the overlap of the density gradation core region 1 and the density gradation fringe region 2. In FIG. 7B, for example, ink # 1 is cyan (C) and ink # 2 is magenta (M). There are nine types of overlapping combinations of the density gradation core region 1 and the density gradation fringe region 2 from region Q1 to region Q9. The region Q1 is a region of only the cyan density gradation core region 1. The region Q2 is a region of only the cyan density gradation fringe region 2. Region Q3 is a region of only the density gradation core region 1 of the magenda. Region Q4 is a region of only the density gradation fringe region 2 of the magenda. The region Q5 is a region where the density gradation core regions 1 of each of cyan and magenta overlap. The region Q6 is a region where the magenta density gradation fringe region 2 and the cyan density gradation core region 1 overlap. The region Q7 is a region where the magenta density gradation core region 1 and the cyan density gradation fringe region 2 overlap. The region Q8 is a region in which the density gradation fringe regions 2 of cyan and magenta are overlapped. Region Q9 is a region in which neither cyan nor magenta inks are present.

FIG. 8 is a diagram of a table showing the calculation results of the appearance rates of the regions Q1 to Q9 in FIG. 7. In FIG. 8, although the primary color inks C (cyan) and M (magenta) are described, the appearance rate is similarly calculated for the spot color ink. In this table, C is a cyan density gradation region, M is a magenta density gradation region, CM is a region where cyan and magenta density gradation regions overlap, and W is either cyan or magenta. The area where the ink of is not present is shown. In FIG. 8, the appearance rate α1 is the appearance rate of the cyan density gradation core region 1, and the appearance rate α2 is the appearance rate of the cyan density gradation fringe region 2. The appearance rate α0 is the sum of each of the appearance rate α1 and the appearance rate α2 (α0 = α1 + α2). The appearance rate β1 is the appearance rate of the density gradation core region 1 of the magenda, and the appearance rate β2 is the appearance rate of the density gradation fringe region 2 of the magenda. The appearance rate β0 is the sum of each of the appearance rate β1 and the appearance rate β2 (β0 = β1 + β2).

The primary appearance rate of the area Q1 and the area Q2 is α0 * (1-β0) obtained by multiplying the appearance rate α0 at which cyan ink appears by the rate (1-β0) at which magenta ink does not appear. , Indicates the appearance rate of the cyan ink-only region. In this embodiment, * indicates multiplication.
The primary appearance rate of region Q3 and region Q4 is β0 * (1-α0), which is obtained by multiplying the appearance rate β0 at which magenta ink appears by (1-α0), which is the rate at which cyan ink does not appear. , Shows the appearance rate of the ink-only area of the Magenda.

The primary appearance rate from region Q5 to region Q8 is α0 * β0, which is obtained by multiplying the appearance rate α0 at which cyan ink appears by the appearance rate β0 at which magenta ink appears. Indicates the appearance rate of the area where is overlapped.
The primary appearance rate of region Q9 is the rate at which cyan ink does not appear (1-α0) multiplied by the rate at which magenta ink does not appear (1-β0) (1-α0) *. It becomes (1-β0) and shows the appearance rate of the region where both the cyan ink and the magenta ink do not exist.

The secondary appearance rate of the region Q1 indicates the appearance rate of only the density gradation core region 1 of the halftone dots of the cyan ink, and the appearance rate α1 of the density gradation core region 1 is set to the density gradation core region 1. It is a rate divided by the addition result of the appearance rate α1 of and the appearance rate α2 of the density gradation fringe region 2.
The secondary appearance rate of the region Q2 indicates the appearance rate of only the density gradation fringe region 2 of the halftone dots of the cyan ink, and the appearance rate α1 of the density gradation core region 1 is set to the density gradation core region 1. It is a rate obtained by dividing by the addition result of the appearance rate α1 of the above and the appearance rate α2 of the density gradation fringe region 2 and subtracting the division result from 1.

The secondary appearance rate of the region Q3 indicates the appearance rate of only the density gradation core region 1 of the halftone dots of the magenda ink, and the appearance rate β1 of the density gradation core region 1 is set to the density gradation core region 1 of the density gradation core region 1. It is a rate divided by the addition result of the appearance rate β1 of and the appearance rate β2 of the density gradation fringe region 2.
The secondary appearance rate of the region Q4 indicates the appearance rate of only the density gradation fringe region 2 of the halftone dots of the magenda ink, and the appearance rate β1 of the density gradation core region 1 is set to the density gradation core region 1. It is a rate obtained by dividing by the addition result of the appearance rate β1 of and the appearance rate β2 of the density gradation fringe region 2 and subtracting the division result from 1.

The secondary appearance rate of the region Q5 indicates the appearance rate of the overlapping portion of the halftone dot density gradation core region 1 of each of the cyan and magenda inks, and the density gradation core region of the halftone dots of the cyan ink. The rate obtained by dividing the appearance rate α1 of 1 by the addition result of the appearance rate α1 of the density gradation core region 1 and the appearance rate α2 of the density gradation fringe region 2 and the density gradation core region 1 of the halftone dots of the magenta. Is the rate obtained by multiplying the appearance rate β1 of the above by the rate obtained by dividing the appearance rate β1 of the density gradation core region 1 by the appearance rate β1 of the density gradation fringe region 2 and the appearance rate β2 of the density gradation fringe region 2.

The secondary appearance rate of the region Q6 indicates the appearance rate of the overlapping portion of the density gradation core region 1 of the halftone dots of the cyan ink and the density gradation fringe region 2 of the halftone dots of the magenda ink. The rate obtained by dividing the appearance rate α1 of the density gradation core region 1 of the halftone dots of the ink by the addition result of the appearance rate α1 of the density gradation core region 1 and the appearance rate α2 of the density gradation fringe region 2 and the ink of Magenda. The rate obtained by dividing the appearance rate β1 of the halftone dot density gradation core region 1 by the addition result of the appearance rate β1 of the density gradation core region 1 and the appearance rate β2 of the density gradation fringe region 2 is subtracted from 1. Is the rate of the result of multiplying with.

The secondary appearance rate of the region Q7 indicates the appearance rate of the overlapping portion of the density gradation fringe region 2 of the halftone dots of the cyan ink and the density gradation core region 1 of the halftone dots of the magenda ink. The rate obtained by dividing the appearance rate α1 of the density gradation core region 1 of the halftone dots of the ink by the addition result of the appearance rate α1 of the density gradation core region 1 and the appearance rate α2 of the density gradation fringe region 2 was subtracted from 1. The rate and the rate obtained by dividing the appearance rate β1 of the density gradation core region 1 of the halftone dots of the magenda by the addition result of the appearance rate β1 of the density gradation core region 1 and the appearance rate β2 of the density gradation fringe region 2. Is the rate of the result of multiplying with.

The secondary appearance rate of the region Q8 indicates the appearance rate of the overlapping portion of the density gradation fringe region 2 of the halftone dots of the cyan ink and the density gradation fringe region 2 of the halftone dots of the magenta ink. The rate obtained by dividing the appearance rate α1 of the density gradation core region 1 of the halftone dots of the ink by the addition result of the appearance rate α1 of the density gradation core region 1 and the appearance rate α2 of the density gradation fringe region 2 was subtracted from 1. The rate and the rate obtained by dividing the appearance rate β1 of the density gradation core region 1 of the halftone dots of the magenda by the addition result of the appearance rate β1 of the density gradation core region 1 and the appearance rate β2 of the density gradation fringe region 2. Is the rate obtained by multiplying the rate obtained by subtracting 1 from 1.

