JP6151673B2 - Print color prediction method and apparatus, profile generation method and apparatus, and program - Google Patents

Description

  The present invention relates to a printing color prediction method and apparatus, a profile generation method and apparatus, and a program, and more particularly to a technique for predicting color reproduction of a printed material with a protective film in which the printed material is coated with a protective film.

  It is known that the durability of an image and the quality of the printed surface are improved by coating a protective film on the image forming surface of the printed material (Patent Document 1). The term “image forming surface” is synonymous with “printing surface”. The color of the printed matter changes depending on whether the printing surface is covered with a protective film or not. There are various types of protective film, and when the combination of the type of protective film and the printed material (the result of combining paper, ink, and printing conditions) is enormous, the color of the printed material with protective film for all combinations Creating a reproduction profile is very time consuming. For this reason, operation of color management including a protective film is difficult.

  In order to solve this problem, there has been proposed a technique for estimating an optical property value of a protective film and easily predicting color reproduction of a printed material with a protective film (Patent Documents 1 and 2). Patent Document 1 proposes a method capable of reducing the number of work steps required for generating a profile without reducing the color reproduction accuracy of a printed matter with a protective film. According to Patent Document 1, the spectral reflectance of a printed material is acquired, the optical property value of the protective film is estimated, and the spectral reflectance of the printed material with the protective film is predicted using the acquired spectral reflectance and optical property value. It is the composition to do.

JP 2011-75304 A JP 2011-188091 A

  The technique described in Patent Document 1 predicts the color of a printed matter with a protective film by applying a Kubelka-Munk model. In the Kubelka-Munk model, the light intensity in the incident direction and the light intensity in the reflection direction are assumed under the assumption that an isotropic and homogeneous light scattering absorption layer spreads infinitely on a uniform substrate. And the relationship between light scattering and absorption are simplified and modeled in one dimension. The “base” is understood to be an element corresponding to the “printed material” in the present invention. Further, it is understood that the “light scattering / absorbing layer” is an element corresponding to the “protective film” in the present invention.

  For printed matter that expresses light and shade etc. by area gradation, the assumption of “uniform background” applies to the paper white area and solid printing area, but the halftone part reproduced with halftone dots is “uniform It will be different from the assumption (premise) of the Kubelka-Munk model, not the “base”.

  The inventor of the present application newly found out that there is an effect that the halftone dot gain is increased by covering the printed surface of the printed matter with a protective film as compared with that before the protective film is coated. The inventors of the present application have also found that the degree of the effect of increasing the dot gain varies depending on the type of the protective film. However, the color prediction method based on the conventional Kubelka-Munk model cannot take into account the effect of dot gain by covering the protective film, and the conventional technique performs color prediction for a protective film that has a large effect of increasing dot gain. We found a new problem that accuracy would be lowered.

  The present invention has been made in view of such circumstances, and solves the above-described problems and provides a print color prediction method and profile creation that can further improve the color prediction accuracy of a printed matter with a protective film, as compared to the prior art. It is an object to provide a method, an apparatus, and a program.

  In order to achieve the above object, the following invention mode is provided.

  A printing color prediction method according to a first aspect is a printing color prediction method for predicting color reproduction of a printed material with a protective film in which a printed material is coated with a protective film, the printed color having a printed surface on which the protective film is uncoated. Spectral reflectance acquisition process to acquire the spectral reflectance of the protective film uncovered area, optical physical property value estimation process to estimate the optical physical property value of the protective film, and spectral distribution of the observation light source of the printed matter with protective film Spectral distribution acquisition step, an interaction characteristic estimation step for estimating a color change characteristic due to the interaction between the protective print and the underlying printed material coated with the protective film, and a printed material acquired by the spectral reflectance acquisition step Spectral reflectance, optical physical property value of protective film estimated by optical property value estimation process, spectral distribution of observation light source acquired by spectral distribution acquisition process, and interaction color estimated by interaction characteristic estimation process A prediction step of predicting the colorimetric values of printed materials with protective film on the basis of the reduction characteristics, a print color predicting method comprising.

  “A protective film non-covering region of a printed material” means a region of a printed surface that is not covered with a protective film. The “estimating process” includes a process of calculating a value using a predetermined arithmetic expression, function, lookup table, or the like. The “process for estimating the optical property value of the protective film” includes a calculation process for obtaining the optical property value from a physical quantity such as an actual measurement value. The “process for estimating the color change characteristic due to the interaction” includes a process for obtaining data indicating the color change characteristic due to the interaction by calculation or the like.

  According to the first aspect, since the color prediction process is performed in consideration of the color change characteristic due to the interaction between the printed matter on the base and the protective film, the color prediction accuracy is improved as compared with the conventional color prediction method. Can do.

  As a second aspect, in the print color prediction method according to the first aspect, the color change characteristic due to the interaction may be a dot gain characteristic indicating a dot gain increase amount due to the interaction between the protective film and the underlying printed matter. it can.

  As a third aspect, in the printing color prediction method of the first aspect or the second aspect, the optical physical property value of the protective film is an independent two of the intrinsic reflectance, scattering coefficient, and absorption coefficient for each light wavelength of the protective film. It can be set as the structure containing one optical property value.

  As a fourth aspect, in the printing color prediction method according to any one of the first aspect to the third aspect, in the optical property value estimation step, spectral reflectances of at least two types of bases on which the protective film is uncoated are obtained. The first acquisition step, the second acquisition step of acquiring the spectral reflectance in the state where the protective film is disposed on each of at least two types of bases, and the first acquisition step and the second acquisition step, respectively. Using the obtained spectral reflectance and the optical property value of the protective film as an unknown, an arithmetic step for obtaining a relational expression based on a mathematical model for each of at least two kinds of backgrounds and solving the relational expressions for each background simultaneously , And the optical property value of the protective film can be estimated based on the calculation process of the calculation step.

  As a fifth aspect, in the printing color prediction method according to any one of the first aspect to the fourth aspect, the interaction characteristic estimation step protects each of a plurality of types of backgrounds composed of monochrome gradations having different dot area ratios. Based on the dot gain characteristics with the protective film with the film covered and the dot gain characteristics without the protective film with the protective film uncoated for each of the multiple types of bases, It can be configured to perform a process of estimating a color change characteristic due to a change in dot gain as an action.

  As a sixth aspect, in the printing color prediction method according to the fifth aspect, the interaction characteristic estimation step includes a dot gain amount of the primary color when there is a protective film and a dot gain amount of the primary color when there is no protective film. And a step of specifying the relationship between the dot area ratio of the base and the dot gain increase amount when there is no protective film.

  As a seventh aspect, in the printing color prediction method according to any one of the first aspect to the sixth aspect, the interaction characteristic estimation step includes a color due to the interaction between the printed matter of the base coated with the protective film and the protective film. A correction parameter acquisition step of acquiring a correction parameter for correcting data indicating the change characteristic and a correction processing step of correcting the color change characteristic using the correction parameter can be adopted.

  As an eighth aspect, in the print color prediction method according to the seventh aspect, the data indicating the color change characteristic due to the interaction is data indicating the dot gain increase amount characteristic of the primary color, and the correction parameter is a value more than the secondary color. It can be configured as a parameter indicating the suppression rate of the dot gain increase amount for the next color.

  As a ninth aspect, in the printing color prediction method according to any one of the first aspect to the eighth aspect, the prediction step is based on a mathematical model using the optical property value estimated by the optical property value estimation step, and is protected First processing step for performing processing for predicting spectral reflectance of printed matter with film, and spectral reflectance of printed matter with protective film predicted by first processing step or spectral of printed matter with protective film predicted by first processing step And a second processing step of correcting the color prediction value calculated based on the reflectance using the color change characteristic due to the interaction estimated by the interaction characteristic estimation step.

  The profile generation method according to the tenth aspect uses the print color prediction method according to any one of the first aspect to the ninth aspect to obtain a colorimetric value of the printed matter with a protective film from the spectral reflectance of the color chart as the printed matter. Further, a determination processing step for determining a colorimetric value corresponding to each grid point of the color conversion table based on the predicted colorimetric value of the printed matter with protective film, and a measurement process corresponding to each grid point of the color conversion table. And a generation processing step of generating a profile based on a color value.

  A printing color prediction apparatus according to an eleventh aspect is a printing color prediction apparatus that predicts color reproduction of a printed material with a protective film in which a printed material is coated with a protective film, the printed color predicting apparatus having a printed surface on which the protective film is uncoated. Spectral reflectance acquisition unit that acquires the spectral reflectance of the protective film non-covering area, optical property value estimation unit that performs processing to estimate the optical property value of the protective film, and spectral distribution of the observation light source of the printed matter with protective film A spectral distribution acquisition unit, an interaction characteristic estimation unit that performs a process of estimating a color change characteristic due to an interaction between the protective printed material and the underlying printed material that is coated with the protective film, and a printed material acquired by the spectral reflectance acquisition unit. Spectral reflectance, optical physical property value of protective film estimated by optical property value estimation unit, spectral distribution of observation light source acquired by spectral distribution acquisition unit, and color change due to interaction estimated by interaction characteristic estimation unit Based on characteristics A prediction unit that predicts the colorimetric values of printed materials with protective film Te is print color predicting apparatus comprising a.

  In the print color prediction apparatus of the eleventh aspect, the same matters as the specific matters of the print color prediction method specified in the second to ninth aspects can be appropriately combined. In that case, the process and the processing content specified in the printing color prediction method can be grasped as the elements of the processing unit and the functional unit corresponding thereto.

  A profile generation apparatus according to a twelfth aspect includes a print color prediction apparatus according to an eleventh aspect and a color conversion table based on a colorimetric value of a printed matter with a protective film predicted by a prediction unit from a spectral reflectance of a color chart as a printed matter. A profile generation apparatus includes a determination processing unit that determines a colorimetric value corresponding to each grid point, and a generation processing unit that generates a profile based on the colorimetric value corresponding to each grid point of the color conversion table.

  In the profile generation device of the twelfth aspect, the same matters as the specific matters of the print color prediction method specified in the second to ninth aspects can be appropriately combined. In that case, the process and the processing content specified in the printing color prediction method can be grasped as the elements of the processing unit and the functional unit corresponding thereto.

  A program according to a thirteenth aspect is a program for causing a computer to realize a function of predicting color reproduction of a printed material with a protective film in which the printed material is coated with a protective film, and has a printing surface on which the protective film is uncoated. Spectral reflectance acquisition function to acquire the spectral reflectance of the protective film non-covered area of the printed material, optical physical property value estimation function to estimate the optical physical property value of the protective film, and spectral distribution of the observation light source of the printed material with protective film Acquired by the spectral distribution acquisition function, the interaction characteristic estimation function that performs the process of estimating the color change characteristics due to the interaction between the protective printed material and the underlying printed matter that is coated with the protective film, and the spectral reflectance acquisition function. Spectral reflectance of printed material, optical property value of protective film estimated by optical property value estimation function, spectral distribution of observation light source acquired by spectral distribution acquisition function, and interaction property estimation function Is a program for implementing a prediction function, to a computer for predicting the estimated colorimetric values of printed materials with protective film based on the color change characteristics due to the interaction with Ri.

  Regarding the program of the thirteenth aspect, the same matters as the specific matters of the printing color prediction method specified in the second to ninth aspects can be appropriately combined. In that case, the process and process content specified in the print color prediction method can be grasped as an element of a “function” of a program that performs a process and an operation corresponding thereto.

  According to the present invention, it is possible to further improve the color prediction accuracy of a printed matter with a protective film as compared with the prior art.

FIG. 1 is a graph showing the relationship between the dot area ratio on the data and the real area ratio on the printed material. Figure 2 is a graph showing the relationship between the halftone dot area ratios and the amount of dot gain on the data. FIG. 3 is an explanatory diagram showing an outline of the printing color prediction method according to the present embodiment. FIG. 4 is a diagram showing a first example of a protective film color change characteristic grasp chart. FIG. 5 is a diagram showing a second example of the protective film color change characteristic grasp chart. FIG. 6 is a diagram showing a third example of the protective film color change characteristic grasp chart. FIG. 7 is a diagram showing a fourth example of the protective film color change characteristic grasp chart. FIG. 8 is a schematic cross-sectional view as an example of a measurement sample prepared for estimating the optical property value of the protective film. FIG. 9 is a schematic cross-sectional view as another example of a measurement sample prepared for estimating the optical property value of the protective film. FIG. 10 is a graph showing an example of a primary color dot gain increase amount characteristic of a glossy laminate. FIG. 11 is an explanatory perspective view showing an example of a printing system in which an image processing apparatus as a printing color prediction apparatus according to the present embodiment is incorporated. FIG. 12 shows an example of a color chart. FIG. 13 is a functional block diagram of the image processing apparatus. FIG. 14 is a flowchart showing the steps of the printing color prediction method according to this embodiment. FIG. 15 is a flowchart showing the contents of the optical property value estimating step. FIG. 16 is a flowchart showing the contents of the colorimetric value prediction step. FIG. 17 is a flowchart showing the contents of another example of the colorimetric value prediction process. FIG. 18 is a flowchart showing the steps of the profile generation method according to this embodiment. FIG. 19 is an explanatory diagram showing a first example of color conversion using a profile of a printed matter with a protective film created according to the present embodiment. FIG. 20 is an explanatory diagram illustrating a usage example 2 of color conversion using a profile of a printed matter with a protective film created according to the present embodiment. FIG. 21 is an explanatory diagram illustrating a usage example 3 of color conversion using a profile of a printed matter with a protective film created according to the present embodiment. FIG. 22 is an explanatory diagram showing a usage example 4 of color conversion using a profile of a printed matter with a protective film created according to the present embodiment. FIG. 23 is a flowchart of the color conversion method according to this embodiment. FIG. 24 is a flowchart showing an example of the color conversion method according to this embodiment. 25A to 25C are explanatory diagrams showing a gamut conversion process by black point correction. FIG. 26 is a diagram showing an example of an adjustment GUI (Graphical User Interface) screen for adjusting the color change characteristic parameter. FIG. 27 is a functional block diagram showing another configuration example of the image processing apparatus.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings.

[Increase in optical dot gain due to interaction between protective film and underlying printed matter]
First, the increase phenomenon of the optical dot gain due to the interaction between the protective film and the underlying printed matter found by the inventors will be described.

  In general, a printed matter expressed by area gradation has a larger halftone dot area ratio, and the light absorbed by the ink increases due to light scattering inside the paper (that is, the reflectance decreases), and the apparent halftone area A phenomenon called optical dot gain in which the dot area ratio increases is known. The inventor of the present application has found that a phenomenon in which the optical dot gain is further increased by covering the printed material with a protective film as compared with that before the protective film is coated.

The graph shown in FIG. 1 shows the halftone dot area ratio on the data for each of the printed material without protective film not coated with the protective film and the printed material with various protective films coated on the printed material, It is the example which plotted the relationship with the real area rate on printed matter. FIG. 1 shows an example of cyan gradation by flexographic printing.

The horizontal axis in FIG. 1 represents the dot area ratio on the image data (described as “data area ratio”), and the vertical axis represents the substantial dot area ratio on the print (“real area ratio on print”). Description). The actual area ratio on the printed material is an actual area ratio including a mechanical dot gain, which is a phenomenon in which a halftone dot region physically expands, and an optical dot gain.

  In FIG. 1, the printed matter without a protective film is described as “Normal”. In addition, FIG. 1 shows an example in which three types of glossy laminate, glossy varnish, and matte varnish are used as the protective film, and “Lami (Gloss)” and “Varnish (Gloss)” are shown respectively. "," Varnish (matte) ".

  The real area ratio on the printed material can be obtained from the Murray-Davies equation. Specifically, in a certain single color gradation, the colorimetric value of the area ratio 0% (paper white) is Xw, the colorimetric value of the area ratio 100% (solid) is Xs, and the area ratio on the data of the actual area ratio calculation target. When the colorimetric value of X is X, the actual area ratio with respect to the area ratio on the target data is represented by the following equation.

