JP2005142994A - Color estimate method, color adjustment method, and color image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a color estimate method for estimating a color obtained by printing ink on print paper whose surface state differs from that of print paper used for measurement or estimating a color obtained by overprinting a plurality of inks on the print paper on the basis of a value of a color characteristic obtained by measuring the plurality of inks printed on the measurement print paper. <P>SOLUTION: The color estimate method includes: a first measurement step of measuring a value of a color characteristic of a color material on a recording medium on which the color material is printed; a second measurement step of measuring the value of the color characteristic of the recording medium on which the color material is printed; a third measurement step of measuring the value of the color characteristic of the other recording medium whose surface state differs from that of the above recording medium; and an estimate step of estimating a color obtained by printing the color material on the other recording medium whose surface state differs from that of the above recording medium by using the value of the color characteristic measured by the first to third measurement steps on the basis of a difference of the surface state between the recording medium on which the color material is printed and that of the other recording medium. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a color obtained by printing a color material on another recording medium having a different surface state, or a color obtained by printing a color material on another recording medium having a different surface state. The present invention relates to an estimation method, a color adjustment method, and a color image forming apparatus to which the color adjustment method is applied.

  In recent years, with the spread of DTP (Desk Top Publishing) and the like, the work of image editing and page imposition on computer software has become common, and full digital editing has become rare.

  In these processes, aiming for further efficiency, image setter output that directly outputs image data that has undergone page editing on film, CTP (Computer to Plate) output that directly records images on a printing plate, and printing A CTC (Computer to Cylinder) for directly recording an image on a printing plate wound on a cylinder of the machine is performed.

  Moreover, in the calibration process in such a printing process, (1) confirmation of internal errors in the work site, that is, internal school, (2) external school to be submitted to the orderer and designer for confirmation of finishing, (3) printing Proofs are created and used in three main applications: a print sample provided to the captain of the machine as a sample of the final print.

  As described above, when color printing is made, color calibration is performed at the stage of the original film, so that the Y (yellow) plate, the M (magenta) plate, the C (cyan) plate, and the BK (black) plate are obtained. Produce a proof (color proof) using each color separation net original film, and make the original printing plate, the color of the original film is correct, the color is correct, and there is no character error. The printed matter was checked in advance.

  In this case, film output or printing plate output is performed only for calibration confirmation, and printing calibration or calibration with other calibration materials has the problem that waste of film and printing plate and unnecessary work increase. .

  Therefore, in particular, in a process of creating and editing a full digital image by such a computer, a system for directly outputting a color image called DDCP (Direct Digital Color Proof) or DCP (Digital Color Proof) is required. .

  Such DDCP records digital image data processed on a computer on a plate-making film with an image setter or the like, performs a final printing operation for directly producing a printing plate with CTP, or a printing machine with CTC. Create a color proof that reproduces the output object indicated by the digital image processed on the computer before recording the image directly on the printing plate wound on the cylinder, and the design, color, text, etc. This is to confirm.

  On the other hand, based on halftone dot image data of each color separation halftone document, a silver spot color photosensitive material is exposed to a light spot composed of a combination of a plurality of lights having different wavelengths such as R, G, B, etc. There is a color proof creating apparatus that creates a color proof by reproducing each halftone image by developing the dots of basic colors Y, M, and C. In addition, the primary color (single ink color) of the printing press, the primary color (color obtained by overlaying the ink) and white (the color of the printing paper) and white (the color of the printing paper) that are obtained by overprinting the ink are reproduced. There is a type of DDCP that adjusts and outputs the output intensity of three basic colors for each of color, multi-order color, and white (for example, Patent Document 1).

  Further, in order to perform the above adjustment, it is necessary to output the primary color, the multi-order color, and white with a printing machine and measure the color to obtain the value of the color characteristic. That is, if the ink used in the printing press is Y (yellow), M (magenta), C (cyan), K (black), measurement is performed for 16 types of 1/2/3/4 color and white. It was. Further, in the case of using special colors, the measurement was performed for a total of 32 patterns including these 16 patterns and a color obtained by superimposing the respective special colors.

  By the way, there are various types of printing paper used for printing depending on the purpose and application. For example, high-quality paper composed of 100% chemical pulp, medium-quality paper and low-grade paper composed of chemical pulp and ground pulp, and one side of high-quality paper to give whiteness and smoothness to the paper Coated paper or art paper coated with clay (or a generic term for clay containing hydrous aluminum silicate as a main component) on (or both sides).

  For example, when the quality paper and the coated paper are compared here, the surface state, that is, the smoothness is different. Since the fine paper is made of chemical pulp as described above, the surface has irregularities of pulp fibers. The coated paper is coated with clay so as to eliminate the unevenness of the fine paper. Therefore, coated paper has better smoothness than fine paper, and coated paper has better so-called ink paste than fine paper. As a result, the output color differs between the printed matter output using the high quality paper by the printing machine and the printed matter printed using the coated paper due to the difference in the ink paste. In addition, art paper is similarly smoother than high-quality paper, and medium-quality paper and lower-grade paper are inferior in smoothness compared to high-quality paper.