The secondary appearance rate of the region Q9 indicates the appearance rate of the region in which both the cyan ink and the magenta ink do not exist, and is “1”.

As described above, the expression of the appearance rate used for superimposing the inks to be used is set in advance and stored in the density gradation appearance rate table database 104 as the table shown in FIG.
Returning to FIG. 2, the extended Neugebauer primary color appearance rate calculation unit 1082 determines the density gradation appearance rate table database 104 by combining the type of ink to be superimposed and the command halftone dot area ratio indicating the halftone dots of the ink to be superimposed. Read the formula in the table of FIG.
Further, the extended Neugebauer primary color appearance rate calculation unit 1082 uses the density gradation appearance rate table database 104 to display the appearance rates α1 and α2 of the respective density gradation core regions 1 and density gradation fringe regions 2 of cyan and magenta, respectively. Read β1 and β2.

The extended Neugebauer primary color calculation unit 1081 sets the spectral reflectance of cyan as the background spectral reflectance R ₀ (λ) when cyan is the background and the magenda is superimposed on the cyan, and the magenda appears at the command halftone dot area ratio. _{The spectral reflectance RKM} (λ) of the density gradation region in the overlapping portion is calculated by the equation (1) using the film thickness of the density gradation region of. _{For example, when the extended Neugebauer primary color calculation unit 1081 obtains the spectral reflectance R KM} (λ) in the region Q5, the extended Neugebauer primary color calculation unit 1081 _{determines the density gradation spectral reflectance R im} (λ) at 100% of the film thickness of the cyan ink on the print medium. As the background spectral reflectance R _{0 (λ) of the background, the spectral reflectance R KM} (λ) of the printed portion in the overlapping portion when the film thickness of the magenda ink is 100% is calculated.

Similarly, when the extended Neugebauer primary color calculation unit 1081 _{obtains the spectral reflectance R KM (λ) in the region Q7, the density gradation spectral reflectance R im} (λ) at 50% of the film thickness of the cyan ink on the print medium. Is the underlying spectral reflectance R _{0 (λ), and the spectral reflectance R KM} (λ) when the film thickness of the magenda ink is 100% is calculated. _{Similarly, the spectral reflectance R KM} (λ) is calculated for all combinations of the extended Neugebauer primary colors.
Next, when calculating the extended Neugebauer primary color appearance rate in region Q1, the extended Neugebauer primary color appearance rate calculation unit 1082 has a primary appearance rate α0 * (1-β0) and a secondary appearance rate α1 / (α1 + α2). It is calculated by multiplying. Further, when the extended Neugebauer primary color appearance rate calculation unit 1082 calculates the extended Neugebauer primary color appearance rate in the region Q2, the primary appearance rate α0 * (1-β0) and the secondary appearance rate {1-α1 / ( Obtained by multiplying α1 + α2)}. Each of the regions Q3 and Q4 can be obtained in the same manner as the regions Q1 and Q2 described above, except that cyan is changed to magenta.
When calculating the extended Neugebauer primary color appearance rate in region Q5, the extended Neugebauer primary color appearance rate calculation unit 1082 has a primary appearance rate α0 * β0 and a secondary appearance rate {α1 / (α1 + α2)} * {β1 / ( Obtained by multiplying β1 + β2)}.
When calculating the extended Neugebauer primary color appearance rate in region Q6, the extended Neugebauer primary color appearance rate calculation unit 1082 has a primary appearance rate α0 * β0 and a secondary appearance rate {α1 / (α1 + α2)} * {1-β1. It is calculated by multiplying / (β1 + β2)}.
When calculating the extended Neugebauer primary color appearance rate in region Q7, the extended Neugebauer primary color appearance rate calculation unit 1082 has a primary appearance rate α0 * β0 and a secondary appearance rate {1-α1 / (α1 + α2)} * {β1. It is calculated by multiplying / (β1 + β2)}.
When calculating the extended Neugebauer primary color appearance rate in region Q8, the extended Neugebauer primary color appearance rate calculation unit 1082 has a primary appearance rate α0 * β0 and a secondary appearance rate {1-α1 / (α1 + α2)} * {1. Obtained by multiplying −β1 / (β1 + β2)}.
When calculating the extended Neugebauer primary color appearance rate in region Q9, the extended Neugebauer primary color appearance rate calculation unit 1082 multiplies the primary appearance rate (1-α0) * (1-β0) by the secondary appearance rate 1. Ask for it.

Then, the spectral reflectance calculation unit 1083 multiplies the spectral reflectance of each of the extended Neugebauer primary colors in the regions Q1 to Q9 described above by the extended Neugebauer primary color appearance rate, and adds them for each wavelength.
_{The spectral reflectance calculation unit 1083 determines the first predicted spectral reflectance RD1} (λ) of the printed portion when the halftone dots of the magenta ink are superimposed on the printing medium on which the halftone dots of the cyan ink are printed. Is calculated.

Calculation of Density Gradation Appearance Rate by Spectral Optical Density In addition, the density gradation spectroscopic optical density calculation unit 202 obtains primary colors from the absorption coefficient / scattering coefficient database 106 according to the type of primary color ink supplied from the input unit 101. The absorption coefficient K (λ) and the scattering coefficient S (λ) of the colored layer obtained from the printed portion where the ink is solid and printed on the print medium are read out. Further, the density gradation spectroscopic optical density calculation unit 202 measures spectroscopy for each command net point area ratio from the measurement spectral reflectance database 105 according to the type of primary color ink supplied from the input unit 101 and the type of printing medium. Each of the reflectance Rs (λ) and the background spectral reflectance R ₀ (λ) of the print medium is read out.

Then, the density gradation spectroscopic optical density calculation unit 202 sets the absorption coefficient K (λ) and the scattering coefficient S (λ) of the read primary color ink, the background spectral reflectance R ₀ (λ) of the print medium, and the density gradation. Each of the film thickness coefficient X _{m of} is substituted into the already described equation (1) (Kubelka-Munk's equation), and the spectral reflectance of the density gradation region is defined as the density gradation spectral reflectance R _i1 (λ). , R _i2 (λ), R _i3 (λ), ..., R _im (λ) are calculated.
Further, the density gradation spectroscopic optical density calculation unit 202 obtains each of the obtained density gradation spectral reflectances _Ri1 (λ), _Ri2 (λ), _Ri3 (λ), ..., _Rim (λ). According to the following equation (5), the wavelength gradation spectroscopic optical density _{is converted into OD i1} (λ), OD _i2 (λ), OD _i3 (λ), ..., OD _im (λ), respectively.