Real area ratio = {(Xw−X) / (Xw−Xs)} × 100
In the case of the cyan gradation, the actual area ratio was calculated using X among the XYZ values. However, since the change in the X value was the largest among the XYZ values in the cyan gradation, the effect of measurement error was affected. This is because it can be made smaller. It is desirable to calculate using the Y value for the magenta gradation, the Z value for the yellow gradation, and the Y value for the black gradation. Similarly, when applied to inks other than CMYK, it is desirable to calculate the real area ratio using an XYZ value having a large change.

  FIG. 2 calculates the dot gain amount (real area ratio on printed matter−data area ratio) based on the graph of FIG. 1, and the vertical axis is displayed as the dot gain amount (real area ratio−data area ratio). Is.

  As shown in FIG. 2, it can be seen that the dot gain amount is increased in all the printed materials after the coating of the protective film compared to the printed material without the protective film (normal). This is due to the interaction between the protective film and the printed material. Note that it is considered that the mechanical dot gain is hardly changed by the coating of the protective film, and the increase in the optical dot gain is presumed to be the dominant factor in increasing the dot gain shown in FIG. . It has been found that the dot gain is increased by covering the protective film as described above.

  However, in the color prediction model based on the Kubelka-Munk model described in Patent Document 1, an increase in dot gain due to the interaction between the protective film and the printed material is not considered. Therefore, the technique described in Patent Document 1 has a problem that the color prediction accuracy is low for a protective film that has a large effect of increasing dot gain due to interaction.

  The embodiment of the present invention provides a color prediction technique that takes into account the effect of an increase in dot gain due to the interaction between a protective film and a printed material.

  The color change due to the interaction between the protective film and the printed material is due to the influence of the solvent contained in the protective film (surface processing) adhesive and the heat during processing, in addition to the effect of increasing the dot gain. There may also be a phenomenon that the ink on the printed matter itself changes color. However, basically, the effect of “increasing dot gain” described here is considered to be dominant.

[Outline of Embodiment]
FIG. 3 is an explanatory diagram showing an outline of the printing color prediction method according to the present embodiment. In the print color prediction method of the present embodiment, in addition to using the optical property value of the protective film as the color change characteristic parameter of the protective film, the dot gain increase amount characteristic as the color change characteristic due to the interaction between the protective film and the printed material Is used.

  Therefore, in the printing color prediction method of the present embodiment, the protective film color change characteristic grasping chart 10 is created in order to acquire the color change characteristic parameter of the protective film. The protective film color change characteristic grasp chart 10 includes a black and white patch 14, a primary color gradation patch 16, and a multi-order color gradation patch 18 as a patch group 12 without a protective film. Further, the protective film color change characteristic grasp chart 10 includes a black and white patch 24, a primary color gradation patch 26, and a multi-order color gradation patch 28 as a patch group 22 with a protective film covered with the protective film 20.

  The term “with protective film” means a state in which the protective film is coated, and is synonymous with “with protective film” and “after protective film coating”. The term “without protective film” means a state in which the protective film is uncoated, and is synonymous with “unprotected film” and “before protective film coating”. These terms are not limited to the meaning of specifying the presence or absence of a protective film over the entire printed surface, but can be understood in the sense of specifying the presence or absence of a protective film for a part of the image area of interest on the printed surface. it can.

  The black and white patches 14 and 24 are patches for grasping light scattering and absorption characteristics, which are optical properties of the protective film 20.

  The primary color gradation patches 16 and 26 are patches for grasping the dot gain increase amount characteristic of the primary color. The primary color gradation patches 16 and 26 include patches of a plurality of gradations in which gradation values are changed in stages. The primary color gradation patches 16 and 26 can be, for example, K gradation patches in which the gradation of the primary color black (K) is changed in 10% increments from 0 to 100%. Further, the primary color gradation patches 16 and 26 have a range from 0 to 100% for each of the primary colors cyan (C), magenta (M), yellow (Y), and black (K). It is possible to obtain gradation patches for each color with gradations changed in% increments.

  The multi-order color gradation patches 18 and 28 are patches for grasping the dot gain increase amount suppression rate of multi-order colors. The multi-order color gradation patches 18 and 28 include patches of a plurality of gradations in which gradation values are changed stepwise for each of the secondary color, tertiary color, and quaternary color. The multi-order color gradation patches 18 and 28, for example, each of the secondary colors CM, MY, YC, the tertiary color CMY, and the quaternary color CMYK are in 20% increments with the balance of each color equivalent amount. A gradation patch with a different gradation can be obtained. However, it is preferable to exclude 0% and 100%.

  Although details will be described later, a configuration in which the dot gain increase amount characteristic of the primary color is also applied to the multi-color without using the dot gain increase suppression rate of the multi-color is possible. In that case, the multi-order color gradation patches 18 and 28 may be omitted.

  The protective film 20 can be made of laminate, varnish, transparent ink, clear toner, acrylic plate, or other various materials, or may be an appropriate combination thereof. A protective film color change characteristic grasp chart 10 is created for each type of protective film.

  The protective film color change characteristic grasping chart 10 is preferably formed as a single printed matter including the patch group 12 without the protective film and the patch group 22 with the protective film. The patch group in the color change characteristic grasp chart 10 may be formed separately on a plurality of sheets (print media). For example, the patch group 12 without a protective film and the patch group 22 with a protective film may be created as separate printed materials.

Next, colorimetry patch of the protective film color change characteristic grasping chart 10 (14～18,24～ 2 8) by the calorimeter 30. A spectrocolorimeter is used as the colorimeter 30. The spectrocolorimeter measures the reflectance in the wavelength range of visible light at a predetermined wavelength increment, calculates the XYZ value using the XYZ color matching function representing the human visual spectral sensitivity, and obtains the colorimetric value can do. The colorimeter 30 has, for example, a reflectance of a wavelength region of 380 nanometers [nm] -730 nanometers [nm] that is a visible light wavelength region with a wavelength step size (wavelength step) of 10 nanometers [nm]. taking measurement.

  A process of estimating the color change characteristic parameter of the protective film 20 is performed based on the colorimetric information of the patches (14 to 18) without the protective film and the patches (24 to 28) with the protective film. In FIG. 3, it is described as a block of “protective film color change characteristic parameter estimation process 40”. The color change characteristic parameters of the protective film 20 are classified into the following three types (a) to (c). That is, (a) the optical property value of the protective film, (b) the primary color dot gain increase characteristic due to the interaction between the protective film and the printed material, and (c) the multi-color dot gain increase suppression rate. Is done.

(A) Optical Physical Property Value of Protective Film The optical physical property value of the protective film includes an intrinsic reflectance representing the optical properties (light scattering and absorption), a scattering coefficient, and an absorption coefficient. However, since there is a relational expression among the three of the intrinsic reflectance, the scattering coefficient, and the absorption coefficient (see formula (9) described later), there are two independent parameters. The intrinsic reflectance is represented as “R∞”, the scattering coefficient as “Sx”, and the absorption coefficient as “Kx”. “S” is the scattering coefficient per unit thickness, and “x” is the thickness. Here, regarding the definition of the scattering coefficient, Sx (= S · x), which is the product of S and x, is defined as the scattering coefficient at the film thickness x (that is, one variable), but either S or Sx is used. May be. The definition of the absorption coefficient is the same, and the absorption coefficient K per unit thickness may be used, or Kx (= K · x), which is the product of K and x, is defined as the absorption coefficient at the film thickness x. May be.

  The intrinsic reflectance R∞, the scattering coefficient Sx, and the absorption coefficient Kx are parameters that depend on the wavelength. The intrinsic reflectance R∞ is synonymous with “spectral intrinsic reflectance R∞”.

  The optical property value of the protective film is estimated based on the respective colorimetric results of the monochrome patch 14 without the protective film and the monochrome patch 24 with the protective film. The process block for estimating the optical property value of the protective film is described as “optical property value estimation process 42 of the protective film” in FIG.

(B) Dot gain increase characteristic of the primary color due to the interaction between the protective film and the printed material The dot gain increase characteristic of the primary color due to the interaction between the protective film and the printed material may be a parameter Δdg common to all colors of CMYK. , CMYK may be set to parameters ΔCdg, ΔMdg, ΔYdg, and ΔKdg for each gradation. The dot gain increase amount characteristic of the primary color is a parameter depending on the actual area ratio of the base printed matter covered with the protective film. The dot gain increase amount characteristic of the primary color is acquired based on the respective colorimetric results of the primary color gradation patch 16 without the protective film and the primary color gradation patch 26 with the protective film. The block of the process for acquiring the dot gain increase amount characteristic of the primary color is described as “primary color dot gain increase characteristic acquisition process 44” in FIG.

(C) Multi-color dot gain increase suppression rate The multi-color dot gain increase suppression rate takes into account that the optical dot gain increase by the protective film is smaller for multi-order colors than for primary colors. It is a parameter. The dot gain increase amount suppression rate of the multi-order color serves as a correction parameter (correction coefficient) for correcting the parameter value in order to apply the dot gain increase amount parameter of the primary color to the multi-order color. For example, the secondary color correction parameter α, the tertiary color correction parameter β, and the quaternary color correction parameter γ can be determined.

  The dot gain increase amount suppression rate of the multi-order color is acquired based on the respective colorimetric results of the multi-order color gradation patch 18 without the protective film and the multi-order color gradation patch 28 with the protective film. The block of the process for acquiring the multi-color dot gain increase suppression rate is described as “multi-color dot gain increase suppression rate acquisition process 46” in FIG.

  Details of the estimation method of each parameter classified from the above (a) to (c) and the color prediction model using these parameters will be described later.

  As shown in FIG. 3, the protective film color change characteristic parameter estimation process 40 includes an optical property value estimation process 42 for the protective film, a dot gain increase characteristic acquisition process 44 for the primary color, and a multi-color dot. And gain increase amount suppression rate acquisition processing 46. However, the dot gain increase amount suppression rate of the multi-order color is positioned as a “correction parameter”, and a form in which the multi-color dot gain increase amount suppression rate acquisition process 46 is omitted is also possible.

  The color change characteristic parameter of the protective film is estimated to obtain parameters necessary for the calculation of color prediction, while the profile creation chart 50 without the protective film is output, and each patch of the profile creation chart 50 is assigned to the colorimeter 30. To measure the color. The profile creation chart 50 is a color chart used to create an ICC (International Color Consortium) profile. The printing surface of the profile creation chart 50 is not covered with a protective film. In the profile creation chart 50 without a protective film, the entire printed surface corresponds to the “protective film non-covering region”.

  By measuring the color of the profile creation chart 50 with the colorimeter 30, the spectral reflectance Rg (C, M, Y, K) of the printed matter without the protective film is obtained. In FIG. 3, “spectral reflectance Rg” is shown for simplicity.

  Change in color due to the optical characteristics of the protective film (here, light scattering characteristics and absorption characteristics) with respect to the spectral reflectance Rg (C, M, Y, K) of the print without protective film obtained by measuring the color of the profile creation chart 50 Processing for predicting the subsequent spectral reflectance Rkm (C, M, Y, K) is performed.

  That is, the Kubelka-Munk model 54 is applied to the spectral reflectance Rg (C, M, Y, K) of the printed material without the protective film, based on the optical property value (combination of R∞ and Sx) of the protective film. The spectral reflectance Rkm (C, M, Y, K) of the KM predicted value is obtained. In FIG. 3, “KM predicted value Rkm” is shown for simplicity. The notation “KM predicted value” means a value predicted from the Kubelka-Munk model 54.

  The Kubelka-Munk model 54 is a color prediction model that uses a function expression KM (Rg, R∞, Sx) known as the Kubelka-Munk expression described in Patent Document 1.

  Next, a colorimetric value calculation process 60 for obtaining XYZkm (C, M, Y, K) which is an XYZ value as a colorimetric value corresponding to the spectral reflectance Rkm (C, M, Y, K) of the KM predicted value. I do. In the colorimetric value calculation process 60, XYZkm (C, M, Y, K) corresponding to Rkm (C, M, Y, K) is obtained from the spectral distribution 62 of the observation light source and the XYZ color matching function 64. XYZkm (C, M, Y, K) corresponds to an XYZ value as a KM predicted colorimetric value. In FIG. 3, “KM predicted colorimetric value XYZkm” is described for simplicity.

  In the present embodiment, the dot gain increase model 70 that reflects the effect of the optical dot gain increase due to the interaction between the protective film and the printed matter is further applied to the KM predicted value, and the color predicted value of the printed matter with the protective film is applied. Is calculated. The dot gain increase model 70 is a color prediction model that obtains a color prediction value using at least the dot gain increase amount characteristic of the primary color.

  By the combination of the Kubelka-Munk model 54, the colorimetric value calculation process 60, and the dot gain increase model 70, the colorimetric value predicted value with the protective film is obtained from the colorimetric result of the profile creation chart 50 without the protective film. (Here, XYZ values) is obtained. A profile 74 conforming to the ICC profile format is generated based on the correspondence relationship between the predicted colorimetric value 72 of the printed matter with protective film and the CMYK value of each patch of the profile creation chart 50 obtained in this way.

The XYZ values can be converted into color coordinate values in a device-independent color space such as the L ^* a ^* b ^* color system by a known conversion formula.

In the present embodiment, an XYZ color system (stimulus value Y including luminance (brightness) and color stimulus values X and Z) is used as a color system (color coordinate system) of a device-independent color space representing colorimetric values. However, the color system is not limited to this example. Instead of the XYZ color system, the L ^* a ^* b ^* color system can be used. In addition to the Yxy color system (luminance Y, chromaticity coordinates x, y) and L ^* u ^* v ^* color system defined by the International Commission on Illumination, HSV color system (hue H (hue), saturation) S (saturation), brightness V (value) or B (brightness)), HLS color system (hue H (hue), saturation S (saturation), luminance L (luminance)), YCbCr color system (luminance Y, Color difference (Cb, Cr) can be used.

In this specification, in order to simplify the notation, the color space of the L ^* a ^* b ^* color system is denoted as “Lab color space”, and the chromaticity value represented by the coordinate value of the Lab color space is denoted as “Lab value”. ". In addition, image data in which the image signal value of each pixel is described by a Lab value may be referred to as a “Lab image”.

[Specific example of protective film color change characteristics grasp chart]
FIG. 4 is a first example of a protective film color change characteristic grasp chart. A protective film color change characteristic grasping chart 101 shown in FIG. 4 is a chart in which paper white and a K single-color gradation patch are combined, a patch group 22 with a protective film covered with a protective film 20, and no protective film. The protective film-less patch group 12 is provided. Note that the color and gradation of the patch are not sufficiently expressed in FIG. Reference numeral 16K in FIG. 4 indicates a K monochrome gradation patch without a protective film, and reference numeral 26K indicates a K monochrome gradation patch with a protective film. In the paper white area, any image position can be used as a white patch. The protective film color change characteristic grasping chart 101 shown in FIG. 4 is a chart that does not include the multi-order color gradation patches 18 and 28 described in FIG. The protective film color change characteristic grasping chart 101 shown in FIG. 4 includes the black and white patches 14 and 24 and the primary color gradation patches 16 and 26 described in FIG. It has a configuration.

  FIG. 5 is a second example of a protective film color change characteristic grasp chart. A protective film color change characteristic grasping chart 102 shown in FIG. 5 is a chart in which paper white and single color gradation patches of CMYK colors are combined, and a patch group 22 with a protective film covered with the protective film 20, and protection It has a patch group 12 without a protective film without a film. The protective film color change characteristic grasping chart 102 shown in FIG. 5 is a chart that does not have the multi-order color gradation patches 18 and 28 described in FIG. The protective film color change characteristic grasping chart 102 shown in FIG. 5 includes black and white patches 14 and 24 and primary color gradation patches 16 and 26 described in FIG. It has composition which has.