Also in density gradation spectroscopic concentration calculator 202, as with density gradation spectral reflectance calculating section 102, the thickness factor X _m of printed ink in (1) (wherein the Kubelka-Munk), printing Based on the printed part where the primary color ink is solidly printed on the medium, it is used as a numerical value indicating the density gradation of the printed part. That is, the film thickness coefficient X _m is arbitrarily set. For example, the solid printed portion having the thickest ink film thickness is set to 100%, the film thickness coefficient is set to 1, and this 1 is set to the film in the density gradation region. Divide into m corresponding to the number of steps of thickness m. For example, if there are five stages of film thickness in the density gradation region indicated by the command halftone dot area ratio, m = 1, 2, 3, 4, 5, and the film thickness coefficient X _m is each density scale. _{X 1} = 1.0, X ₂ = 0.8, X ₃ = 0.6, X ₄ = 0.4, and X ₅ = 0.2, corresponding to the stage of the film thickness in the adjustment region.

As already described, the film thickness coefficient X _m is the Kubelka-Munk equation together with the background spectral reflectance R ₀ (λ) of the print medium, the absorption coefficient K (λ), and the scattering coefficient S (λ). Substituting into Eq. (1), the spectral reflectance of the density gradation region included in the network points of each command network point area ratio is the density gradation spectral reflectance R _i1 (λ), R _i2 (λ), R _i3. Each of (λ), ..., and _Rim (λ) is calculated. Then, each of the density gradation spectral reflectances R _i1 (λ), R _i2 (λ), R _i3 (λ), ..., _Rim (λ) is determined by the concentration gradation spectral optical density OD according to the equation (5). _{It is} converted into i1 (λ), OD _i2 (λ), OD _i3 (λ), ..., OD _im (λ), respectively. The density gradation spectroscopic optical density _{OD i1 (λ), OD i2} (λ), OD i3 (λ), ..., OD im (λ) is used in the calculation model to be described later, a plurality of concentrations floor constituting a halftone It is used as the spectral optical density of each of the tuning regions.

The density gradation appearance rate calculation unit 203 is described by the density gradation spectroscopic optical density calculation unit 202 from the density gradation spectroscopic optical density OD _i1 (λ), OD _i2 (λ), OD _i3 (λ), ..., OD _im ( Read each of λ). Further, the density gradation appearance rate calculation unit 203 reads each of the measured spectral reflectances Rs (λ) for each command halftone dot area ratio from the measured spectral reflectance database 105.
Then, the density gradation appearance rate calculation unit 203 converts each of the measured spectral reflectances Rs (λ) into the measured spectral optical densities ODs (λ) by using the equation (5).
Next, the density gradation appearance rate calculation unit 203 sets the density gradation spectroscopic optical density OD _i1 (λ), OD _i2 (λ), OD _i3 (λ) with respect to the following equation (6) (calculation model). , ..., OD _im (λ) is substituted, and the calculated spectral optical density OD'(s, λ) is calculated by the process described later.

Here, the density gradation appearance rate calculation unit 203 changes the numerical value of the appearance rate (ratio of the area of the density gradation region of each density gradation constituting the halftone dots in the printed portion of the paper) in the equation (6). While doing so, the calculated spectral optical density OD'(s, λ) is calculated. Then, the density gradation appearance rate calculation unit 203 has a mean square error between each of the calculated spectral optical densities OD'(s, λ) calculated by the following equation (7) and the measured spectral optical densities ODs (λ). RMSE is obtained in a predetermined wavelength range for each command network point area ratio. The density gradation appearance rate calculation unit 203 obtains the appearance rate of each of the density gradation regions where the mean square error between the calculated spectral optical density OD'(s, λ) and the measured spectral optical density ODs (λ) is the smallest. .. Here, s is the command halftone dot area ratio.

In the above equation (7), the density gradation appearance rate calculation unit 203 calculates the calculated spectral optical density OD'(s, λ) and the measured spectral optical density ODs (λ) according to the step size in which the wavelength λ is divided into n from 380 nm to 730 nm. ) And the mean square error RMSE obtained by adding the square of the error to each wavelength λ is obtained for each command network point area ratio.

Then, the density gradation appearance rate calculation unit 203 determines the appearance rate functions a ₁ (s), a ₂ (s), a ₃ (s) of each density gradation region according to the appearance rate of each density gradation region. _..., seek _a m (s). Here, the density gradation appearance rate calculation unit 203 uses the obtained appearance rate for each density gradation region, and fits this appearance rate to a quadratic function of the command halftone dot area ratio s, and the appearance rate. You may ask for a function. The density gradation appearance rate calculation unit 203 sets the appearance rate functions a ₁ (s), a ₂ (s), a ₃ (s), ..., _Am (s) of the obtained density gradation regions in the density scale. The key appearance rate table database 204 is written and stored. For the appearance rate functions a ₁ (s), a ₂ (s), a ₃ (s), ..., _Am (s), the calculation model of Eq. (6) is the same as the explanation in the spectral reflectance prediction unit 108. It is a function for obtaining the appearance rate of the density gradation region used in the above, and is used for modeling the structure of halftone dots by gravure printing as described in FIG.

As described above, the density gradation appearance rate calculation unit 203 uses the calculation model of Eq. (6) to print the density contained in the halftone dots in the printed portion where the ink (primary color ink) based on the command halftone dot area ratio is printed. For each gradation, the density gradation spectroscopic optical density OD _im (λ) of the density gradation and the appearance rate functions of the density gradation a ₁ (s), a ₂ (s), a ₃ (s), ..., _Am The result of multiplying with (s) is added to calculate the spectral optical density of the printed portion of the command halftone dot area ratio.

Furthermore, density gradation appearance ratio calculating section 203, the appearance rate shows the appearance of each gray scale region in command area coverage of gray scale region determined function a _m a _(s), the concentration gradation incidence The table database 204 is written and stored in correspondence with the density gradation spectroscopic optical density in the density gradation region. Similarly, density gradation appearance ratio calculating unit 203, with respect to each of the other primary color inks, the appearance rate function representing the occurrence of each gray scale region in command area coverage of gray scale region a _m (S) is written and stored in the density gradation appearance rate table database 204.

Moreover, in the case of spot color ink produced by mixing the primary color ink at a predetermined ratio, using the appearance rate function a _m of the density gradation region of the primary color inks as described above _(s) is read out from the density gradation occurrence rate table database 204 .. Here, may be used either occurrence rate function a _m primary ink mixing in spot ink _(s), also the incidence of each primary color ink to mix function a _{m (s)} is in accordance with the blending ratio It may be used in combination.
_{In the case of this spot color ink, the scattering coefficient St} (λ) and the absorption coefficient of the spot color ink are described in the above-described equation (4) according to the ratio of the primary color inks to be mixed, as described in the spectral reflectance prediction unit 108. Calculate K _t (λ).