  Reference numeral 16C in FIG. 5 indicates a C single-color gradation patch without a protective film, reference numeral 16Y indicates a Y single-color gradation patch without a protective film, and reference numeral 16M indicates an M single-color gradation patch without a protective film. In FIG. 5, reference numeral 26C indicates a C single color gradation patch with a protective film, reference numeral 26Y indicates a Y single color gradation patch with a protective film, and reference numeral 26M indicates an M single color gradation patch with a protective film. .

  FIG. 6 is a third example of the protective film color change characteristic grasp chart. The protective film color change characteristic grasping chart 103 shown in FIG. 6 is a chart in which paper white, a K single-color gradation patch, and a multi-order color gradation patch are combined, and a patch with a protective film covered with the protective film 20. The group 22 and the protective film-free patch group 12 without the protective film are included. The multi-color gradation patches 18, 28 include a secondary color gradation patch, a tertiary color gradation patch, and a quaternary color gradation patch. The protective film color change characteristic grasping chart 103 shown in FIG. 6 includes all of the monochrome patches 14, 24, the primary color gradation patches 16, 26, and the multi-color gradation patches 18, 28 described in FIG. It is a configuration that includes.

  FIG. 7 is a fourth example of the protective film color change characteristic grasp chart. The protective film color change characteristic grasping chart 104 shown in FIG. 7 is a chart in which single-color gradation patches and multi-order color gradation patches of paper white and CMYK colors are combined, and the protective film covered with the protective film 20. It has a patch group 22 with protection and a patch group 12 without protection film without protection film. The multi-color gradation patches 18, 28 include a secondary color gradation patch, a tertiary color gradation patch, and a quaternary color gradation patch. The protective film color change characteristic grasping chart 104 shown in FIG. 7 includes all of the black and white patches 14 and 24, the primary color gradation patches 16 and 26, and the multi-order color gradation patches 18 and 28 described in FIG. It is a configuration that includes.

[Parameterization of color change characteristics of protective film]
Next, parameterization of the color change characteristics of the protective film will be described separately for each parameter type.

(A) Optical property values used in the Kubelka-Munk model
A technique for predicting the spectral reflectance of a printed matter with a protective film by applying the Kubelka-Munk model is described in Patent Document 1. In the Kubelka-Munk model, the spectral reflectance R of a printed matter with a protective film is predicted based on the following equation (1). Each variable is a function for each optical wavelength, but is omitted for convenience of explanation.

_{R = [(R g -R∞)} / R∞-R∞ (R g -1 / R∞) exp {Sx (1 / R∞-R∞)}] / [(R g -R∞) - ( R _g −1 / R∞) exp {Sx (1 / R∞−R∞)}] (1)
“R _g ” in the formula (1) represents the spectral reflectance of a single printed material without a protective film. “R∞” represents the intrinsic reflectance of the protective film. “S” represents the scattering coefficient per unit thickness of the protective film, and “x” represents the thickness of the protective film (“New Contribution to the Optics of Intensely Light-Scattering Materials. Part I ” , JOURNAL OF THE OPTICAL SOCIETY OF AMERICA, VOLUME38, NUMBER5, PP, 448-457, MAY, 1948).

R _g is data obtained from the measurement result of the profile creation chart 50 described in FIG.

  The intrinsic reflectance R∞, which is an optical property value of the protective film, and the scattering coefficient Sx are estimated based on the colorimetric result of the protective film color change characteristic grasp chart 10.

  FIG. 8 is a schematic cross-sectional view of a measurement sample 110 created to estimate the optical property value of the protective film 20. The measurement sample 110 is realized by a combination of the black-and-white patch 14 without the protective film and the black-and-white patch 24 with the protective film in the protective film color change characteristic grasp chart 10 described with reference to FIG.

The measurement sample 110 includes a base 112 having a spectral reflectance Rg ₁ made of a white opaque body, a black material 114, and a protective film 20. The substrate 112 corresponds to a sheet as a print medium. The black material 114 corresponds to K ink. A region where the black material 114 is attached on the substrate 112 corresponds to a black patch. In addition, a region where the black material 114 does not adhere to the base material 112 is a so-called white paper region and corresponds to a “white patch”.

  In FIG. 8, among the areas where the black material 114 is adhered, the area where the protective film 20 is further laminated on the black material 114 corresponds to a black patch with a protective film, and is protected on the black material 114. A region where the film 20 is not covered corresponds to a black patch without a protective film.

  In FIG. 8, among the paper white areas where the black material 114 is not attached, the area where the protective film 20 is laminated on the base material 112 corresponds to the white patch with the protective film. A region where the protective film 20 is not covered corresponds to a white patch without a protective film.

  The process of acquiring the spectral reflectance from each of the black and white patches 14 without the protective film corresponds to one form of the “first acquisition process”. Further, the process of acquiring the spectral reflectance from the black and white patch 24 with the protective film corresponds to one form of the “second acquisition process”.

An operator measures the spectral reflectance of each part of the measurement sample 110 using the colorimeter 30 (see FIG. 1). As a result, the spectral reflectance obtained from the region where the protective film 20 is coated on the base material 112 (white patch with protective film) is R ₁ , and the region where the black material 114 is provided on the base material 112 (black patch without protective film) ) Is the spectral reflectance obtained from Rg ₂ , and the spectral reflectance obtained from the region where the protective film 20 is further coated on the base material 112 via the black material 114 (black patch with protective film) is R ₂ (R ₁ > Assume that a measured value of R ₂ ) is obtained.

  From these measured values, arithmetic processing for obtaining optical property values is performed according to the following equations (2) to (4).

The intrinsic reflectance R∞ of the protective film 20 is calculated by mathematical analysis.
R∞ = {C− (C ² −4) ^1/2 } / 2 (2)
C = {(R ₁ + Rg ₂ ) (R ₂ · Rg ₁ -1)-(R ₂ + Rg ₁ ) (R ₁ · Rg ₂ -1)} / (R ₂ · Rg ₁ -R ₁ · Rg ₂ ) ... (3)
(Refer to “Special Articles on Paper: Takaga Paper, But Paper, Again Paper”, “Paper Characteristics, Evaluation Methods, and Trends in Standards” (2004, Journal of the Imaging Society of Japan 150)). When R ₁ <R ₂ , the subscripts 1 and 2 in formula (3) are reversed.

  Here, the intrinsic reflectance R∞ is a reflectance when it is assumed that the sample has an infinite thickness. Therefore, in the case where a large number of the same type of protective film 20 can be formed, the intrinsic reflectance R∞ may be directly measured.

Next, using the measured value R _n (n = 1 or 2), the measured value Rg _n (n = 1 or 2), and R∞ calculated by the equation (2), the scattering coefficient S of the protective film 20 and The product of the thickness x can be calculated as the following formula (4) (see formula (21) on page 88 of Yoichi Miyake et al. “Fundamentals and application techniques of color reproduction” (publisher: Triqueps Co., Ltd.)) .

S · x = ln [{( R∞-Rg n) (1 / R∞-R n)} / {(R∞-R n) (1 / R∞-Rg n)}] / (1 / R∞ -R∞) (4)
In Expression (4), “S” is a scattering coefficient per unit thickness, and “x” is the thickness of the protective film 20.

  As described above, the intrinsic reflectance R∞ and the scattering coefficient Sx, which are optical properties of the protective film 20, can be estimated using the measurement sample 110 in which the base material 112, the black material 114, and the protective film 20 are combined.

  Note that the measurement sample 110 is not limited to the example of FIG. 8, and as shown in FIG. 9, a white base 116w and a black base 116b are arranged side by side, and a protective film is provided so as to straddle both bases 116w and 116b. 20 may be laminated.

  As described with reference to FIG. 8 and FIG. 9, the optical property values (the intrinsic reflectance R∞ and the scattering coefficient Sx) of the protective film 20 are estimated using the measurement sample 110 in which two types of bases and the protective film 20 are combined. can do. In the example of FIG. 8, the two types of bases can be understood as the surface of the base material 112 as one type of base and the surface of the black material 114 as another type of base. In the example of FIG. 9, it can be understood that the ground 116w is one type of ground and the ground 116b is another type of ground. In the example of FIGS. 3 to 7, it is possible to grasp the white patch of paper white as one type of background and the black patch of solid K as another type of background.

  However, when a different ground from the two kinds of ground is used, there is a possibility that this optical property value cannot be applied as it is due to the influence of the difference in surface physical properties. In other words, depending on the combination of the protective film 20 and another base, there is a difference in the optical physical property value, and it is also assumed that the color reproduction accuracy is lowered.

  Therefore, not only the two types necessary for estimation at least, but also a measurement sample in which n (n> 2) types of bases and the protective film 20 are combined, the optical physical property value (inherent reflectance R) of the protective film 20 is used. More preferably, ∞ and scattering coefficient Sx) are estimated.

Specifically, to prepare for different n types of underlying spectral reflectance Rg _n, the measurement by coating the same type of the protective film 20 samples (not shown). For example, K primary color gradation patches can be used as different n types of bases.

Then, the spectral reflectance Rg _n before and after the protective film coating by measuring the measurement sample, after obtaining the R _n, according to equation (1), the two unknowns inherent reflectivity R∞ and scattering coefficients Sx Establish a nonlinear equation. Here, since one relational expression is formed for one type of base, a total of n simultaneous equations are established for n types of bases.

  The number of unknowns is two with respect to the number of simultaneous equations (n), which is redundant. Here, it is possible to estimate an unknown that best satisfies the relationship between the equations. Here, not only the case where the solution of the simultaneous equations is uniquely determined as in the case described above, but also the estimation of the optimum unknown based on a predetermined evaluation function is included in “solving the simultaneous equations”.

For example, the right side of the KM of the formula (1) (Rg _i, R- [infinity], Sx) when the, equation (5) as an evaluation function provided,
Err = Σ {R _i −KM (Rg _i , R∞, Sx)} ² (5)
The estimated value can be (R∞, Sx) that minimizes the value of Err in equation (5).
Note that “Σ” represents the sum of i = 1,..., N.

  In order to obtain the estimated value of (R∞, Sx), a known nonlinear optimization method such as the steepest descent method, Newton method, quasi-Newton method, or simplex method can be used.

  As described above, when n types of bases are used, it is possible to reduce estimation variations (estimation errors) of the intrinsic reflectance R∞ and the scattering coefficient Sx due to the influence of differences in the surface physical properties of the bases.

Note that the Kubelka-Munk model may be applied after correcting the measured spectral reflectance R _n using Saunderson's correction formula (“Calculation of the color pigment plastics”, JOURNAL OF THE OPTICAL SOCIETY). OF AMERICA, VOLUME32, PP, 727-736, 1942).

Specifically, as shown in the following equations (6) and (7), the influence of light reflection generated at the interface between the protective film 20 and the outside is excluded instead of the actually measured spectral reflectance R _i ′. spectral reflectance R _i that can be used. Here, r ₁ is the spectral reflectance of the incident light from the outside to the protective film 20 at the interface with the protective film 20, and r ₂ is the interface of the outgoing light from the protective film 20 to the outside with the protective film 20. Is the spectral reflectance at.

R _i ′ = r ₁ + (1−r ₁ ) (1−r ₂ ) R _i / (1−r ₂ R _i ) = SD (R _i , r ₁ , r ₂ ) (6)
R _i = (R _i ′ −r ₁ ) / {(1−r ₁ ) (1−r ₂ ) + r ₂ R _i ′ −r ₁ r ₂ } = invSD (R _i ′, r ₁ , r ₂ )... (7)
At this time, the evaluation function Err ′ is given by the following equation (8), similarly to the equation (5).

Err ′ = Σ {invSD (R _i ′, r ₁ , r ₂ ) −KM (Rg _i ′, R∞, Sx)} ² (8)
If the spectral reflectances r ₁ and r ₂ are known numbers, they can be directly substituted into equation (8). Further, if the spectral reflectances r ₁ and r ₂ are unknowns, they can be estimated in the same manner as other unknowns (R∞, Sx). That is, it is possible to estimate (R∞, Sx, r ₁ , r ₂ ) that minimizes the value of Err ′ in Expression (8).

  By this correction, light reflection at the interface between the protective film 20 and the outside is further taken into consideration, so that the spectral reflectance of the printed matter with the protective film can be predicted with higher accuracy. Further, among the intrinsic reflectance R∞, the scattering coefficient S, and the absorption coefficient K, there is a relationship shown in the equation (9).

K / S = (1-R∞) ² / 2R∞ (9)
Therefore, the absorption coefficient K (or Kx) may be used instead of the intrinsic reflectance R∞ or the scattering coefficient S (or Sx). If any two of the three optical property values of intrinsic reflectance R∞, scattering coefficient S (or Sx), and absorption coefficient K (or Kx) are determined, the other value is uniquely determined. It is.

  The method for estimating the optical property value of the protective film is not limited to the method for solving the simultaneous equations described above, and a Monte Carlo method, a neutral network, a boosting algorithm, a genetic algorithm, or the like may be applied.

(B) Dot gain increase amount characteristic (Δdg) The dot gain increase amount characteristic (Δdg) is parameterized by obtaining the difference in the dot gain amount of the primary color gradation patch. That is, for each gradation patch, the dot gain amount before covering the protective film and the dot gain amount after covering the protective film are calculated based on the Murray-Davies equation. The difference between the calculated dot gain amounts (dot gain after coating the protective film−dot gain before coating the protective film) is the dot gain increase amount Δdg in the real area ratio before coating the protective film, and the look of the real area ratio before coating the protective film It is defined as a look-up table (LUT) or function. Δdg may be parameterized by representing the dot gain increase amount of the K gradation, or may be parameterized by averaging the dot gain amounts of the CMYK color gradations. Alternatively, the dot gain increase amount may be parameterized for each ink, and parameterized as dot gain increase amount ΔCdg for cyan, dot gain increase amount ΔMdg for magenta, dot gain increase amount ΔYdg for yellow, and dot gain increase amount ΔKdg for black. .

  The graph shown in FIG. 10 is an example of the primary color dot gain increase amount characteristic of the gloss-based laminate. The horizontal axis in FIG. 10 represents the real area ratio without a protective film (unit: “%”), and the vertical axis represents the dot gain increase amount Δdg.

  The dot gain increase amount characteristic of the primary color may be referred to as “primary color dot gain increase amount characteristic” or simply “dot gain increase amount characteristic”.

(C) Regarding the suppression rate of the multi-order color dot gain increase amount The suppression rate of the multi-order color dot gain increase amount is such that the difference between the measured value of the multi-order color patch and the predicted value based on the color prediction model described later is minimized. Optimize and decide. That is, the predicted colorimetric value after coating of the protective film predicted by the protective film color prediction model described later for the spectral reflectance of the multi-color patch without protective film in the protective film color change characteristic grasp chart, and the protective film color change characteristic It is determined so that the difference (color difference) from the measured colorimetric value of the multi-color patch with the protective film of the grasping chart is minimized. The suppression rate of the multi-color dot gain increase amount may be referred to as “multi-order color dot gain increase suppression rate” or simply “suppression rate”.

  The dot gain increase suppression rate of the secondary color is expressed as α, the dot gain increase suppression rate of the tertiary color is expressed as β, and the dot gain increase suppression rate of the quaternary color is expressed as γ. Since the amount of increase in optical dot gain decreases as the number of overlapping colors increases, the relationship is generally “1> α> β> γ> 0”. In addition, a form that does not use the multi-order color dot gain increase rate suppression rate is also possible.

  As another embodiment regarding the multi-color dot gain increase amount suppression rate, the suppression rate parameter may be defined as a parameter depending on the sum of the real area ratios of the CMYK colors before the protective film is coated. In that case, the suppression rate is defined as a function or a look-up table with respect to the sum of the real area rates before covering the protective film. Assuming that the total substantial area ratio before covering the protective film is Tef, the inhibition ratio parameter α can be expressed as α (Tef) as a function of Tef.