In the above equation (4), each of the coefficient α and the coefficient β is a coefficient indicating the mixing ratio of the primary color ink # 1 and the primary color ink # 2. _{The absorption coefficient K 1} (λ) of the primary color ink # 1 is multiplied by the coefficient α, the absorption coefficient K ₂ of the primary color ink # 2 is multiplied by the coefficient β, and the added value is the absorption coefficient K of the special color ink. _{It is set to t} (λ). _{Similarly, the scattering coefficient S 1} (λ) of the primary color ink # 1 is multiplied by the coefficient α, the scattering coefficient S ₂ (λ) of the primary color ink # 2 is multiplied by the coefficient β, and the added value is calculated. The scattering coefficient _St (λ) of the special color ink is used.
From the absorption coefficient / scattering coefficient database 106, the density gradation spectroscopic optical density calculation unit 202 determines the scattering coefficients S1 (λ) and S2 (λ) of the primary color inks # 1 and the primary color inks # 2, which constitute the spot color ink, respectively. And the absorption coefficients K1 (λ) and K2 (λ), respectively. Further, the density gradation spectroscopic optical density calculation unit 102A reads out the background spectral reflectance R0 (λ) of the print medium from the measurement spectral reflectance database 105.
Next, the density gradation spectroscopic optical density calculation unit 202 includes the calculated scattering coefficient St (λ) and absorption coefficient Kt (λ) of the special color ink, the background spectral reflectance R0 (λ) of the print medium, and the density gradation. By substituting each of the film thickness coefficient Xm of (1) into the above equation (1), the spectral reflectance of the density gradation region is the density gradation spectral reflectance Ri1 (λ), Ri2 (λ), Ri3 (λ). , ..., Rim (λ) is calculated.
The density gradation spectroscopic optical density calculation unit 202 has calculated the density gradation spectral reflectance Ri1 (λ),
For each of Ri2 (λ), Ri3 (λ), ..., Rim (λ), the density gradation optical density ODi1 (λ), ODi2 (λ), ODi3 ( λ), ノ, ODi
Convert to m (λ) respectively.

Operation of Spectral Optical Density Prediction Unit 111 Next, the spectroscopic optical density prediction unit 111 includes an extended Neugebauer primary color calculation unit 1111, an extended Neugebauer primary color appearance rate calculation unit 1112, a spectroscopic optical density calculation unit 1113, and a spectral reflectance calculation unit 1114. I have.
The extended Neugebauer primary color calculation unit 1111 determines the ink to be the base (primary color ink or the special color ink) and the ink to be printed on the surface of the base according to the order of the colors to be superimposed. Further, the extended Neugebauer primary color calculation unit 1111 reads the command halftone dot area ratio of each of the inks to be superimposed from the input unit 101.

Further, the extended Neugebauer primary color calculation unit 1111 reads the scattering coefficient S (λ) and the absorption coefficient K (λ) of the ink (primary color ink or spot color ink) printed on the underlying ink.
Next, the extended Neugebauer primary color calculation unit 1111 is _{placed on the density gradation spectral reflectance Rim} (λ) of the base ink and the base ink according to the equation (1), as already described in FIG. Substituting each of the scattering coefficient S (λ) and reflectance K (λ) _{of the ink to be printed and the film thickness coefficient X m} of the density gradation region, the density of halftone dots printed on the underlying ink. The gradation spectral reflectance _Rim (λ) is calculated.

_{Here, the extended Neugebauer primary color calculation unit 1111 calculates the density gradation spectral reflectance Rim} (λ) of the halftone dots of the ink printed on the halftone dots of the base ink described above, and calculates the halftone dots of the base ink. This is performed in all combinations of the overlapping portion of the density gradation area in the above and the density gradation area of the halftone dots of the ink printed on the halftone dots of the underlying ink. Then, the extended Neugebauer primary color calculation unit 1111 calculates the density gradation spectral reflectance _Rim (λ) of the ink printed on the halftone dots of the obtained underlying ink by the density gradation spectroscopic optics according to the equation (5). Convert to concentration OD _im (λ). The extended Neugebauer primary color calculation unit 1111 _{writes the obtained density gradation spectroscopic optical density OD im} (λ) in the Neugebauer primary color table of the temporary storage unit 125 and stores it.

Returning to FIG. 2, the extended Neugebauer primary color appearance rate calculation unit 1112 has the same density gradation region of the base ink and the density gradation region of the ink printed on the base ink as described in FIG. 7. Calculate the percentage of overlapping appearance rates.

Further, the expression of the appearance rate used for superimposing the inks (primary color ink or special color ink) to be used is a density gradation appearance rate table as a table of appearance rates shown in FIG. 8 as explained in the spectral reflectance prediction unit 108. It is written and stored in database 204.
The extended Neugebauer primary color appearance rate calculation unit 1112 sets the table of FIG. 8 of the density gradation appearance rate table database 204 by each combination of the type of ink to be superimposed and the command halftone dot area ratio indicating the halftone dots of the ink to be superimposed. Read the formula of.
Further, the extended Neugebauer primary color appearance rate calculation unit 1112 obtains the appearance rates α1 and α2 of the respective density gradation core regions 1 and density gradation fringe regions 2 of cyan and magenta from the density gradation appearance rate table database 204. Read β1 and β2.

Further, when the cyan is the background and the magenda is superimposed on the cyan, the extended Neugebauer primary color calculation unit 1111 appears at the command halftone dot area ratio with _{the spectral reflectance of cyan as the background spectral reflectance R 0 (λ) of the background. The spectral reflectance RKM} (λ) of the density gradation region in the overlapping portion is calculated by the equation (1) using the film thickness of the density gradation region of the magenda. _{For example, when the extended Neugebauer primary color calculation unit 1111 obtains the spectral reflectance R KM} (λ) in the region Q5, the extended Neugebauer primary color calculation unit 1111 _{determines the density gradation spectral reflectance R im} (λ) at 100% of the film thickness of the cyan ink on the print medium. As the base spectral reflectance R _{0 (λ) of the base, the spectral reflectance R KM} (λ) of the printed portion at the overlapping portion when 100% of the film thickness of the ink of Magenda is overlaid on the base is calculated. Then, the extended Neugebauer primary color calculation unit 1111 _{converts the calculated spectral reflectance R KM} (λ) into the spectral optical density OD _KM (λ) by the equation (5).