  As yet another embodiment relating to the multi-order color dot gain increase amount suppression rate, it is conceivable to optimize the suppression rate parameter according to the image. An exhaustive patch (for example, the same as the profile creation chart) is prepared in advance as the multi-order color patch, and the measured data of the color change by the protective film of the multi-order color is acquired comprehensively. Next, the image data to be color-converted is analyzed, and multi-order color patches corresponding to frequently appearing colors in the image are extracted from comprehensive multi-order color patches. Based on the extracted multi-order color patch, the suppression rate parameter is optimized, and a protective material-attached printed matter profile dedicated to the target image is created and used for color conversion.

[Color prediction model for printed matter with protective film]
Spectral reflectance after color change due to light scattering / absorption characteristics of protective film with respect to spectral reflectance Rg (C, M, Y, K) with respect to halftone dot area ratio (C, M, Y, K) on data before protective film coating The reflectance Rkm (C, M, Y, K) is obtained from the functional expression KM (Rg, R∞, Sx) of the Kubelka-Munk model.

Rkm (C, M, Y, K) = KM (Rg (C, M, Y, K), R∞, Sx)
The functional expression KM (Rg, R∞, Sx) of the Kubelka-Munk model may be expressed as “KM expression”. The KM formula is as described in the formula (1).

  Next, an XYZ value corresponding to Rkm (C, M, Y, K) (denoted as “XYZkm (C, M, Y, K)”) is obtained from the spectral distribution of the light source and the XYZ color matching function. This is applied to each patch of the profile creation chart 50 before covering the protective film to obtain the XYZ values of the entire chart, and a CMYK → XYZkm LUT is created by a lookup table (LUT) creation technique. The LUT that defines the correspondence relationship “CMYK → XYZkm” is hereinafter referred to as “XYZkm (C, M, Y, K)”. As the LUT creation technique, for example, the technique disclosed in Japanese Patent Laid-Open No. 2003-289446 and Japanese Patent Laid-Open No. 2006-24971 can be used.

  Next, the effect of increasing the optical dot gain is applied. If the real area ratio before covering the protective film with respect to the dot area ratio (C, M, Y, K) on the data is (Cef, Mef, Yef, Kef), the primary color, the secondary color, the tertiary color, and the quaternary color In the following manner, XYZ values that are color predicted values after surface processing of the printed matter (that is, after coating of the protective film) are obtained.

  The primary color (in the case of C) can be obtained by XYZ = XYZkm (C + Δdg (Cef), 0, 0, 0). The same applies to the other primary colors M, Y, and K, and description thereof is omitted.

  The secondary color (in the case of CM) can be obtained by XYZ = XYZkm (C + αΔdg (Cef), M + αΔdg (Mef), 0, 0). The same applies to the other secondary colors CY, MY, CK, MK, and YK, and description thereof is omitted.

  The tertiary color (in the case of CMY) can be obtained by XYZ = XYZkm (C + βΔdg (Cef), M + βΔdg (Mef), Y + βΔdg (Yef), 0). The same applies to the other tertiary colors CMK, MYK, and CYK, and description thereof is omitted.

  The quaternary color (CMYK) can be obtained by XYZ = XYZkm (C + γΔdg (Cef), M + γΔdg (Mef), Y + γΔdg (Yef), K + γΔdg (Kef)).

  Note that α, β, and γ are preferably included as the best mode, but are not essential. When the multi-order color dot gain increase rate suppression rate is not considered, it is handled as α = β = γ = 1. That is, the dot gain increase amount of the primary color is also applied to multi-order colors of the secondary color or higher.

  According to the above-described procedure, the color prediction value of the printed matter after coating with a protective film for any CMYK can be obtained.

  As another embodiment relating to the color prediction processing of the printed matter after coating the protective film, when the dot gain increase amount characteristic is parameterized for each ink (for each color of CMYK), the primary color, secondary color, tertiary color, and fourth For each next color, a color prediction value is obtained in the following manner.

  The primary color can be obtained by XYZ = XYZkm (C + ΔCdg (Cef), 0, 0, 0).

  The secondary color can be obtained by XYZ = XYZkm (C + αΔCdg (Cef), M + αΔMdg (Mef), 0, 0).

  The tertiary color can be obtained by XYZ = XYZkm (C + βΔCdg (Cef), M + βΔMdg (Mef), Y + βΔYdg (Yef), 0).

  The quaternary color can be obtained by XYZ = XYZkm (C + γΔCdg (Cef), M + γΔMdg (Mef), Y + γΔYdg (Yef), K + γΔKdg (Kef)).

  As yet another embodiment relating to the color prediction processing of the printed matter after coating the protective film, when the suppression rate is a parameter α (Tef) that depends on the sum of the real area ratios, the sum of the real area ratios Tef = Cef + Mef + Yef + Kef For each of the color, secondary color, tertiary color, and quaternary color, a color prediction value is obtained in the following manner.

  The primary color can be obtained as XYZ = XYZkm (C + Δdg (Cef), 0, 0, 0).

  The secondary color can be obtained as XYZ = XYZkm (C + α (Tef) Δdg (Cef), M + α (Tef) Δdg (Mef), 0, 0).

  The tertiary color can be obtained as XYZ = XYZkm (C + α (Tef) Δdg (Cef), M + α (Tef) Δdg (Mef), Y + α (Tef) Δdg (Yef), 0).

The quaternary colors are XYZ = XYZkm (C + α (Tef) Δdg (Cef), M + α (Tef) Δdg (Mef), Y + α (Tef) Δdg (Yef), K + α (Tef) Δdg (Kef))
Can be obtained as

  The multi-order color dot gain increase rate suppression rate corresponds to a correction parameter for correcting the primary color dot gain increase amount data. The process of acquiring the multi-color dot gain increase suppression rate corresponds to one form of the “correction parameter acquisition process”, and corrects the primary color dot gain increase data using the multi-color dot gain increase suppression rate. The processing step corresponds to one form of a “correction processing step”.

[Configurations with different numbers of colors]
The color prediction model according to the present embodiment is not limited to four CMYK colors, and can be similarly extended to the number of colors smaller than four colors or the number of colors larger than four colors. In addition, when the original color prediction target is 4-color printing, and then colors are added and the color prediction target is printing of 5 colors or more, without newly parameterizing the dot gain suppression rate of the fifth or higher color, All quaternary colors or more may be dealt with by applying quaternary color parameters.

[About arbitrary color space]
The colorimetric values are XYZ, but values of other color spaces such as Lab may be used. The color space for expressing the colorimetric values is not limited to the XYZ space, and any device-independent color space can be used.

[Extension to wavelength-dependent (spectral) dot gain increase characteristics]
In the above description, the dot gain increase characteristic has been described as a form independent of the wavelength, but may be modeled as a spectral dot gain increase characteristic. In other words, the Murray-Dav ies equation is spectrally expressed as a spectral real area ratio, and the spectral reflectance at an area ratio of 0% (paper white) is Rw (λ) and the area ratio is 100% in a certain monochromatic gradation. When the spectral reflectance of (solid) is Rs (λ) and the colorimetric value of the area ratio on the data subject to calculation of the real area ratio is R (λ), the spectral real area ratio (λ) relative to the area ratio on the target data. Is as follows.

Spectral real area ratio (λ) = {(Rw (λ) −R (λ)) / (Rw (λ) −Rs (λ))} × 100 (10)
The spectral dot gain amount (spectral real area ratio (λ) −area ratio on data) is calculated from the spectral real area ratio (λ) of equation (10), and the spectral dot gain increase characteristic Δdg (λ) is calculated from the spectral dot gain quantity. Can be calculated. If the spectral real area ratio before covering the protective film with respect to the halftone dot area ratio (C, M, Y, K) in the data is (Cef (λ), Mef (λ), Yef (λ), Kef (λ)) For each of the color, secondary color, tertiary color, and quaternary color, the color prediction value can be obtained in the following manner.

  The primary color (in the case of C) can be obtained as R = Rkm (C + Δdg (Cef (λ), λ), 0, 0, 0). The same applies to the other primary colors M, Y, and K, and description thereof is omitted.

  The secondary color (in the case of CM) can be obtained as R = Rkm (C + αΔdg (Cef (λ), λ), M + αΔdg (Mef (λ), λ), 0, 0)). The same applies to the other secondary colors CY, MY, CK, MK, and YK, and description thereof is omitted.

  The tertiary color (in the case of CMY) can be obtained as R = Rkm (C + βΔdg (Cef (λ), λ), M + βΔdg (Mef (λ), λ), Y + βΔdg (Yef (λ), λ), 0)). . The same applies to the other tertiary colors CMK, MYK, and CYK, and description thereof is omitted.

  The quaternary colors (CMYK) are R = Rkm (C + γΔdg (Cef (λ), λ), M + γΔdg (Mef (λ), λ), Y + γΔdg (Yef (λ), λ), K + γΔdg (Kef (λ), λ) )). For Rkm, a lookup table may be created for each wavelength.

  In the schematic diagram of the embodiment shown in FIG. 3, the KM predicted spectral reflectance (Rkm) is obtained from the spectral reflectance R of the print without protective film by applying the Kubelka-Munk model 54, and further the KM predicted colorimetric value (XYZ). Or Lab), and then the dot gain increase model 70 is applied to obtain the predicted colorimetric value (XYZ or Lab) with a protective film. However, the spectral dot gain increase amount characteristic is used. In this case, the Kubelka-Munk model 54 is applied from the spectral reflectance R without the protective film to obtain the KM predicted spectral reflectance (Rkm), and the “spectral dot gain increase model” is calculated with respect to the KM predicted spectral reflectance (Rkm). ”Is applied to calculate the predicted spectral reflectance of the printed matter with a protective film, and the colorimetric value is calculated by applying the spectral distribution 62 of the light source and the XYZ color matching function 64 to the obtained predicted spectral reflectance of the printed matter with the protective film. , With protective film Get things predicted colorimetric values (XYZ / Lab), the flow of. That is, the order of the application process of the colorimetric value calculation process 60 and the dot gain increase model 70 shown in FIG. 3 is changed.

[Example of color prediction accuracy evaluation]
Table 1 shows a comparison of the prior art and the embodiment of the present invention regarding the accuracy of color prediction of a printed matter with a protective film. In the experiment, the difference between the measured value and the predicted value of each colorimetric value when the four types of protective films were coated on the target base printed matter was evaluated.

  The ground print was printed by a combination of UV flexographic printing using UV curable UV (Ultra Violet ray) ink, coated paper, and CMYK four colors. The average color difference of about 1000 patches was evaluated for the measured values and predicted values of the colorimetric values when the four types of protective films shown in Table 1 were coated on the base printed matter. The numerical values shown in Table 1 are the average color differences.

  KM in the table is an abbreviation for “Kubelka-Munk”. As the parameters of optical property values used in the KM formula, values estimated from two types of black and white backgrounds were used. The dot gain increase amount characteristic Δdg of the primary color applied to the dot gain increase model was estimated from the K monochrome gradation patch.

  A comparative example is color prediction using the KM model of the prior art described in Patent Document 1.

Example 1 is color prediction that combines a KM model and a dot gain increase model. In Example 1, in the dot gain increase model, only the dot gain increase amount characteristic of the primary color is considered without using the dot gain increase suppression rate of the multi-color.

  Example 2 is color prediction that combines the KM model and the dot increase model, and considers the dot gain increase suppression rate of multi-order colors.

  For all the types of protective films evaluated in Table 1, the color prediction accuracy is improved and the average color difference is about “2” with respect to the KM model of the prior art. The color can be predicted with practical accuracy.

[Create profile]
By applying the above color prediction model to the patch of the profile creation chart 50 before covering the protective film, the chart colorimetric value after covering the protective film can be predicted. A profile of the printed matter with the protective film is created based on the chart colorimetric value (predicted value) after the protective film is coated.

[Print system configuration example]
FIG. 11 is an explanatory perspective view illustrating an example of a printing system in which an image processing apparatus as a printing color prediction apparatus and a profile generation apparatus according to the present embodiment is incorporated. The printing system 210 includes an editing device 214, an image processing device 216 as a printing color prediction device, a printing machine 218, a lamination processing device 220, and a colorimeter 30. The editing device 214 and the image processing device 216 are connected to each other via a communication network 212. The communication network 212 may be a local area network (LAN), a wide area network (WAN), or a combination thereof. The communication network 212 is not limited to a wired communication line, and part or all of the communication network 212 can be a wireless communication line. Further, in this specification, the notation of “connection” between devices capable of passing signals includes not only wired connection but also wireless connection.

  The editing device 214 is a device that generates an electronic document indicating the contents of an image to be printed. The editing device 214 is used to edit various types of image parts such as characters, graphics, patterns, and photographic images, and to perform a layout operation on a printing surface for each page. The editing device 214 has a function of editing and reviewing an electronic manuscript in addition to a function of creating an electronic manuscript. For example, document data described in a page description language (PDL) is used as an electronic document for printing. The editing device 214 generates an electronic document in a page description language (hereinafter referred to as PDL), for example, 8-bit image data including color channels of four colors (CMYK) and three colors (RGB). PDL is a language that describes image information such as text, graphics, and other format information, position information, and color information (including density information) within a “page” that is an output unit for printing and display. For example, PDF (which is an abbreviation for Portable Document Format and defined in ISO 32000-1: 2008), Postscript (registered trademark) of Adobe Systems, XPS (XML Paper Specification), and the like are known.

  A color scanner (not shown) is connected to the editing device 214. The color scanner can acquire color image data that is a component of an electronic document by optically reading a color document set at a predetermined position.

  The image processing device 216 performs various image processing on the electronic document in the PDL data format, converts the image into a print signal suitable for the printing method of the printing machine 218, and transmits the printing signal to the printing machine 218. Have The contents of the image processing performed by the image processing apparatus 216 include RIP processing for expanding an electronic document into a bitmap format (a type of raster image), color conversion processing, image enlargement / reduction processing, arrangement processing, and the like.

  The image processing device 216 is configured by a combination of computer hardware and software. The term software is synonymous with “program” or “application”. The image processing device 216 includes a main body 224, a display device 226, and an input device 228. Although a detailed configuration of the main body 224 is not illustrated, the main body 224 includes computer components such as a central processing unit (CPU), a memory, and a communication interface. The display device 226 is a color display that displays a color image. Although the keyboard 230 and the mouse 232 are provided as the input device 228, various input means such as a touch panel and a trackball can be employed instead of or in combination with these.

  The image processing apparatus 216 includes a media interface that can be connected to a portable memory 234 as an external storage medium on which electronic data can be recorded and erased. Further, a colorimeter 30 is connected to the image processing device 216.

  The function of the image processing device 216 and the function of the editing device 214 can be realized by a single computer. Alternatively, the function of the image processing device 216 can be realized by a plurality of computers. is there.

  Furthermore, a database DB can be connected to the communication network 212. Various data used by the image processing device 216 and the editing device 214 can be stored in the database DB. The database DB is one or a plurality of types of data exemplified by electronic manuscript job tickets, color sample data, target profiles, profiles suitable for media types, spectral distribution data of various light sources assumed as observation light sources, etc. It is a database server that manages data. As the job ticket, for example, a JDF (Job Definition Format) file can be used. The function of the database DB can be built in a storage unit inside the image processing apparatus 216.

  A printing machine 218 shown in FIG. 11 is an ink jet printing apparatus that forms a color image using standard inks of cyan (C), magenta (M), yellow (Y), and black (K). . The printing machine 218 is configured to form a color image by combining optional inks such as light cyan (LC), light magenta (LM), and other light colors, white (W), and transparent (CL) in addition to CMYK standard inks. be able to.

  The printing machine 218 prints a color image on a medium 236 serving as a printing medium by performing ejection control of each color ink based on a print signal received from the image processing apparatus 216, thereby forming a printed material 238. Note that the roll-shaped medium 236 shown in FIG. 11 is an unprinted medium 236 before being set in the printing machine 218. The term “printed material” includes various color charts 238 c such as the protective film color change characteristic grasp chart 10 and the profile creation chart 50 described in FIG. 1 in addition to the printed material printed based on the electronic document.

The laminating apparatus 220 is an apparatus that forms the protective film 20 on the printing surface of the printed matter 238. The laminating apparatus 220 performs heating and pressure processing using a heating roller (not shown) with the protective film 20 applied on the printed surface of the printed matter 238 and, if necessary, on the back surface thereof. Accordingly, the printing surface of the printed matter 2 38 forms a protective-film-covered print 242 covered with the protective film 20.

  For the base material of the media 236, various materials such as paper such as synthetic paper, cardboard, or aluminum vapor-deposited paper, resin such as vinyl chloride or polyethylene terephthalate (PET), or tarpaulin may be used. it can. For convenience of explanation, the medium 236 may be referred to as “paper”. Various materials such as a laminate film, a liquid, a varnish, a transparent ink, a clear toner, and a protective plate such as an acrylic plate can be used for the protective film 20.

The colorimeter 30 measures the colorimetric value of the measurement object. The colorimetric values are not only tristimulus values XYZ, uniform color space coordinate values L ^* a ^* b ^*, etc., but also distributions of optical property values with respect to wavelengths (hereinafter referred to as “spectral data”), for example, spectral radiation. Distribution (spectral distribution), spectral sensitivity distribution, spectral reflectance, or spectral transmittance is included.

  The printed matter 242 with the protective film thus obtained is posted at a predetermined place under a light source DS (not shown) as an observation light source.

[About the press]
In FIG. 11, an ink jet printer is illustrated as the printer 218, but the type of the printer is not particularly limited when the invention is implemented. Instead of the ink jet printer, various printing machines such as an electrophotographic printer, a laser printer, an offset printing machine, a flexographic printing machine, etc. can be adopted. It is also possible to construct a printing system including a plurality of printers by combining a plurality of types of printers. The term “printing machine” is understood to be synonymous with terms such as a printer, a printing apparatus, an image recording apparatus, an image forming apparatus, or an image output apparatus. As the color material, ink, toner, or the like can be used depending on the type of printing press.

[Example of color chart]
FIG. 12 is a diagram illustrating an example of the color chart 238c. A color chart 238c shown in FIG. 12 can be used as the profile creation chart 50 described in FIG. The color chart 238c in FIG. 12 identifies a plurality of (for example, 100) color patches 244, a numeric string 246 and an alphabetic character string 248 that specify the arrangement position of the color patches 244, and printing conditions of the color chart 238c. Print information 250. The plurality of color patches 244 have substantially the same shape (here, a square is illustrated), and those having different colors and gradations are arranged side by side in the row direction and the column direction. Each arrangement position of the color patch 244 can be specified by a combination of a number in the number string 246 and an alphabet in the alphabet character string 248.

  In the color patches 244 illustrated in FIG. 12, ten color patches 244 are arranged without gaps in the vertical direction, and ten color patches 244 are arranged in the horizontal direction with gaps of a predetermined interval. The color of each color patch 244 is set to a predetermined value within a range of signal levels of CMYK values (0% to 100% as a percentage, 0 to 255 in the case of 8-bit gradation). The number string 246 is attached to the left part of each color patch 244 corresponding to the position as a character string of (01) to (10) in order from the top of FIG. On the other hand, the alphabetic character string 248 is attached to the upper part of each color patch 244 as the character string from (A) to (J) in order from the left in FIG.

The print information 250, the type of printing press 218, a serial number or registered name, the print mode to be described later, the media type 2 36, such as a print date and time are printed.

In the example of FIG. 12, spectral reflectance data is acquired from each of the 100 color patches 244. The spectral reflectance data can be configured to have, for example, 41 points of data in which the light wavelength ranges from λ ₁ = 400 nm to λ ₄₁ = 800 nm at equal intervals of 10 nm.

[Configuration of image processing apparatus]
FIG. 13 is a functional block diagram of the image processing apparatus 216. In FIG. 13, the same elements as those described in FIG. 11 are denoted by the same reference numerals, and the description thereof is omitted.

  The image processing apparatus 216 includes a control unit 260, a storage unit 262, a chart data generation unit 264, an optical physical property value estimation unit 266, a dot gain characteristic estimation unit 268, a colorimetric value prediction unit 270, and a grid point corresponding colorimetric value determination processing unit. 272 and a profile generation processing unit 274.

  The control unit 260 controls the operation of each unit of the image processing apparatus 216. The storage unit 262 is means for storing various data. The storage unit 262 includes a volatile memory and functions as a work memory. The storage unit 262 includes a nonvolatile memory, a hard disk drive, a solid state drive, or an appropriate combination thereof, and functions as a data storage. The storage unit 262 is connected to the control unit 260, the chart data generation unit 264, the optical property value estimation unit 266, the dot gain characteristic estimation unit 268, the color measurement value prediction unit 270, and the grid point corresponding color measurement value determination process via the bus 276. The unit 272 is connected to other functional units. Various data stored in the storage unit 262 is supplied to each functional unit as necessary.

  The storage unit 262 includes a light source spectral distribution data storage unit 278, a protective film-less printed matter spectral reflectance data storage unit 280, and a profile storage unit 282. The light source spectral distribution data storage unit 278 stores spectral distribution data of one or more types of light sources corresponding to the types of observation light sources. Preferably, spectral distribution data of a plurality of types of light sources are stored. Spectral distribution data can be added, deleted, or modified as necessary.

  The spectral reflectance data storage unit 280 stores the spectral reflectance data of the printed material without the protective film. The spectral reflectance data of the print without protective film can be obtained by measuring the color of the print without protective film with the colorimeter 30. Further, the spectral reflectance data of the printed matter without the protective film can be taken from the portable memory 234.

  The profile storage unit 282 stores various profiles such as a print standard color profile and a profile generated by the profile generation processing unit 274. An example of a standard printing color profile is the Japan Color (registered trademark) profile.

  The chart data generation unit 264 generates chart data such as the protective film color change characteristic grasp chart 10 (see FIG. 3) and the profile creation chart 50 (see FIG. 3).

  The optical property value estimation unit 266 performs processing for estimating the optical property value of the protective film. The optical property value estimation unit 266 performs a process of estimating a set of optical property values (in this example, a pair of the intrinsic reflectance R∞ and the scattering coefficient Sx) used in the Kubelka-Munk model 54. That is, the optical property value estimation unit 266 performs the optical property value estimation process 42 of the protective film described with reference to FIG. The processing function of the optical property value estimation unit 266 corresponds to one form of the “optical property value estimation function”. Information on the optical property value of the protective film estimated by the optical property value estimation unit 266 can be stored in the storage unit 262. Further, information on the optical property value of the protective film estimated by the optical property value estimating unit 266 can be accumulated in the database DB (see FIG. 11). When the optical property value of the protective film already stored in the storage unit 262 or the database DB can be used, the corresponding protective film is selected from the storage unit 262 or the database DB through an operation of selecting the type of the protective film using a predetermined GUI. It is possible to acquire information on optical property values.

  The dot gain characteristic estimation unit 268 in FIG. 13 performs a process of estimating dot gain characteristics due to the interaction between the protective film 20 and the printed material. The dot gain characteristic estimation unit 268 performs at least a process of estimating the primary color dot gain increase amount characteristic, and more preferably further performs a process of estimating the multi-color dot gain increase amount suppression rate. That is, the dot gain characteristic estimation unit 268 performs the primary color dot gain increase amount characteristic acquisition process 44 described with reference to FIG. In addition, the dot gain characteristic estimation unit 268 can be configured to perform the multi-color dot gain increase amount suppression rate acquisition process 46 described in FIG. The dot gain characteristic estimation unit 268 corresponds to one form of the “interaction characteristic estimation unit”, and the processing function corresponds to one form of the “interaction characteristic estimation function”.

  The colorimetric value prediction unit 270 is a processing unit that performs a process of predicting a colorimetric value of a printed matter with a protective film. The colorimetric value prediction unit 270 includes a first processing unit 284 and a second processing unit 286. The first processing unit 284 uses the optical property value estimated by the optical property value estimation unit 266 and based on the Kubelka-Munk model 54, the spectral reflectance of the printed matter with the protective film (KM predicted value Rkm described in FIG. 3). Equivalent to) is performed. The process performed by the first processing unit 284 corresponds to one form of the “first process process”. The colorimetric value prediction unit 270 has an arithmetic processing function that implements the colorimetric value calculation process 60 described in FIG.

The second processing unit 286 calculates the color predicted based on the spectral reflectance of the printed matter with protective film predicted by the first processing unit 284 or the spectral reflectance of the printed matter with protective film predicted by the first processing unit 284. The value (corresponding to the KM predicted colorimetric value XYZkm described in FIG. 3) is corrected based on the dot gain increase model 70. That is, the second processing unit 286 is calculated based on the spectral reflectance of the printed matter with protective film predicted by the first processing unit 284 or the spectral reflectance of the printed matter with protective film predicted by the first processing unit 284. The color prediction value is corrected using the dot gain increase amount characteristic estimated by the dot gain characteristic estimation unit 268. The process performed by the second processing unit 286 corresponds to one form of the “second process process”. The color prediction function by the colorimetric value prediction unit 270 corresponds to one form of the “prediction function”.

  The grid point-corresponding colorimetric value determination processing unit 272 applies to each grid point of the color conversion table based on the colorimetric value of the printed matter with a protective film predicted by the colorimetric value prediction unit 270 (referred to as “predicted colorimetric value”). Processing for determining the corresponding colorimetric value is performed. The process step by the grid point corresponding colorimetric value determination processing unit 272 corresponds to one form of the “determination process step”.

  The grid point of the color conversion table is, for example, a range (range or range) of signal values that can be taken for each of independent axes of color space (for example, C, M, Y, and K axes of CMYK). If the value range is expressed from 0% to 100%, grid points are set in increments of 10% for each axis (see Japanese Patent Application Laid-Open No. 2003-289446). It should be noted that the step size of the signal of each axis that defines the lattice point is not limited to “10%”. When an 8-bit integer value (0 to 255) is used as the signal value of the image signal, the signal value “0” is 0%, the signal value “255” is 100%, and a value between 0 and 255 is a linear type. Can be associated with each other.

  The grid point corresponding colorimetric value determination processing unit 272 assigns a corresponding colorimetric value (XYZ value or Lab value) to each CMYK grid point.

The profile generation processing unit 274 performs processing for generating a profile 74 (see FIG. 3 ) based on the colorimetric values corresponding to the respective grid points determined by the grid point corresponding colorimetric value determination processing unit 272. That is, the profile generation processing unit 274, based on the processing result of the grid point corresponding colorimetric value determination processing unit 272, the signal value of the device-dependent color space (denoted as “device value”) and the device-independent color space. Create a profile that represents the correspondence between coordinate values (denoted as “non-device values”).

  The profile generation processing unit 274 of this example includes a CMYK-XYZ profile indicating a correspondence relationship between a CMYK value as a device value and an XYZ value as a non-device value, or a CMYK value as a device value and a non-device value. A CMYK-Lab profile indicating the correspondence between Lab values is generated. The process of the profile generation processing unit 274 corresponds to one form of “generation process step”. The profile generated by the profile generation processing unit 274 can be stored in the profile storage unit 282.

  In addition to the above configuration, the image processing device 216 includes an interface unit 290 that enables connection to the display device 226 and a display control unit 292. In FIG. 13, “I / F” indicates “interface unit”. The display control unit 292 controls display on the display device 226. The image processing device 216 also has an interface unit 294 that enables connection to the input device 228, an interface unit 296 that enables connection to the colorimeter 30, and an interface that enables connection to a portable memory. A unit 298 and an interface unit 302 that enables connection with the editing device 214.

  The image processing apparatus 216 also includes a RIP (Raster Image Processor) unit 304, a color conversion processing unit 306, a printer driver 308, and a data output interface unit 310 for passing data to the printer 218 side. .

  The RIP unit 304 performs processing for expanding the PDL format of the electronic document supplied from the editing device 214 into a bitmap format. The RIP unit 304 converts a resolution conversion process corresponding to the resolution of the printing machine 218, an image enlargement / reduction process, an image rotation process corresponding to a print format, an image inversion process, Various image processing such as an appropriate combination of these can be performed.

  The color conversion processing unit 306 performs color conversion processing of image data using the input profile 314 and the output profile 316. The color conversion processing unit 306 uses input profile 314 to convert device-dependent data (device value) into device-independent data (non-device value), and output profile 316 to use device-independent data ( Output side profile processing for converting device-nondependent device values into device-dependent data (device values). The profile generated by the profile generation processing unit 274 can be used as the input profile 314 or the output profile 316.

  The term “input profile” is synonymous with “input profile”. The term “output profile” is synonymous with “output profile”. The color conversion processing unit 306 serves as a color conversion unit. The function of the color conversion processing by the color conversion processing unit 306 corresponds to the color conversion function.

  The input side profile processing using the input profile 314 and the output side profile processing using the output profile 316 may be performed in stages to perform color conversion, or the input profile 314 and the output profile 316 may be combined into one. A configuration may be adopted in which color conversion is performed by batch processing using a color conversion table collected in a table.

  Note that the color conversion processing unit 306 can correct the profile according to the printing mode of the printing machine 218. The print mode refers to the number of nozzles of the print head, the ink ejection timing (one-way / bidirectional) at the time of scanning of the print head, the number of passes, the number of ink colors and their types, the algorithm for creating data for ink ejection control, etc. Various settings related to printing.

  A color conversion processing unit 306 performs color conversion processing on device values (for example, CMYK values or RGB values) of the electronic document developed by the RIP unit 304, and device-dependent image data used for printing by the printing machine 218. (CMYK image data here) is generated.

  The printing press driver 308 generates print control data used for printing control by the printing press 218 from image data represented by CMYK values. In the case of the inkjet printer 218 shown in FIG. 11, ink ejection control data corresponding to each ink color (C, M, Y, K, LC, LM, or W) is created from the CMYK values. This ink ejection control data is associated with the ink ejection operation (ON / OFF, ink dot diameter size, etc.) of the printing machine 218 according to the data definition unique to the printing machine 218. In this case, conversion from a multi-tone image (continuous tone image) such as 8-bit to a low-tone image such as a binary image (a process called “quantization process” or “halftone process”) is required. Known algorithms such as a matrix method and an error diffusion method can be used.

  In FIG. 13, an inkjet printing machine that is a plateless digital printing machine is assumed as the printing machine 218, but a configuration in which the configuration of the printing machine driver 308 is mounted on the printing machine 218 side is also possible. In addition, when a plate-type printing machine using a printing plate is used instead of the ink jet printing machine, a plate making apparatus (not shown) such as a plate recorder for making a printing plate from image data and the plate making apparatus are used. And a printing machine that performs printing using a printing plate.

  An interface unit 296 that captures spectral reflectance information measured by the colorimeter 30 corresponds to one form of a “spectral reflectance acquisition unit”, and a function that captures spectral reflectance information is one of the “spectral reflectance acquisition function”. Corresponds to form. Further, the function of the control unit 260 that reads out spectral distribution data necessary for calculation from the light source spectral distribution data storage unit 278 and the database DB and provides it to the colorimetric value prediction unit 270 corresponds to one form of the “spectral distribution acquisition unit”. In addition, the function of capturing the spectral distribution data of the observation light source corresponds to one form of the “spectral distribution acquisition function”.

  The functions of the image processing device 216 can be realized by a computer system, and the image processing device 216 serves as a color conversion system. For example, a computer as a print color prediction device that realizes the color prediction function of the colorimetric value prediction unit 270 described in the image processing device 216, and a computer as a profile generation device that realizes the profile generation function of the profile generation processing unit 274 The function of the image processing device 216 can be realized in combination with a computer as a color conversion device that realizes the color conversion function of the color conversion processing unit 306.

[Print color prediction method]
FIG. 14 is a flowchart in which the steps of the printing color prediction method according to the present embodiment are organized.