Similarly, when the extended Neugebauer primary color calculation unit 1111 _{obtains the spectral reflectance R KM (λ) in the region Q7, the density gradation spectral reflectance R im} (λ) at 50% of the film thickness of the cyan ink on the print medium. Is the underlying spectral reflectance R _{0 (λ), and the spectral reflectance R KM} (λ) when the film thickness of the magenda ink is 100% is calculated. Then, the extended Neugebauer primary color calculation unit 1111 _{converts the calculated spectral reflectance R KM} (λ) into the spectral optical density OD _KM (λ) by the equation (5). _{Similarly, the spectral optical density OD KM} (λ) is calculated for all combinations of the extended Neugebauer primary colors.
When calculating the extended Neugebauer primary color appearance rate in region Q1, the extended Neugebauer primary color appearance rate calculation unit 1112 multiplies the primary appearance rate α0 * (1-β0) by the secondary appearance rate α1 / (α1 + α2). Ask for it. Further, when the extended Neugebauer primary color appearance rate calculation unit 1112 calculates the extended Neugebauer primary color appearance rate in the region Q2, the primary appearance rate α0 * (1-β0) and the secondary appearance rate {1-α1 / ( Obtained by multiplying α1 + α2)}. Each of the regions Q3 and Q4 can be obtained in the same manner as the regions Q1 and Q2 described above, except that cyan is changed to magenta.
When calculating the extended Neugebauer primary color appearance rate in region Q5, the extended Neugebauer primary color appearance rate calculation unit 1112 has a primary appearance rate α0 * β0 and a secondary appearance rate {α1 / (α1 + α2)} * {β1 / ( Obtained by multiplying β1 + β2)}.
When calculating the extended Neugebauer primary color appearance rate in region Q6, the extended Neugebauer primary color appearance rate calculation unit 1112 has a primary appearance rate α0 * β0 and a secondary appearance rate {α1 / (α1 + α2)} * {1-β1. It is obtained by multiplying / (β1 + β2)}.
When calculating the extended Neugebauer primary color appearance rate in region Q7, the extended Neugebauer primary color appearance rate calculation unit 1112 has a primary appearance rate α0 * β0 and a secondary appearance rate {1-α1 / (α1 + α2)} * {β1. It is calculated by multiplying / (β1 + β2)}.
When calculating the extended Neugebauer primary color appearance rate in region Q8, the extended Neugebauer primary color appearance rate calculation unit 1112 has a primary appearance rate α0 * β0 and a secondary appearance rate {1-α1 / (α1 + α2)} * {1. Obtained by multiplying −β1 / (β1 + β2)}.
When calculating the extended Neugebauer primary color appearance rate in region Q9, the extended Neugebauer primary color appearance rate calculation unit 1112 multiplies the primary appearance rate (1-α0) * (1-β0) by the secondary appearance rate 1. Ask for it.
Then, the spectroscopic optical density calculation unit 1113 multiplies and adds the optical densities of the extended Neugebauer primary colors in the regions Q1 to Q9 described above by the extended Neugebauer primary color appearance rate.
The spectral optical density calculation unit 1113 calculates the predicted optical density OD (λ) of the printed portion when the halftone dots of the magenta ink are superimposed on the printing medium on which the halftone dots of the cyan ink are printed.

Then, the spectral optical density calculation unit 1113 multiplies each spectral optical density of the extended Neugebauer primary colors in the regions Q1 to Q9 described above by the appearance rate of the extended Neugebauer primary colors, and adds them for each wavelength.
Spectroscopic optical density calculating section 1113 calculates the relative print media halftone cyan ink is printed, predicted spectral printing portion at the time of printing by overlapping dots of ink magenta optical density OD D _(λ) do.

Spectral reflectance calculating unit 1114, the spectral optical density calculation unit 1113 to calculate predicted spectral optical density OD _D a (lambda), using the following equation (8), into a second prediction spectral reflectances _{R D2} (lambda) do.

-Operation of the mixing prediction unit 114 The mixing prediction unit 114 reads out the weighting coefficient w to be multiplied by _{the first predicted spectral reflectance R D1} (λ) and the second predicted spectral reflectance R _{D2 (λ) from the prediction parameter database 126.} .. For example, the mixing prediction unit 114 _{adds wR D1} (λ) and (1-w) R _D2 (λ) to obtain the integrated predicted spectral reflectance _RD (λ). Then, the mixing prediction unit 114 outputs the integrated predicted spectral reflectance R _D (λ) as the predicted spectral reflectance R (λ) to the color profile generation unit 13.

<Generation of color profile>
Then, the color profile generation unit 13 determines the observation light source based on the predicted spectral reflectance R (λ), calculates the tristimulus value XYZ, the CIELAB value, and the like, and creates a color prediction table for predicting the reproduced color. do. That is, the color profile generation unit 13 reproduces the information of the input data (CMY value in this embodiment) that is the target of the color prediction process and the reproduction color predicted based on the predicted spectral reflectance R (λ). Create a color prediction table as a color profile that associates with color information. In this embodiment, the color profile generation unit 13 creates this color prediction table in a known ICC (International Color Consortium) profile format, writes it in the storage unit 18, and stores it.

FIG. 9 is a flowchart illustrating an operation example of the color profile generation process by the color prediction model generation unit 12 and the color profile generation unit 13 in the present embodiment.

Step S401:
Extended Neugebauer primary color appearance ratio calculating unit 1082, the Neugebauer primary color table in the temporary storage unit 125, reads the spectral reflectance of the Neugebauer primary color features inks overlap region R _{KM (λ).
Similarly, the extended Neugebauer primary color appearance rate calculation unit 1112 reads the spectral optical density OD KM} (λ) of the Neugebauer primary color of the spot color ink in the overlapping region from the Neugebauer primary color table of the temporary storage unit 125.

Step S402:
_{The mixing prediction unit 114 integrates the first predicted spectral reflectance R D1} (λ) predicted by the spectral reflectance prediction unit 108 _{and the second predicted spectral reflectance R D2} (λ) predicted by the spectral optical density prediction unit 111. At that time, the weighting coefficient w to be multiplied by each of the first predicted spectral reflectance R _D1 (λ) and the second predicted spectral reflectance R _D2 (λ) is read out from the prediction parameter database 126.

Step S403:
Next, the extended Neugebauer primary color appearance rate calculation unit 1082 extracts an uncalculated command halftone dot area ratio from the matrix of the command halftone dot area ratios of the overlapping inks in the color prediction table in the temporary storage unit 125.
Then, the extended Neugebauer primary color appearance rate calculation unit 1082 sets the combination of the extracted command halftone dot area ratios as the calculation target. The above-mentioned processing may be performed by the extended Neugebauer primary color appearance rate calculation unit 1112.

Step S404:
_{The spectral reflectance prediction unit 108 calculates the first predicted spectral reflectance RD1} (λ) by combining the command halftone dot area ratios.
The spectral optical density prediction unit 111 _{calculates the second predicted spectral reflectance R D2} (λ) by combining the command halftone dot area ratios.

Further, the mixing prediction unit 114 integrates the weighting coefficients w and (1-w) read in step S402 into _{the first predicted spectral reflectance R D1} (λ) and the second predicted spectral reflectance R _{D2 (λ).} The integrated predicted spectral reflectance _RD (λ) _{is obtained by adding wR D1} (λ) and (1-w) _{RD2 (λ).} Further, the color measurement value is calculated by setting the spectral distribution of the observation light source and the standard observer for the calculated integrated predicted spectral reflectance _{RD (λ).}

Step S405:
Then, the mixing prediction unit 114 makes the calculated color measurement values correspond to the combination of the command halftone dot area ratios of the inks (spot color inks or primary color inks) to be superimposed, and writes and stores them in the color prediction table of the storage unit 18.

Step S406:
The extended Neugebauer primary color appearance rate calculation unit 1082 determines whether or not the calculation _{of the integrated predicted spectral reflectance RD} (λ) of all combinations of command halftone dot area ratios in the color prediction table of the storage unit 18 is completed. ..
Then, when the calculation of the integrated predicted spectral reflectance _RD (λ) of the combination of all the command halftone dot area ratios is completed, the extended Neugebauer primary color appearance rate calculation unit 1082 proceeds to step S407. On the other hand, the extended Neugebauer primary color appearance rate calculation unit 1082 proceeds to step S403 when the calculation _{of the integrated predicted spectral reflectance RD (λ) of all combinations of command halftone dot area ratios is not completed.} The above-mentioned processing may be performed by the extended Neugebauer primary color appearance rate calculation unit 1112.

Step S407:
The color profile generation unit 13 reads the data in the color prediction table of the storage unit 18, converts it into a known ICC profile format, and writes the converted color prediction profile data in the storage unit 18 for storage.