  The printing color prediction method according to the present embodiment includes a spectral reflectance acquisition step (step S11) for acquiring the spectral reflectance of the printed material without the protective film, and an optical physical property value estimation step (step S12) for estimating the optical physical property value of the protective film. A spectral distribution acquisition step (step S13) for acquiring the spectral distribution of the observation light source, an interaction characteristic estimation step (step S14) for estimating a color change characteristic due to the interaction between the protective film and the printed material, and a printed material with a protective film. A colorimetric value prediction step (step S15) for predicting the colorimetric value. Step S15 corresponds to a “prediction process”.

  FIG. 15 is a flowchart showing the contents of the optical property value estimating step (step S12 in FIG. 14).

  As shown in FIG. 15, in the optical property value estimation step, the protective film is arranged on the step of obtaining the spectral reflectance of at least two types of bases without the protective film (step S21). A relational expression based on a mathematical model is established for each background using the spectral reflectance obtained in steps S21 and S22 (step S22), and a relational expression for each background is established. And a calculation step (step S23) for solving.

  FIG. 16 is a flowchart showing the contents of the colorimetric value prediction step (step S15 in FIG. 14).

  As shown in FIG. 16, in the colorimetric value prediction step, the optical reflectance of the protective film is used to predict the spectral reflectance of the printed matter with the protective film based on the Kubelka-Munk model (step S31). A colorimetric value calculation step (step S32) for calculating a predicted colorimetric value from the predicted spectral reflectance of the printed matter with the protective film, and a color change characteristic due to interaction with the predicted colorimetric value calculated in step S32. And a step of correcting the predicted colorimetric value by applying (Step S33).

  Step S31 corresponds to a “first processing step”, and step S33 corresponds to a “second processing step”.

  FIG. 17 is a flowchart showing another content example of the colorimetric value prediction step (step S15 in FIG. 14). In FIG. 17, the same step number is assigned to the same process as the example described in FIG. 16.

  As shown in FIG. 17, the colorimetric value prediction step is a step of predicting the spectral reflectance of the printed matter with the protective film based on the Kubelka-Munk model using the optical physical property value of the protective film (Step S31). A step of correcting the spectral reflectance by applying a color change characteristic due to interaction to the predicted spectral reflectance (step S34), and calculating a predicted colorimetric value from the predicted spectral reflectance corrected in step S34. And a colorimetric value calculation step (step S36) to be performed.

[Profile generation method]
FIG. 18 is a flowchart in which the steps of the profile generation method according to the present embodiment are organized. FIG. 18 includes the process (steps S11 to S15) of the printing color prediction method described in FIG. 14, and steps common to the steps described in FIG. Omitted. In the profile generation method of FIG. 18, in step S11, the spectral reflectance of each patch is acquired using a color chart without a protective film (profile creation chart 50 without a protective film) as a printed matter without a protective film. And the colorimetric value of each patch with a protective film is estimated by the process of step S12 to step S15. Each patch with a protective film corresponds to “a printed matter with a protective film”.

  Furthermore, the profile generation method according to the present embodiment is based on the colorimetric values (predicted colorimetric values) of each patch with a protective film predicted in step S15, and the measurement corresponding to each grid point of the multidimensional color conversion table. A determination processing step (step S41) for determining a color value, and a generation processing step (step S42) for generating a profile based on the correspondence between each grid point determined in step S41 and the colorimetric value.

[About color conversion]
The profile of the printed matter with protective film created above is applied to the color conversion processing unit 306 (see FIG. 13) and used for color conversion. Hereinafter, specific usage examples 1 to 4 will be described.

[Usage example 1: Example of carrying out color simulation (proof) of printed matter with protective film]
FIG. 19 is an explanatory diagram of Usage Example 1. Usage example 1 is a usage mode in which the color of a printed matter with a protective film is output to a monitor or printer for confirmation. In application example 1, the target protection is achieved by displaying the monitor or printing the output without a protective film on the printer without covering the protective film as an actual printed material (without actually creating the printed material with the protective film). It is the structure which can confirm the color of printed matter with a film | membrane.

  In the usage form shown in FIG. 19, the profile of the printed matter with the protective film is used as the input profile 314, and the profile of the proof output device 330 is used as the output profile 316. As the proof output device 330, a monitor 332 or a printer 334 can be used. The model and form of the proof output device 330 are not particularly limited. A display device 226 (see FIGS. 11 and 13) can be used as the monitor 332. Further, a printing machine 218 (see FIGS. 11 and 13) can be used as the printer 334.

  Image data indicating the original image 340 is color-converted by the color conversion processing unit 306 and output to the proof output device 330. In FIG. 19, CMYK value image data is shown as image data to be input to the color conversion processing unit 306.

  The color conversion processing unit 306 converts the CMYK value image data into the XYZ value or Lab value data by the input side profile processing using the input profile 314. Further, the output side profile processing using the output profile 316 converts the XYZ value or Lab value data into CMYK value or RGB value data. When the monitor 332 is used as the proof output device 330, RGB value data is provided from the color conversion processing unit 306 to the monitor 332 side. When the printer 334 is used as the proof output device 330, CMYK value data is provided from the color conversion processing unit 306 to the printer 334 side.

  In this way, the proof output device 330 generates the simulation proof 342 of the printed matter with the protective film. The simulation proof 342 of the printed matter with the protective film is a display image displayed on the monitor 332 or a printed matter printed by the printer 334 (the protective film is not covered).

  Based on the simulation 342 of the printed matter with the protective film thus obtained, the image of the finished color can be easily confirmed with the simulation proof 342 without actually creating the printed matter with the protective film.

  The operator looks at the simulation proof 342 of the printed matter with the protective film and adjusts the image as necessary. In FIG. 19, it is described as “image adjustment step S50”. The adjustment work in the image adjustment step S50 includes a process of correcting the signal value of the image data.

  By color-converting the image data after the adjustment in the image adjustment step S50 and outputting it to the proof output device 330, a simulation proof 342 of a printed matter with a protective film for the image data after adjustment can be obtained. By repeating such a work cycle once or a plurality of times, image data in which a desired finish can be expected is obtained.

  After the color is determined by the simulation proof 342, an output image 344 for printing is generated using the adjusted image data. A process of generating an output image 344 by performing color conversion processing from the document image 340 through the image adjustment process S50 is described as “image data color adjustment process S52” in FIG.

  Based on the output image 344 thus obtained, plate making and / or printing is performed, and a printed matter 346 is obtained. The step of performing plate making and / or printing is described as “plate making / printing step S54”. The printed matter 346 is a printed matter before coating the protective film, that is, in a state where the protective film is not coated. A protective film coating step S56 for coating the protective film is performed on the printed material 346, and a printed material 348 with a protective film is obtained.

  The color of the printed material 348 with the protective film, which is the printed material after the protective film coating in the protective film coating step S56, matches the color determined by the simulation proof 342 with high accuracy.

  According to the usage example 1 described with reference to FIG. 19, the finished color can be easily confirmed by the simulation proof 342 without actually creating a printed matter with a protective film at the stage of color adjustment. -> Image adjustment (correction)-> Finish check-> This makes it possible to quickly turn the cycle of color adjustment, and it is possible to shorten the time required for color adjustment work. And / or cost savings are possible.

[Usage example 2: Example of correcting color change by protective film]
FIG. 20 is an explanatory diagram of Usage Example 2. In the usage example 2, when there is a certain color reproduction target (target profile), the image data is corrected (color converted) in advance and printed so that the color after covering the protective film matches the color reproduction target. It is a usage form. If the target profile is printed as it is without considering the color change when the protective film is coated, the color changes after the protective film is coated, and a difference from the color reproduction target occurs. In this regard, when a protective film is coated on the printed matter printed according to Usage Example 2 of the present embodiment, the color that matches the color reproduction target color is obtained. Note that the expression “the colors match” is not limited to the case where the colors exactly match, but includes that the color difference falls within an allowable error range.

  20, elements that are the same as or similar to those in the configuration described in FIG. 19 are given the same reference numerals, and descriptions thereof are omitted.

  In the usage example 2 illustrated in FIG. 20, the target profile that is a color reproduction target is used as the input profile 314, and the profile of the printed matter with the protective film is used as the output profile 316.

  As an example of the color reproduction target, a standard print color such as Japan Color (registered trademark) or a print without a protective film can be used. When the print standard color is the color reproduction target, the print standard color profile is the target profile. In addition, when the color reproduction target is a printed material in a state where the protective film is not coated (printed material without protective film), the profile of the printed material without protective film (that is, the profile of the printing press) becomes the target profile.

Thus , the output image 344 obtained by performing color conversion of the document image 340 using the combination of the input profile 314 and the output profile 316 is an image in which the color change due to the protective film is corrected. Therefore, when the plate making / printing step S54 is performed based on the output image 344 and the obtained printed material 346 is coated with a protective film, the color of the printed material 348 with the protective film after the coating of the protective film matches the color of the reproduction target. Become.

[Usage example 3: Example of reproducing color of printed matter with protective film A with printed matter with protective film B]
FIG. 21 is an explanatory diagram of Usage Example 3. “Protective film A” and “protective film B” represent different protective films. When at least one of the material and thickness (film thickness) of the protective film is different, it is understood as “different protective films”.

  Usage example 3 is a usage mode in which the color of the printed material 350 with the protective film A, which is the target of color reproduction, is matched with the color of the printed material 352 with the protective film B. The usage example 3 is used when, for example, it is necessary to change the protective film to the protective film B after determining the color of the protective film A with the protective film A once. In FIG. 21, the same or similar elements as those described in FIG. 19 are denoted by the same reference numerals, and the description thereof is omitted.

  In the usage example 3 illustrated in FIG. 21, the profile of the printed material with the protective film A is used as the input profile 314, and the profile of the printed material with the protective film B is used as the output profile 316. Then, color conversion is performed on the data of the output image 354 when the printed matter with the protective film A is printed. By covering the printed matter 346 printed based on the output image 344 obtained by this color conversion processing with the protective film B, the printed matter 352 with the protective film B is obtained. The color of the printed matter 352 with the protective film B thus created matches the color of the printed matter 350 with the protective film A.

[Usage example 4: Example of reproducing the color of the printed matter with the protective film by the printing machine A by the printed matter with the protective film by the printing machine B]
FIG. 22 is an explanatory diagram of Usage Example 4. “Printing machine A” and “printing machine B” represent different printing machines. For example, the printing machine A is an offset printing machine, and the printing machine B is an inkjet printer. The usage example 4 is a usage mode in a case where colors (including the texture of the protective film) realized by the combination of the offset printing press and the protective film are reproduced by a combination of the inkjet printer and the protective film.

  In FIG. 22, a printed matter with a protective film obtained by coating a printed matter printed by the printing machine A with a protective film is referred to as a “printer A printed matter 360 with a protective film”. Further, a printed material with a protective film obtained by coating a printed material printed by the printing machine B with a protective film is referred to as a “printer B printed material 362 with a protective film”. The protective film of the printing machine A printed matter 360 with the protective film and the protective film of the printing machine B printed matter 362 with the protective film are the same protective film.

  In the color conversion usage mode described in Usage Example 1, the color reproduction of a printed matter with a protective film is simulated by a monitor or printer without actually covering the protective film. It cannot be reproduced without actually covering the protective film.

  By using the configuration as in the usage example 4, the offset printing machine (printing machine A) can be realized by combining the inkjet printer as the printing machine B and the protective film without actually printing with the offset printing machine (printing machine A). It becomes possible to simulate the color and texture of the finished product by combining the protective film. In FIG. 22, the printing machine A is not shown, and the printing machine B is denoted by reference numeral 366. 22, elements that are the same as or similar to the elements described in FIG. 19 are given the same reference numerals, and descriptions thereof are omitted.

  In the usage example 4 shown in FIG. 22, the profile of the printing press A with the protective film is used as the input profile 314, and the profile of the printing press B with the protective coating is used as the output profile 316. Then, the data of the output image 364 printed by the printing machine A is color-converted. Based on the output image 344 obtained by this color conversion processing, printing is performed by the printing machine B 366, and the obtained printed matter 346 is covered with a protective film, whereby the printing machine B printed matter 362 with a protective film is obtained. The printing machine B printed matter 362 with the protective film thus created matches the color and texture of the printing machine A printed matter with the protective film.

  Here, since the optical property value of the protective film is a characteristic unique to the protective film, when the same protective film is used on the printing press A side and the printing press B side, the same optical physical property value applies to both profile creations. it can. However, since the dot gain increasing characteristic is a change in optical dot gain due to the interaction between the protective film and the printed material, the characteristic varies depending on the type of halftone dot for printing. The halftone dot type includes the number of lines of an AM (Amplitude Modulation) screen and the difference in the type of AM halftone dot or FM (Frequency Modulation) halftone dot. That is, when the dot types are different on the printing machine A side and the printing machine B side, it is necessary to acquire the dot gain increase characteristic by the protective film in advance and apply a different dot gain increase characteristic to each.

[Color conversion processing flow]
As exemplified in Usage Example 1 to Usage Example 4, the profile of the printed matter with the protective film generated by the profile generation processing described in FIG. 18 is the input profile 314 or output profile of the color conversion processing unit 306 (see FIG. 13). 316 is used.

  FIG. 23 is a flowchart of the color conversion method according to this embodiment. The flowchart of FIG. 23 shows a comprehensive procedure common to the usage examples 1 to 4 described in FIGS.

  As a preparation necessary for the color conversion process of the present embodiment, a profile 174 of a printed matter with a protective film is generated by the profile generation process described with reference to FIG. The profile 174 of the printed matter with the protective film shown in FIG. 23 corresponds to the profile 74 described with reference to FIG.

  Then, the profile 174 of the printed matter with protective film is set as the input profile 314 of the input side profile process or the output profile 316 of the output side profile process (steps S111 and S112). Note that the processing order of the process of setting the input profile (step S111) and the process of setting the output profile (step S112) can be reversed, and both setting processes may be performed simultaneously.

  With regard to step S111 and step S112, in the usage example 1 described with reference to FIG. 19, the profile 174 of the printed matter with protective film is set as the input profile 314. In the usage example 2 described with reference to FIG. 20, the profile 174 of the printed matter with the protective film is set as the output profile 316. In the usage example 3 described with reference to FIG. 21, two types of profiles “printed product with protective film A” and “profile of printed material with protective film B” are generated as profiles 174 (see FIG. 23) of the printed material with protective film. “Profile of printed matter with protective film A” is set in the input profile 314, and “Profile of printed matter with protective film B” is set in the output profile 316. In the usage example 4 described with reference to FIG. 22, two types of profiles 174 of the printing machine A with the protective film and the profile of the printing machine B with the protective film are generated as the profile 174 of the printed film with the protective film. “Profile of printing machine A printed matter with protective film” is set as the input profile 314, and “Profile of printing machine B printed matter with protective film” is set as the output profile 316.

  After setting the input profile and the output profile in steps S111 and S112 in FIG. 23, color conversion is performed on the data of the target image 180 using these profiles (step S130). Data of the output image 184 as an image after color conversion is obtained by the color conversion processing in step S130.

  The target image 180 in the case of Usage Example 1 described with reference to FIG. 19 is the original image 340 or an adjusted image obtained by adjusting the image from the original image 340. Further, the output image 184 in the case of Usage Example 1 is the output image 344 shown in FIG. 19 or the color-converted image given to the proof output device 330.

  The target image 180 in the case of Usage Example 2 described with reference to FIG. 20 is a document image 340. The target image 180 in the case of Usage Example 3 described with reference to FIG. 21 is an output image 354 of the printed matter with the protective film A. The target image 180 in the usage example 4 described with reference to FIG. 22 is the output image 364 of the printing machine A. 20 to 22 corresponds to the output image 184 shown in FIG.

  FIG. 24 is a flowchart illustrating an example of the color conversion method according to the present embodiment. The flowchart in FIG. 24 shows a comprehensive procedure common to the configurations exemplified in Usage Example 3 and Usage Example 4. In FIG. 24, the profile generation process described in FIG. 18 is applied to two types of printed materials to obtain a first profile 174A and a second profile 174B, which are used as an input profile and an output profile, respectively. It is a flow to perform color conversion.