As described above, according to the present embodiment, the absorption characteristics and scattering characteristics of the spot color ink are estimated from the primary color ink, the spectral reflectance of the spot color ink is calculated, and the spectroscopy of the overlapping region when the spot color ink is overprinted is dispersed. The reflectance can be obtained.
Therefore, according to the present embodiment, it is possible to predict the color of the reproduced color in the printed matter in which the spot color ink is overprinted in printing such as gravure printing having both the area modulation gradation expression and the density modulation gradation expression. It can be easily performed with high accuracy.

Further, according to this embodiment, the spectral reflectance of the expanded Neugebauer primaries, a first prediction spectral reflectances R _D1 calculated from its appearance ratio _(lambda), the spectral optical density of the extended Neugebauer primaries, from its appearance ratio calculated second predicted spectral reflectance R _D2 and _(lambda), for mixing the pre-determined weighting factor w, mixed predicted spectral reflectance as more predicted spectral reflectance close to the spectral reflectance of the measured value R _{W (lambda} ) Can be obtained as the predicted spectral reflectance R (λ).

<Operation explanation of print color adjustment system>
FIG. 10 is a flowchart illustrating an operation example of an adjustment process in which the printing color of the printing device (for example, an inkjet printer) is the same as the color of the printed matter of the printing machine by the printing color adjusting system in the present embodiment.
Step S501
The user measures the color of the solid color patch of the ink used when the printing machine prints the printed matter, and obtains the color measurement value of each ink. Then, the user inputs each color measurement value of the measured ink to the print color adjustment system 1 from the input means (keyboard, touch panel, etc.).
Further, the user inputs each image data (data of the command halftone dot area ratio of each pixel) of the printed matter plate to the print color adjustment system 1 from an external device.

Step S502:
The input control unit 11 outputs the color measurement value supplied from the input means to the color prediction model generation unit 12. Further, the input control unit 11 writes and stores the image data of the printed matter supplied from the input means in the storage unit 18.
Then, the color prediction model generation unit 12 generates a color prediction model (color prediction table) as described above, and writes and stores the generated color prediction model in the storage unit 18.

Step S503:
The color profile generation unit 13 refers to the color prediction model (color prediction table) of the storage unit 18 and displays each of the predicted spectral reflectances R (λ) corresponding to the combination of the command halftone dot area ratios of the inks. It is converted into a known ICC profile format, and the data of the converted color profile (color prediction profile) is written in the storage unit 18 and stored.

Step S504:
The adjustment control unit 14 displays an image for extracting a partial image as a reference image for evaluating the color of the printed matter printed by the printing device from the image in the image data on the display screen of the display unit 16. This reference image is a partial image of a portion including a color to be expressed, particularly in an image of image data.
Then, the adjustment control unit 14 cuts out the area of the partial image selected by the user from the image data as the reference image in the image of the image data displayed on the display screen of the display unit 16.

Step S505:
The control value generation unit 15 predicts the combination of the command halftone dot area ratios of each ink in each of the pixels of the reference image cut out from the image data of the printed matter by the adjustment control unit 14 with reference to the color profile of the storage unit 18. Convert to color measurement value.
Further, the control value generation unit 15 refers to the device color profile of the printing device of the storage unit 18, converts the expected color measurement value of each pixel of the reference image into the control value of the printing device, and writes it in the storage unit 18. Remember.
Then, the print data output unit 17 reads the control value of each pixel of the reference image from the storage unit 18, and outputs the control value for printing the printed matter of the read reference image to the printing device.

Step S506:
As a result, the user observes and compares the colors of the printed matter of the reference image printed by the printing device and the region corresponding to the reference image in the printed matter of the printing machine. Then, the user finds that the color of the printed matter of the reference image printed by the printing device is within the difference of its own tolerance with respect to the color of the area corresponding to the reference image in the printed matter of the printing machine (that is, it matches). It is judged whether or not it is.

Step S507:
When the user determines that the color of the printed matter of the reference image printed by the printing device and the color of the region corresponding to the reference image in the printed matter of the printing machine match, the process proceeds to step S508.
On the other hand, if it is determined that the color of the printed matter of the reference image printed by the printing device and the color of the region corresponding to the reference image in the printed matter of the printing machine do not match, the process proceeds to step S509.

Step S508:
In order to print a predetermined number of sheets, the user inputs the number of prints to the print color adjustment system 1 via the input means.
As a result, the control value generation unit 15 predicts the combination of the command halftone dot area ratio of each ink in each of the image data of the printed matter of the printing machine with reference to the color profile of the storage unit 18. It is converted into a value, stored in the storage unit 18, and output to the print data output unit 17.
Then, the print data output unit 17 outputs the control value of the image data supplied from the control value generation unit 15 to the printing device, and prints the number of printed matter to be printed.

Step S509:
When the color difference between the printed matter of the reference image of the printing device and the printed matter of the printing machine exceeds the permissible range, the user performs the parameter change processing in the color prediction model. This change process will be described in detail later.
Then, the adjustment control unit 14 generates a multi-step adjustment parameter for each of the adjustment target parameters based on the type of the adjustment target parameter input by the user from the input means and the adjustment ratio, and the color prediction model. Output to the generation unit 12 to generate a new color prediction model.

As a result, the color prediction model generation unit 12 generates a color prediction model corresponding to each of the plurality of adjustment parameters in multiple stages. For example, when there are two types of parameters to be adjusted and these parameters are adjusted in five stages, the color prediction model generation unit 12 has 25 color prediction models corresponding to a combination of 5 × 5 = 25. To generate.
Then, the color prediction model generation unit 12 writes the generated color prediction model in the storage unit 18 and stores it.

Step S510:
The color profile generation unit 13 refers to the adjusted color prediction model in the storage unit 18 and generates a color profile corresponding to each of the color prediction models of the combination of the parameters to be adjusted.
Then, the color profile generation unit 13 writes and stores each of the generated color profiles in the storage unit 18.

Step S511:
The control value generation unit 15 sets the combination of the command halftone dot area ratios of each ink in each of the pixels of the reference image cut out from the image data of the printed matter by the adjustment control unit 14, and each of the adjusted color profiles of the storage unit 18. Is sequentially referred to and converted to the expected color measurement value for each color profile. That is, the control value generation unit 15 generates the data of the reference image converted into the expected color measurement value for each color profile.
Further, the control value generation unit 15 refers to the device color profile of the printing device of the storage unit 18, converts the expected color measurement value of each pixel in the data of each reference image into the control value of the printing device, and stores the storage unit 18. Write to and memorize. As a result, the control value generation unit 15 generates control value data of reference images having different numbers of color profiles.
Then, the print data output unit 17 reads out the control value of each pixel of the reference image from the storage unit 18, and outputs the control value of each read reference image to the printing device.

As a result, the process shifts to step S506, and the user observes and compares the colors of each of the printed matter of the plurality of reference images printed by the printing device and the region corresponding to the reference image in the printed matter of the printing machine. do. Then, the user finds that the color of any of the printed matter of the reference image printed by the printing device is within the difference in his / her tolerance with respect to the color of the region corresponding to the reference image in the printed matter of the printing machine (that is,). , Matches).
Then, in step S507, if there is a reference image whose color matches the printed matter of the printing machine, the process proceeds to S508, and if there is no matching reference image, the process proceeds to step S509.