  The reference numerals such as step numbers shown in the flowchart of FIG. 24 correspond to the reference numerals used in the description of the flowcharts described in FIGS. 18 and 23, and are the same as the elements and processes common to the flowchart described in FIG. The sign of was used. In FIG. 24, “A” and “B” added to the end of the code represent the difference between the two types of printed matter. Since the contents of the steps shown in FIG. 24 have been described with reference to FIGS. 18 and 23, detailed description thereof will be omitted with the description of FIG.

  The step of acquiring the spectral reflectance of the first profile creation chart without the protective film shown in step S11A of FIG. 24 corresponds to the step of acquiring “the spectral reflectance of the first color chart as the first printed matter”. Yes. The colorimetric values of the “first profile creation chart with a protective film” as the first printed matter with the protective film are predicted by the print color prediction processing from step S11A to step S15A in FIG. Then, colorimetric values corresponding to the respective grid points of the first color conversion table are determined based on the obtained predicted colorimetric values (step S41A), and a first profile is generated (step S42A). The first profile 174A thus obtained is set as an input profile (step S111A).

Similarly, the step of acquiring the spectral reflectance of the second profile creation chart without the protective film shown in step S11B corresponds to the step of acquiring “the spectral reflectance of the second color chart as the second printed matter”. Yes. The colorimetric values of the “second profile creation chart with protective film” as the second protective film-attached printed matter are predicted by the print color prediction processing in steps S11B to S15B in FIG. Then, colorimetric values corresponding to the respective grid points of the second color conversion table are determined based on the obtained predicted colorimetric values (step S41B), and a second profile is generated (step S42B). The second profile 174B thus obtained is set as an output profile (step S112 B ).

  Usage Example 3 described in FIG. 21 is an example in which the first protective film and the second protective film are different protective films. The “profile of the printed matter with protective film A” described in Application Example 3 corresponds to the first profile 174A, and the “profile of the printed matter with protective film B” corresponds to the second profile 174B.

  The usage example 4 described in FIG. 22 is an example in which the first protective film and the second protective film are the same protective film. The “profile of the printing press A with the protective film” described in the usage example 4 corresponds to the first profile 174A, and the “profile of the printing press B with the protective coating” corresponds to the second profile 174B.

[About black spot correction]
As another additional configuration related to the color conversion processing described above, a configuration in which black point correction is performed at the time of color conversion is also possible. Since the color reproduction range (gamut) varies greatly depending on the type of protective film, color conversion aiming at colorimetric matching may cause undesired results because the shadow-side gradation is crushed. Therefore, it is preferable to include a configuration that can add black spot correction processing.

  The black point correction is a color value of a black point on a boundary of a gamut (hereinafter referred to as “first gamut”) according to a first profile and a boundary of a gamut (hereinafter referred to as “second gamut”) according to a second profile. Color conversion processing for mapping so as to match the color value of the black point.

As an algorithm for performing black point correction, for example, a method disclosed in Japanese Patent Application Laid-Open No. 2004-153554 can be used. An outline of this method will be described with reference to FIGS. 25 (A) to (C).

FIG 2 5 (A) ~ (C ) are diagrams illustrating the gamut conversion process by black point compensation. FIG 2 5 (A) is a graph showing the positional relationship between the first gamut 370 before (enclosed by a solid line area) and the second gamut 372 (region surrounded by a broken line) for the black point compensation. The horizontal axis of this graph is defined as a ^* , and the vertical axis is defined as L ^* , which represents a cross-sectional view of the three-dimensional color space L ^* a ^* b ^* . The same applies to the axis definitions of the graphs shown in FIGS. 25 (B) and 25 (C).

  For example, it is assumed that the first gamut 370 is a gamut when observed under the light source PS without covering the first medium with a protective film. The second gamut 372 is a gamut when the first medium is covered with a protective film and observed under the light source PS. That is, consider a case where a difference between the first gamut 370 and the second gamut 372 occurs depending on whether or not the protective film is covered.

It is assumed that the white point wt1 in the first gamut 370 is (L ^* _wt1 , a ^* _wt1 , b ^* _wt1 ) and the black point bk1 is (L ^* _bk1 , a ^* _bk1 , b ^* _bk1 ). Further, it is assumed that the white point wt2 in the second gamut 372 is (L ^* _wt2 , a ^* _wt2 , b ^* _wt2 ) and the black point bk2 is (L ^* _bk2 , a ^* _bk2 , b ^* _bk2 ).

First, each gamut is translated downward so that the black point bk1 of the first gamut 370 and the black point bk2 of the second gamut 372 coincide with each other. When the color values after black point correction of the first gamut 370 and the second gamut 372 are (L ₁ ′, a ₁ ′, b ₁ ′) and (L ₂ ′, a ₂ ′, b ₂ ′), respectively, The gamut conversion equation is expressed by the following equations (11) and (12).
(L ₁ ′, a ₁ ′, b ₁ ′) = (L ^* −L ^* _bk1 , a ^* −a ^* _bk1 , b ^* −b ^* _bk1 ) (11)
_{(L 2 ', a 2'} , b 2 ') = (L * -L * bk2, a * -a * bk2, b * -b * bk2) ... (12)
In this way, the first gamut 370s after translation, second gamut 372s is obtained (see FIG. 2 5 (B)). As shown in FIG. 2 5 (B), 'color values, black dots bk2 converted black dots bk2' black spot bk1 converted black point bk1 color values is consistent with both (0,0,0).

  Next, gamut conversion is performed so that the white point wt1 'of the first gamut 370s matches the white point wt2' of the second gamut 372s while maintaining the match between bk1 'and bk2'. Here, since the area of the first gamut 370s is larger than the area of the second gamut 372s, conversion is performed to enlarge the second gamut 372s upward.

  In the present embodiment, a method of matching white spots while fixing black spots is applied by applying Von-Kries transformation, which is a kind of chromatic adaptation model. The conversion algorithm is not limited to this. For example, gamut similarity conversion (change of ratio), Bradford conversion, CIECAM97s conversion, CIECAM02s conversion, or the like may be used.

  The Von-Kries conversion equation from the second gamut 372s to the second gamut 372k is expressed by the following equation (13).

Here, (X ′, Y ′, Z ′) is a color value before gamut conversion, (X ″, Y ″, Z ″) is a color value after gamut conversion, and [M ⁻¹ ] is [ M] is an inverse transformation matrix, and [M] is a 3 × 3 matrix for converting the color value XYZ into the color value PQR related to the response of the eye cone. 14)

Note that the color values of the white point wt1 ′ and the white point wt2 ′ are ( _Xwt1 ′, _Ywt1 ′, _Zwt1 ′) and ( _Xwt2 ′, _Ywt2 ′, _Zwt2 ′), respectively.

  By the way, instead of performing the gamut conversion in two steps as described above, the second gamut 372 may be directly converted to the second gamut 372k. The conversion equation can be expressed as the following equations (15) and (16).

The color values of the white point wt2 and the black point bk2 of the second gamut 372 are (X _wt , Y _wt , Z _wt ) and (X _bk , Y _bk , Z _bk ), respectively, and the white point wt2 of the second gamut 372k The color values of “, black point bk2” are (X _wt ″, Y _wt ″, Z _wt ″) and (X _bk ″, Y _bk ″, Z _bk ″), respectively.

By the way, the relationship between L ^* a ^* b ^* and XYZ is expressed by the following equations (17) to (19).

Here, (X _ST , Y _ST , Z _ST ) represents a reference color value. The color values (L ^* , a ^* , b ^* ) can be uniquely converted into the color values (X, Y, Z) by the inverse transformation of the equations (17) to (19).

In this way, the second gamut 372k after Von-Kries conversion is obtained. As shown in FIG. 2 5 (C), 'color values, white point wt2' white point wt1 color values white point wt2 "after conversion are consistent.

  As described above, mapping is performed so that the color value of the black point related to the first profile matches the color value of the black point related to the second profile (in this embodiment, the gamut is moved in parallel), thereby In particular, the color reproducibility in the shadow area can be substantially matched between the printed material and the second printed material.

[Adjustment of color change characteristic parameter]
It is preferable that the parameter obtained by the color change characteristic parameter estimation process 40 described in FIG. 3 can be adjusted by a GUI (Graphical User Interface).

  FIG. 26 is a diagram showing an example of an adjustment GUI screen for adjusting the color change characteristic parameter. The description of “protective film parameter” in FIG. 26 means “color change characteristic parameter”. The protective film parameter adjustment screen 380 shown in FIG. 26 is for adjusting the optical physical property value adjustment GUI display area 382 for adjusting the optical physical property value of the protective film, and the parameter of the dot gain characteristic due to the interaction between the protective film and the printed material. Dot gain characteristic adjustment GUI display area 384.

  26 shows an example in which the optical property value adjustment GUI display area 382 is arranged in the upper part of the protective film parameter adjustment screen 380, and the dot gain characteristic adjustment GUI display area 384 is arranged in the lower part of the protective film parameter adjustment screen 380. However, the form of the display layout on the screen is not limited to the example of FIG. The arrangement relation between the upper stage and the lower stage may be exchanged, or may be arranged side by side. Alternatively, the optical property value adjustment GUI display area 382 and the dot gain characteristic adjustment GUI display area 384 may be displayed in separate windows.

  The optical property value adjustment GUI display area 382 includes a coordinate display field 390, two text boxes 392 and 394, a slider bar gauge 400, a slider 402, one text box 404, and a graph display field 406. Have.

The coordinate display column 390 displays adjustable ranges (both 0.0 to 2.0) for each of the scattering coefficient Sx and the absorption coefficient Kx. The horizontal axis represents the adjustment amount Cs of the scattering coefficient, and the vertical axis represents the adjustment amount Ck of the absorption coefficient. The numerical values of the adjustment amounts Cs and Ck act as adjustment coefficients (multipliers) for the scattering coefficient Sx and the absorption coefficient Kx, respectively. When there is no adjustment, it is “1.0”.

  The coordinate display field 390 indicates the balance between the scattering coefficient and the absorption coefficient by the coordinate point 396. The balance can be set by moving the coordinate point 396 by a mouse operation or a touch operation of the input device 228 (see FIG. 13). The position of the coordinate point 396 and the numerical input of the adjustment amounts (Cs, Ck) are linked.

A text box 392 arranged at the bottom of the coordinate display field 390 displays a numerical value of the scattering coefficient adjustment amount Cs. In the figure, “1.2” is exemplified as the numerical value of the adjustment amount Cs. A numerical value of the absorption coefficient adjustment amount Ck is displayed in a text box 394 arranged on the left side of the coordinate display field 390. In the figure, “0.8” is exemplified as the numerical value of the adjustment amount Ck. It is also possible to directly change the numerical values in the text boxes 392 and 394 by a key input operation or the like of the input device 228 (see FIG. 13), and the position of the coordinate point 396 is changed in conjunction with the change of the numerical values . Gauge 400 is displaying the range (0.0 to 2.0) can be set as the thickness of the protective layer (x). The horizontal axis of the gauge 400 represents the film thickness adjustment amount Cx. The numerical value of the film thickness adjustment amount Cx acts as an adjustment coefficient (multiplier) for the film thickness (x). When there is no adjustment, it is “1.0”. The thickness of the protective film can be adjusted by moving the slider 402 in the horizontal direction in FIG. 26 by a mouse operation or a touch operation of the input device 228 (see FIG. 13). A numerical value of the film thickness adjustment amount Cx is displayed in a text box 404 arranged on the left side of the gauge 400. In the figure, “0.8” is exemplified as the numerical value of the film thickness adjustment amount Cx. The slider bar and the numerical value input by the gauge 400 and the slider 402 are linked to each other, and a desired numerical value is input to the text box 404 by a key input operation from the input device 228 (see FIG. 13). The thickness (x) value can be changed.

  In the graph display field 406, parameters of optical property values according to the current adjustment state are displayed. That is, the graph display column 406 displays a graph of the scattering coefficient Sx and the absorption coefficient Kx in the current adjustment state. The horizontal axis of the graph indicates the wavelength (unit: nanometer [nm]), and the vertical axis indicates the value of each coefficient.

  When the scattering / absorption parameters of the protective film are the adjustment amount Cs of the scattering coefficient, the adjustment amount Ck of the absorption coefficient, and the adjustment amount Cx of the film thickness, the adjusted parameters are expressed by the following equations for each wavelength. calculate.

Kx (after adjustment) = Kx (before adjustment) × Ck × Cx
Sx (after adjustment) = Sx (before adjustment) × Cs × Cx
Next, the dot gain characteristic adjustment GUI display area 384 will be described. The dot gain characteristic adjustment GUI display area 384 includes a graph display field 410, three slider bar gauges 420, 430, 440, sliders 422, 432, 442 for each gauge 420, 430, 440, and three text boxes 424. 434, 444.

  The graph display column 410 displays a graph of the dot gain increase amount characteristic of the primary color. In the graph shown here, as described with reference to FIG. 3, the horizontal axis indicates the real area ratio without the protective film, and the vertical axis indicates the primary color dot gain increase amount (Δdg). With respect to the graph of each color, the parameter value can be adjusted by moving a point on the graph by a mouse operation or a touch operation of the input device 228 (see FIG. 13).

  The gauge 420 and the slider 422 are slider bars for adjusting the dot gain increase amount suppression rate of the secondary color. The gauge 420 displays a range (0.0 to 1.0) that can be set as the dot gain increase amount suppression rate. In a text box 424 arranged on the left side of the gauge 420, a numerical value of the secondary color dot gain increase suppression rate is displayed.

  The gauge 430 and the slider 432 are slider bars for adjusting the dot gain increase suppression rate of the tertiary color. In the text box 434 arranged on the left side of the gauge 430, the numerical value of the dot gain increase amount suppression rate of the tertiary color is displayed.

The gauge 440 and the slider 442 are slider bars for adjusting the dot gain increase amount suppression rate of the quaternary color. In the text box 4 4 4 arranged on the left side of the gauge 440, the numerical value of the dot gain increase amount suppression rate of the quaternary color is displayed.

  The point that the operation of the sliders 422, 432, and 442 and the numerical input are linked, and the direct numerical input to the text boxes 424, 434, and 444 is possible. The relationship is similar to that in box 404.

  The protective film parameter adjustment screen 380 shown in FIG. 26 includes an OK button 452, a simulation display button 454, and a cancel button 456. The description “button” means a GUI button. Note that the expression “push” for the GUI button includes an operation of inputting a command corresponding to the button, such as clicking, touching, or mouse over.

  When the OK button 452 is pressed, the parameter adjustment value setting is saved. When the cancel button 456 is pressed, the investigation work is canceled, the protective film parameter adjustment screen 380 is closed, and the setting work is ended.

  When the simulation display button 454 is pressed, a printing color prediction simulation is started on the screen of the display device 226 (see FIG. 13). That is, the print color of the printed matter with the protective film can be reproduced on the screen of the display device 226 in a pseudo manner so that the appearance can be predicted and evaluated. The display device 226 is preferably a high-brightness and high-definition monitor.

  The result of adjustment on the protective film parameter adjustment screen 380 described in FIG. 26 can be confirmed by displaying a simulation on the monitor. The color conversion of the simulation display is as described in [Usage Example 1].

[About profile adjustment]
A configuration capable of further adjusting the profile of the printed matter with protective film created by the profile generation processing unit 274 of FIG. 13 may be added, and the adjusted profile may be used as the profile of the printed matter with protective film at the time of color conversion processing. .