<Parameter adjustment of color prediction model>
When the user compares the colors of the printed matter of the printing machine and the printed matter of the printing device and determines that they do not match, the parameters of the color prediction model are adjusted as described above.
There are the following types of parameters to be adjusted, depending on the item to be adjusted.

a. When adjusting the print density The parameter to be adjusted is the change of the numerical value _{of the film thickness coefficient X m} in the Kbelka-Munch equation shown in Eq. (1). If you want to increase the color density of the ink to be adjusted, increase the film thickness coefficient X _m , while if you want to decrease the color density of the ink to be adjusted, decrease the _{film thickness coefficient X m.} When changing in multiple stages, the adjustment control unit 14 changes the film thickness at a predetermined ratio. For example, in the case of a darkening change, if the current film thickness coefficient is adjusted in 5 stages, the film thickness coefficient is X _m. Then, 1.05, 1.10, 1.25, 1.20, 1.25, etc. are multiplied to generate a slightly changed adjustment parameter. Further, in the case of a change to be thinned, the adjustment control unit 14 adjusts the current film thickness coefficient in five stages, 0.95, 0.90, 0.85, 0 with respect _{to the film thickness coefficient X m.} Multiply by .80, 0.75, etc. and use as a parameter for adjustment with slight changes. The color prediction model generation unit 12 generates a color prediction model in which the color density of the ink to be adjusted is adjusted in multiple stages.
The above ratio may be input by the user by an input means, or may be set in advance.

b. When adjusting the color value of printing If you want to change the color value of one of the inks on the print medium, change the ink itself selected by the color measurement value of the solid printing of the ink used for the printed matter to another ink. When the user inputs an instruction to change this parameter, the spot color ink spectral reflectance calculation unit 121 selects an ink (spot color ink) having a color measurement value close to that of solid printing, and the color measurement value is close to that of the ink (spot color ink). A plurality of the extracted inks are sequentially extracted from the approximate color database 128, and the plurality of extracted inks are displayed on the display screen of the display unit 16. In order to change the color value of the ink in multiple stages, the user selects a number of spot color inks in multiple stages from the displayed spot color inks.

From this, the adjustment control unit 14 changes the blending ratio (values of α and β) of the blended inks in the spot color ink in the formula (4) with respect to each of the selected spot color inks, and changes the blending ratio (values of α and β) of the spot color ink. The absorption coefficient K (λ) and the scattering coefficient S (λ) of the above were adjusted, the spectral reflectance obtained for each compounding ratio was calculated, and the predicted color measurement value obtained from this spectral reflectance was used for printing the printed matter. Select a blending ratio that is the same as the color measurement value for solid ink printing. The color prediction model generation unit 12 generates a color prediction model by using the selected spot color ink and the absorption coefficient K (λ) and the scattering coefficient S (λ) of the spot color ink according to the blending ratio of the ink. As a result, the color prediction model generation unit 12 generates a color prediction model corresponding to a combination of a plurality of spot color inks selected by the user and the absorption coefficient K (λ) and the scattering coefficient S (λ) of the spot color inks. ..

c. When adjusting the gradation characteristics of printing Among the functions in each of the appearance rate functions a ₁ (s), a ₂ (s), a ₃ (s), ..., _Am (s) in the following equation (9) The parameters are changed to adjust the shape and position of each of the appearance rate functions shown in FIG. 3 (a).
Thereby, the gradation characteristic of each ink density stage can be arbitrarily changed. The parameters in this function are changed in a plurality of stages, a table corresponding to FIG. 7 of a plurality of gradation characteristics is created, and a color prediction model corresponding to each table is generated.

d. In the configuration superposed ink case of adjusting to match the trapping state of the printed material to the printing device, when determining the density gradation spectral reflectance R _KM of ink overlap the upper side (1) by the formula of Kubelka-Munk formula , Change the film thickness coefficient X _m. The change of the film thickness coefficient X _m is the same as in the case of “a. When adjusting the printing density” described above. Then, the color prediction model generation unit 12 adjusts the color density of the ink on the upper side of the overlap to be adjusted in multiple stages, and generates a color prediction model in which the trapping state is changed.

e. When adjusting the superposition deviation of each plate in the printed matter to the printing device The adjustment control unit 14 reads out the image data of the plates stored in the storage unit 18, synthesizes each plate, and images the printed matter. When generating data, the plates are not completely matched and overlapped, but are overlapped with a predetermined amount of deviation (small deviation). As a result, the combination of command halftone dot area ratios of each pixel differs depending on the overlap of each plate. A plurality of different amounts of deviation generate a number of image data corresponding to this number.
Then, the control value generation unit 15 converts the combination of the command halftone dot area ratios of the inks in each pixel of the image data of the plurality of printed matter into the expected color measurement value by referring to the color profile of the storage unit 18. do. The control value generation unit 15 refers to the device color profile of the printing device of the storage unit 18, converts each expected color measurement value of the pixel into a control value of the printing device, and writes and stores the expected color measurement value in the storage unit 18.

f. When adjusting the print device to match the graininess of the printed matter The adjustment control unit 14 performs a filter process for superimposing noise on the image data, for example, a filter process for superimposing Gaussian noise on the image data to obtain pixels in the image data. The area ratio of each commanded halftone dot is changed, and granular noise is superimposed on the image. The shape of the superimposed noise can be changed in multiple stages to obtain a plurality of adjusted image data.
Then, the control value generation unit 15 converts the combination of the command halftone dot area ratios of the inks in each pixel of the image data of the plurality of printed matter into the expected color measurement value by referring to the color profile of the storage unit 18. do. The control value generation unit 15 refers to the device color profile of the printing device of the storage unit 18, converts each expected color measurement value of the pixel into a control value of the printing device, and writes and stores the expected color measurement value in the storage unit 18.

According to the present embodiment, as described above, a mesh dot printed matter that reproduces the color of an image by printing ink in a mesh dot shape on a printing medium by a method such as gravure printing, screen printing, and offset printing with a printing machine. When printing the same image data in the same color with a simple printing machine (printing device) such as an inkjet printer or digital printing machine, printing is performed by adjusting the parameters of the color prediction model that models the mesh dot shape. By changing the control value of the printing device by adjusting the color of the printed matter of the device, it is possible to adjust the color of the printed matter of the printing device corresponding to the ink unit on which the net dot printed matter is printed. When adjusting the printing corresponding to the predetermined ink of the dot print, the color of the color to be adjusted in the printed matter of the printing device is adjusted so as not to affect the colors of the inks other than the predetermined ink. It can be done easily.

Further, according to the present embodiment, when it is desired to add a small amount of printed matter printed by a commercial printing machine capable of printing in a large amount, the small amount printing is not a costly commercial printing machine, but an inkjet printer or digital printing. Using a simple printing machine such as a machine, it is possible to print a printed matter similar to the printed matter printed by a commercial printing machine, and it is possible to add a small amount of printed matter at low cost and in real time.
Further, according to the present embodiment, when the printed matter printed by the commercial printing machine capable of printing in large quantities is insufficient, the printed matter similar to the printed matter printed by the commercial printing machine can be produced at low cost and in real time. It becomes possible to print using a simple printing machine, and it is not necessary to anticipate a shortage and print extra to keep the stock as in the conventional case.

Further, in the present embodiment, the absorption characteristics and scattering characteristics of the special color ink are estimated from the primary color ink, the spectral reflectance of the special color ink is calculated, and the spectral reflectance of the overprinted region of the special color ink of the printed matter is obtained. A color prediction model that estimates the color measurement value of each pixel of the printed matter is used, but any configuration may be used as long as it is a color prediction model that can estimate the color measurement value from the combination of command halftone dot area ratios. ..

A program for realizing the function of the print color adjustment system of FIG. 1 in the present invention is recorded on a computer-readable recording medium, and the program recorded on the recording medium is read into the computer system and executed. You may control the color adjustment of the printed matter to be printed by the printing device. The term "computer system" as used herein includes hardware such as an OS and peripheral devices.
Further, the "computer system" shall also include a WWW system provided with a homepage providing environment (or display environment). Further, the "computer-readable recording medium" refers to a portable medium such as a flexible disk, a magneto-optical disk, a ROM, or a CD-ROM, or a storage device such as a hard disk built in a computer system. Furthermore, a "computer-readable recording medium" is a volatile memory (RAM) inside a computer system that serves as a server or client when a program is transmitted via a network such as the Internet or a communication line such as a telephone line. In addition, it shall include those that hold the program for a certain period of time.

Further, the program may be transmitted from a computer system in which this program is stored in a storage device or the like to another computer system via a transmission medium or by a transmission wave in the transmission medium. Here, the "transmission medium" for transmitting a program refers to a medium having a function of transmitting information, such as a network (communication network) such as the Internet or a communication line (communication line) such as a telephone line. Further, the above program may be for realizing a part of the above-mentioned functions. Further, a so-called difference file (difference program) may be used, which can realize the above-mentioned functions in combination with a program already recorded in the computer system.

1 ... Print color adjustment system 11 ... Input control unit 12 ... Color prediction model generation unit 13 ... Color profile generation unit 14 ... Adjustment control unit 15 ... Control value generation unit 16 ... Display unit 17 ... Print data output unit 18 ... Storage unit 101 ... Input unit 102 ... Density gradation spectral reflectance calculation unit 103, 203 ... Density gradation appearance rate calculation unit 104, 204 ... Density gradation appearance rate table database 105 ... Measurement spectral reflectance database 106 ... Absorption coefficient / scattering coefficient database 107 ... Absorption coefficient / scattering coefficient calculation unit 108 ... Spectral reflectance predictor 110 ... Output unit 111 ... Spectral optical density prediction unit 112 ... Weight coefficient calculation unit 113 ... Weight coefficient database 114 ... Mixing prediction unit 121 ... Special color ink spectral reflectance Calculation unit 122 ... Special color ink blending ratio determination unit 123 ... Special color ink density gradation appearance rate calculation unit 125 ... Temporary storage unit 126 ... Prediction parameter database 128 ... Approximate color database 202 ... Concentration gradation spectral optical density calculation unit 1081, 1111 ... Extended Neugebauer primary color calculation unit 1082, 1112 ... Extended Neugebauer primary color appearance rate calculation unit 1083, 1114 ... Spectral reflectance calculation unit 1113 ... Spectral optical density calculation unit

Claims (8)

Prediction of the color of the printed matter printed from the command values of the area-modulated gradation and the density-modulated gradation from the color measurement values of each solid print of the ink used for the printed matter printed by the area-modulated gradation and the density-modulated gradation. A color profile generation unit that generates a color profile of a first printing machine that prints the printed matter by using a print color prediction model for obtaining a value.
From the color profile, the predicted value of the color corresponding to the command value of each dot in the image data of the printed matter is obtained, the predicted value is used as the color information of the color of the printed matter, and the color information is used as the color profile of the second printing machine. A print control unit that converts the color into a control value and outputs it to the second printing machine .
The parameters used for the calculation of the prediction of the predicted color in the printing color prediction model are adjusted, and the plurality of the printing color prediction models are generated corresponding to the parameters adjusted in a plurality of stages to generate the plurality of the color profiles. and an adjustment controller to generate,
The print color prediction model uses the absorption coefficient and the scattering coefficient of each solid printing of the ink to predict the predicted value when the ink is overprinted, and determines the spectral reflectance at each dot of the printed matter. It includes a process obtained by Munk's formula, and uses the color value of the ink for solid printing in the Kubelka Munk's formula as the parameter.
Print color adjustment system comprising a call. Before SL print controller, a print color adjustment system of claim 1, each control value obtained from each of the color profile, and outputs the second printing press. The print color adjustment system according to claim 1 or 2 , wherein the thickness of the ink for solid printing in the Kubelka-Munk equation is used as the parameter. Print color adjustment system according to any one of claims 1 to 3, which comprises using a gradation characteristic of said expected color as the parameter in the halftone of the command value. When changing the predicted color when the ink is overprinted, the thickness of the ink for solid printing in the Kubelka-Munk equation for obtaining the spectral reflectance of the ink to be overlaid on another ink is used as the parameter. print color adjustment system according to any one of claims 1 to 4, characterized in. The adjustment controller is before when adjusting the misregistration of Kishirushi Surimono, shifting the position of each of the plate of the ink of the printed material,
The printing according to any one of claims 1 to 5 , wherein the print control unit obtains a predicted value of the color of each dot of the printed matter in the overlap of the plates whose positions are shifted. Color adjustment system. The adjustment controller is print color adjustment system according to any one of claims 1 to 6, characterized in that to superimpose the noise on the predicted value of the image data. The color measurement process for measuring the color measurement value of each solid print of the ink used for the printed matter printed by the area modulation gradation and the density modulation gradation, and the color measurement process.
The color profile of the first printing machine that prints the printed matter using a print color prediction model that obtains the predicted value of the color of the printed matter printed from the command values of the area modulation gradation and the density modulation gradation from the color measurement value. And the process of generating
From the color profile, the predicted value of the color corresponding to the command value of each dot in the image data of the printed matter is obtained, the predicted value is used as the color information of the color of the printed matter, and the color information is used as the color profile of the second printing machine. And the process of converting to a control value and outputting to the second printing machine.
The process of comparing the color of the printed matter printed by the first printing press with the color of the printed matter printed by the second printing press and selecting the parameters to be adjusted in the printing color prediction model.
A process of changing the parameters in multiple stages, generating a plurality of the print color prediction models, and generating each of the color profiles corresponding to each of the print color prediction models.
A process of causing the second printing machine to print the image data according to each of the control values corresponding to the color information obtained from each of the color profiles .
The parameters used for the calculation of the prediction of the predicted color in the printing color prediction model are adjusted, and the plurality of the printing color prediction models are generated corresponding to the parameters adjusted in a plurality of stages to generate the plurality of the color profiles. look including a process to generate,
The print color prediction model uses the absorption coefficient and the scattering coefficient of each solid printing of the ink to predict the predicted value when the ink is overprinted, and determines the spectral reflectance at each dot of the printed matter. It includes a process obtained by Munk's formula, and uses the color value of the ink for solid printing in the Kubelka Munk's formula as the parameter.
Print color adjustment method characterized by and this.

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