As a method of adjusting the profile, for example, the LUT (corresponding relationship between halftone dot area ratio on the data → colorimetric value) of the print product without protective film and the LUT (corresponding relationship between halftone dot area ratio on data) → colorimetric value There is a method of blending the correspondence of values) at a predetermined ratio. Specifically, the weighted average value of the output values (colorimetric values) of the two LUTs for the same data halftone dot area ratio is set as the output value for the data halftone dot area ratio of the LUT of the adjusted profile. That is, the LUT output value of the profile of the print with no protective film for a certain dot area ratio on data is (X ₀ , Y ₀ , Z ₀ ), and the LUT output value of the profile of the print with protective film is (X ₁ , Y ₁ , Z ₁ ) When the weight is set to w (0 ≦ w ≦ 1), the adjusted colorimetric values (X ₁ ′, Y ₁ ′, Z ₁ ′) are as follows. When w = 1, it matches the profile with the protective film before adjustment.

X ₁ ′ = (1−w) · X ₀ + w · X ₁
Y ₁ ′ = (1−w) · Y ₀ + w · Y ₁
Z ₁ ′ = (1−w) · Z ₀ + w · Z ₁
This is applied to all grid points of the LUT, and the colorimetric values that are the output values of the LUT are replaced with (X ₁ ′, Y ₁ ′, Z ₁ ′).

  By adopting a configuration capable of such adjustment, it is possible to easily adjust the effect of correcting the color change by the protective film and the effect of the simulation. For example, when it is desired to slightly reduce the effect of color correction, it is possible to use such as adjusting w from “1.0” to “0.9”.

[Another configuration example of the image processing apparatus]
FIG. 27 is a functional block diagram showing another configuration example of the image processing apparatus 216. In FIG. 27, elements that are the same as or similar to those shown in FIG. 13 are given the same reference numerals, and descriptions thereof are omitted. The image processing apparatus 216 illustrated in FIG. 27 includes a black point correction processing unit 462, a parameter adjustment processing unit 464, and a profile adjustment processing unit 466 in addition to the configuration illustrated in FIG.

  The black spot correction processing unit 462 performs the black spot correction process described with reference to FIGS. The parameter adjustment processing unit 464 performs the color change parameter adjustment processing described with reference to FIG. The profile adjustment processing unit 466 performs the above-described profile adjustment processing and generates an adjusted profile.

<Regarding a program for causing a computer to function as an image processing apparatus>
As the image processing apparatus 216 described in the above-described embodiment, a program for causing a computer to function is recorded on a CD-ROM, a magnetic disk, or other computer-readable medium (a non-transitory information storage medium as a tangible object), and the information storage It is possible to provide the program through a medium. Instead of providing the program by storing the program in such an information storage medium, it is also possible to provide the program signal as a download service using a communication network such as the Internet. It is also possible to provide the image processing apparatus 216 as an application server and provide a service for providing a processing function through a communication network.

  In addition, by incorporating this program into a computer, each function of the image processing apparatus 216 can be realized by the computer, and the image processing function described in the above embodiment can be realized.

[Advantages of the embodiment]
According to the above-described embodiment of the present invention, the process by the dot gain increase model 70 as the halftone dot gain correction process based on the color change characteristic due to the interaction between the protective film and the underlying printed matter is included. Thereby, compared with a prior art, the color prediction precision of printed matter with a protective film improves further. Further, by performing color conversion processing using a profile created from the color prediction result described in this embodiment, the accuracy of simulation and the accuracy of color correction are improved.

  In the embodiment of the present invention described above, the configuration requirements can be appropriately changed, added, and deleted without departing from the spirit of the present invention. The present invention is not limited to the embodiments described above, and many modifications can be made by those having ordinary knowledge in the field within the technical idea of the present invention.

[Modification Example 1]
In this embodiment, the number of color patches 244 included in the color chart 238c of FIG. 12 exemplified as the profile creation chart 50 is 100, the number of spectral data is 41 points, and the interval between light wavelengths is 10 nm. The image processing time and the like may be comprehensively taken into consideration so that these can be freely changed.

[Modification Example 2]
In this embodiment, the Kubelka-Munk model is used as a colorimetric value prediction formula for a printed matter with a protective film. However, the present invention is not limited to this, and a modified formula of the Kubelka-Munk model or another mathematical model is also applied. Needless to say, it can be done. Similarly, in the present embodiment, the Murray-Davies formula is used as a formula for calculating the area ratio of the halftone dots. However, the present invention is not limited to this, and a modified formula of the Murray-Davies formula or another mathematical model is also applied. Needless to say, you can.

[Modification Example 3]
Furthermore, in the embodiment shown in FIG. 11, the configuration using the ink jet type printing machine 218 has been described. However, the present invention is not limited to this, and plate / non-plate printing such as electrophotography, thermal method, or flexographic printing is possible. Regardless, the present invention can also be applied to configurations that employ printing machines of various printing methods.

  DESCRIPTION OF SYMBOLS 10 ... Protective film color change characteristic grasp chart, 20 ... Protective film, 30 ... Colorimeter, 50 ... Profile creation chart, 54 ... Kubelka-Munk model, 70 ... Dot gain increase model, 210 ... Printing system, 214 ... Editing device 216: Image processing apparatus, 218: Printing machine, 220: Laminating apparatus, 266: Optical property value estimation unit, 268 ... Dot gain characteristic estimation unit, 270 ... Color measurement value prediction unit, 272 ... Color measurement value corresponding to grid points Decision processing unit, 274 ... Profile generation processing unit, 284 ... First processing unit, 286 ... Second processing unit, 306 ... Color conversion processing unit, 314 ... Input profile, 316 ... Output profile

Claims (15)

A print color prediction method for predicting color reproduction of a printed material with a protective film in which a printed material is coated with a protective film,
A spectral reflectance acquisition step of acquiring a spectral reflectance of a protective film non-covering region of the printed matter having a printing surface on which the protective film is uncoated;
An optical property value estimating step for performing a process of estimating the optical property value of the protective film;
Spectral distribution acquisition step of acquiring the spectral distribution of the observation light source of the printed matter with protective film,
An interaction characteristic estimation step for performing a process of estimating a color change characteristic due to the interaction between the protective printed film and the underlying printed matter coated with the protective film;
Spectral reflectance of the printed matter acquired by the spectral reflectance acquisition step, optical property value of the protective film estimated by the optical property value estimation step, spectral distribution of the observation light source acquired by the spectral distribution acquisition step And a predicting step of predicting a colorimetric value of the printed matter with a protective film based on the color change property due to the interaction estimated by the interaction property estimating step,
Bei to give a,
The interaction characteristic estimation step includes dot gain characteristics when there is a protective film in a state where the protective film is coated on each of a plurality of types of bases composed of monochrome gradations having different dot area ratios, and the plurality of types Performing the process of estimating the color change characteristics due to the change in dot gain as the interaction, based on the dot gain characteristics when there is no protective film in which the protective film is in an uncovered state for each of the backgrounds of Print color prediction method. In the interaction characteristic estimation step, a step of calculating a dot gain increase amount indicating a difference between a dot gain amount of the primary color when the protective film is present and a dot gain amount of the primary color when the protective film is absent. When,
Identifying the relationship between the dot area ratio of the base and the dot gain increase in the absence of the protective film;
The printing color prediction method according to claim 1 , wherein:   3. The print color prediction method according to claim 1, wherein the color change characteristic due to the interaction is a dot gain characteristic indicating a dot gain increase amount due to the interaction between the protective film and the printed matter on the base. A print color prediction method for predicting color reproduction of a printed material with a protective film in which a printed material is coated with a protective film,
A spectral reflectance acquisition step of acquiring a spectral reflectance of a protective film non-covering region of the printed matter having a printing surface on which the protective film is uncoated;
An optical property value estimating step for performing a process of estimating the optical property value of the protective film;
Spectral distribution acquisition step of acquiring the spectral distribution of the observation light source of the printed matter with protective film,
An interaction characteristic estimation step for performing a process of estimating a color change characteristic due to the interaction between the protective printed film and the underlying printed matter coated with the protective film;
Spectral reflectance of the printed matter acquired by the spectral reflectance acquisition step, optical property value of the protective film estimated by the optical property value estimation step, spectral distribution of the observation light source acquired by the spectral distribution acquisition step And a predicting step of predicting a colorimetric value of the printed matter with a protective film based on the color change property due to the interaction estimated by the interaction property estimating step,
Bei to give a,
The printing color prediction method , wherein the color change characteristic due to the interaction is a dot gain characteristic indicating a dot gain increase amount due to the interaction between the protective film and the printed matter on the base . Optical material characteristic value of the protective film is specular reflectance for each light wavelength of the protective layer, scattering coefficient, and of the absorption coefficients, including independent two optical physical properties, any one of claims 1 4 The printing color prediction method described in 1. In the optical property value estimation step,
A first acquisition step of acquiring spectral reflectance of at least two kinds of bases in which the protective film is uncoated;
A second obtaining step of obtaining a spectral reflectance in a state where the protective film is disposed on each of the at least two kinds of bases;
Using each spectral reflectance acquired in each step of the first acquisition step and the second acquisition step and the optical physical property value of the protective film as an unknown, a mathematical model for each of the at least two types of bases A calculation step of obtaining a relational expression based on and solving the relational expression for each base simultaneously;
Contains
Wherein estimating the optical material characteristic value of the protective film on the basis of the calculation of the calculating step, the print color predicting method according to any one of claims 1 to 5. In the interaction characteristic estimation step, a correction parameter acquisition step of acquiring a correction parameter for correcting data indicating a color change characteristic due to the interaction between the printed matter of the base coated with the protective film and the protective film;
A correction processing step of correcting the color change characteristic using the correction parameter;
The print color prediction method according to any one of claims 1 to 6, wherein: The data indicating the color change characteristic due to the interaction is data indicating the dot gain increase amount characteristic of the primary color,
The print color prediction method according to claim 7, wherein the correction parameter is a parameter indicating a suppression rate of the dot gain increase amount related to a secondary color or higher. In the prediction step, a first processing step of performing a process of predicting a spectral reflectance of the printed matter with a protective film based on a mathematical model using the optical property value estimated in the optical property value estimation step;
The predicted color value calculated based on the spectral reflectance of the printed matter with protective film predicted by the first processing step or the spectral reflectance of the printed matter with protective film predicted by the first processing step, The print color prediction method according to claim 1, further comprising: a second processing step of correcting using the color change characteristic due to the interaction estimated by the action characteristic estimation step. Using the printing color prediction method according to any one of claims 1 to 9, predicting a colorimetric value of the printed matter with a protective film from a spectral reflectance of a color chart as the printed matter,
Further, a determination processing step for determining a colorimetric value corresponding to each grid point of the color conversion table based on the predicted colorimetric value of the printed matter with a protective film,
A generation processing step of generating a profile based on a colorimetric value corresponding to each grid point of the color conversion table;
A profile generation method comprising: A print color prediction device for predicting color reproduction of a printed matter with a protective film in which a printed material is coated with a protective film,
A spectral reflectance acquisition unit that acquires a spectral reflectance of a protective film uncoated region of the printed matter having a printing surface on which the protective film is uncoated;
An optical property value estimator for performing a process of estimating the optical property value of the protective film;
A spectral distribution acquisition unit for acquiring a spectral distribution of an observation light source of the printed matter with a protective film;
An interaction characteristic estimation unit for performing a process of estimating a color change characteristic due to the interaction between the protective printed film and the underlying printed matter covered with the protective film;
Spectral reflectance of the printed matter acquired by the spectral reflectance acquisition unit, optical property value of the protective film estimated by the optical property value estimation unit, spectral distribution of the observation light source acquired by the spectral distribution acquisition unit And a prediction unit that predicts a colorimetric value of the printed matter with a protective film based on the color change characteristic due to the interaction estimated by the interaction characteristic estimation unit,
Bei to give a,
The interaction characteristic estimation unit includes a plurality of types of dot gain characteristics when there is a protective film in a state where the protective film is coated on each of a plurality of types of bases composed of monochrome gradations having different halftone dot area ratios. Performing the process of estimating the color change characteristics due to the change in dot gain as the interaction, based on the dot gain characteristics when there is no protective film in which the protective film is in an uncovered state for each of the backgrounds of Print color prediction device. A print color prediction device for predicting color reproduction of a printed matter with a protective film in which a printed material is coated with a protective film,
A spectral reflectance acquisition unit that acquires a spectral reflectance of a protective film uncoated region of the printed matter having a printing surface on which the protective film is uncoated;
An optical property value estimator for performing a process of estimating the optical property value of the protective film;
A spectral distribution acquisition unit for acquiring a spectral distribution of an observation light source of the printed matter with a protective film;
An interaction characteristic estimation unit for performing a process of estimating a color change characteristic due to the interaction between the protective printed film and the underlying printed matter covered with the protective film;
Spectral reflectance of the printed matter acquired by the spectral reflectance acquisition unit, optical property value of the protective film estimated by the optical property value estimation unit, spectral distribution of the observation light source acquired by the spectral distribution acquisition unit And a prediction unit that predicts a colorimetric value of the printed matter with a protective film based on the color change characteristic due to the interaction estimated by the interaction characteristic estimation unit,
Bei to give a,
The printing color prediction apparatus , wherein the color change characteristic due to the interaction is a dot gain characteristic indicating a dot gain increase amount due to the interaction between the protective film and the printed matter on the base . A printing color prediction apparatus according to claim 11 or 12 ,
A determination processing unit that determines a colorimetric value corresponding to each grid point of the color conversion table based on a colorimetric value of the printed material with a protective film predicted by the prediction unit from a spectral reflectance of a color chart as the printed material;
A generation processing unit that generates a profile based on colorimetric values corresponding to each grid point of the color conversion table;
A profile generation apparatus comprising: A program for causing a computer to realize a function of predicting color reproduction of a printed material with a protective film in which a printed material is coated with a protective film,
A spectral reflectance acquisition function for acquiring a spectral reflectance of a protective film uncoated region of the printed matter having a printing surface on which the protective film is uncoated;
An optical property value estimation function for performing a process of estimating the optical property value of the protective film;
A spectral distribution acquisition function for acquiring a spectral distribution of an observation light source of the printed matter with protective film;
An interaction characteristic estimation function for performing a process of estimating a color change characteristic due to the interaction between the protective printed material and the underlying printed matter covered with the protective film;
Spectral reflectance of the printed matter acquired by the spectral reflectance acquisition function, optical property value of the protective film estimated by the optical property value estimation function, spectral distribution of the observation light source acquired by the spectral distribution acquisition function And a prediction function for predicting a colorimetric value of the printed matter with a protective film based on a color change characteristic due to the interaction estimated by the interaction characteristic estimation function;
A program for realizing the to the computer,
The interaction characteristic estimation function includes a plurality of types of dot gain characteristics when there is a protective film in which the protective film is coated on each of a plurality of types of bases composed of monochrome gradations having different halftone dot area ratios. Performing the process of estimating the color change characteristics due to the change in dot gain as the interaction, based on the dot gain characteristics when there is no protective film in which the protective film is in an uncovered state for each of the backgrounds of Program . A program for causing a computer to realize a function of predicting color reproduction of a printed material with a protective film in which a printed material is coated with a protective film,
A spectral reflectance acquisition function for acquiring a spectral reflectance of a protective film uncoated region of the printed matter having a printing surface on which the protective film is uncoated;
An optical property value estimation function for performing a process of estimating the optical property value of the protective film;
A spectral distribution acquisition function for acquiring a spectral distribution of an observation light source of the printed matter with protective film;
An interaction characteristic estimation function for performing a process of estimating a color change characteristic due to the interaction between the protective printed material and the underlying printed matter covered with the protective film;
Spectral reflectance of the printed matter acquired by the spectral reflectance acquisition function, optical property value of the protective film estimated by the optical property value estimation function, spectral distribution of the observation light source acquired by the spectral distribution acquisition function And a prediction function for predicting a colorimetric value of the printed matter with a protective film based on a color change characteristic due to the interaction estimated by the interaction characteristic estimation function;
A program for realizing the to the computer,
A program in which the color change characteristic due to the interaction is a dot gain characteristic indicating a dot gain increase amount due to an interaction between the protective film and the printed matter on the base.