Japanese Unexamined Patent Publication No. 2003-149996 (paragraphs [0119]-[0168], FIGS. 3 to 5)

  Therefore, in the color proof creating apparatus described in Patent Document 1, for example, in order to create a color proof of a printed matter to be printed using a coated paper with a printing machine, In order to create a color proof for a printed material to be printed using high-quality paper, even if printing is performed with 16 colors of quaternary colors and white (and 32 colors if special colors are used), the printed material Therefore, it is necessary to print and measure 16 colors of 1/2/3/4 color and white (or 32 colors if special colors are used) using high-quality paper on a printing press. there were. In other words, when printing with other printing paper having a different surface condition on the printing machine, printing is actually performed using the printing paper to be used, and re-measurement is not performed for 16 or 32 ways. Rather, a great deal of time and effort was spent on the measurement.

  In addition, many color samples distributed from ink manufacturers have printed ink on coated paper. For example, when creating a color proof for printing on high-quality paper, the color sample was measured and printed. Even when trying to grasp the ink color at that time, the color of the ink printed on different paper is not known from the measurement result of the color sample, so it is necessary to print and measure it.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to print a plurality of inks (including those printed by printing inks on a printing paper) and measure the printed inks. Based on the color characteristic value obtained in this way, the color obtained by printing ink on another printing paper having a surface state different from that of the printing paper used for the measurement or by printing a plurality of inks on top of each other is estimated. A color estimation method, a color adjustment method for reproducing a color estimated by the estimation method, and a color image forming apparatus to which the color adjustment method is applied.

  In order to achieve the above object, the invention described in claim 1 is based on the color of the color material on the recording medium on which the color material containing the pigment is printed. A color estimation method for estimating a color obtained by printing the color material on a recording medium, the first measurement step measuring a color characteristic value of the color material on the recording medium on which the color material is printed; A second measurement step of measuring a color characteristic value of the recording medium on which the color material is printed, a third measurement step of measuring a color characteristic value of another recording medium having a different surface state, Using the color characteristic values measured in the first to third measurement steps, the surface condition differs based on the difference in surface condition between the recording medium on which the color material is printed and another recording medium having a different surface condition. Estimating the color obtained by printing the color material on another recording medium It is characterized in that it comprises a floor, a.

  Further, in the invention according to claim 2, the value of the color characteristic is a spectral density with respect to each wavelength λ of light, and the first measurement step includes the color material on a recording medium on which the color material is printed. And measuring the spectral density SDW1 (λ) for each wavelength λ of the light of the recording medium on which the color material is printed, and measuring the spectral density SD1 (λ) for each wavelength λ. The third measurement step measures the spectral density SDWd (λ) for each wavelength λ of the light of another recording medium having a different surface state, and the estimation step includes the recording medium on which the color material is printed and the surface A value obtained by adjusting the difference between the spectral density SD1 (λ) and the spectral density SDW1 (λ) based on the difference in surface state with another recording medium having a different state and the spectral density SDWd (λ) are added. And the result is another recording medium having a different surface condition. It is characterized by estimating the spectral density of the color obtained by printing the color material SDM1 (lambda).

  The invention according to claim 3 further includes a preparatory step of preparing a coefficient based on a difference in surface state between a recording medium on which the color material is printed in advance and another recording medium having a different surface state, The adjustment in the estimation step is performed by multiplying the difference between the spectral density SD1 (λ) and the spectral density SDW1 (λ) by the coefficient.

  The invention according to claim 4 is characterized in that the estimating step estimates the spectral density SDM1 (λ), and further converts the spectral density SDM1 (λ) into a color system value.

  Further, the invention described in claim 5 is characterized in that the color material includes a plurality of color materials including pigments printed thereon.

  According to a sixth aspect of the present invention, the color of the color material and the second color material containing the pigment are printed on the first recording medium on which the first color material containing the pigment is printed. Based on the color of the color material on the second recording medium, the second color material is formed on the first color material on another recording medium having a surface state different from that of the first or second recording medium. A color estimation method for estimating a color obtained by overprinting and printing a color characteristic value of the first color material on the first recording medium; and A second measurement stage for measuring a color characteristic value of the first recording medium; a third measurement stage for measuring a color characteristic value of the second color material on the second recording medium; A fourth measurement step of measuring the value of the color characteristic of the second recording medium, and the value of the color characteristic of another recording medium having a different surface state Using the fifth measurement stage to be measured and the color characteristic values measured in the first to fifth measurement stages, the surfaces of the first and second recording media and the other recording media having different surface states An estimation step for estimating a color obtained by printing the second color material on the first color material on another recording medium having a different surface state based on the difference in state; and It is characterized by including.

  According to a seventh aspect of the present invention, the value of the color characteristic is a spectral density with respect to each wavelength λ of light, and the first measurement step includes the first color on the first recording medium. The spectral density SD1 (λ) for each wavelength λ of the light of the material color is measured, and the second measuring step measures the spectral density SDW1 (λ) for each wavelength λ of the light of the first recording medium. The third measurement step measures the spectral density SD2 (λ) for each wavelength λ of the light of the color of the second color material on the second recording medium, and the fourth measurement step comprises: The spectral density SDW2 (λ) for each wavelength λ of the light of the second recording medium is measured, and the fifth measuring step is the spectral density SDWd for each wavelength λ of the light of another recording medium having a different surface state. (Λ) is measured, and the estimation step includes the amount measured in the first to fifth measurement steps. Based on the difference in surface condition between the first and second recording media and the other recording medium having a different surface condition, the first color is applied to the other recording medium having a different surface condition by using light density. The spectral density SDM12 (λ) of the color obtained by printing the second color material on the material is printed and estimated.

  Further, in the invention according to claim 8, the estimation step is based on a difference in surface state between the first recording medium and another recording medium having a different surface state for each wavelength λ of the light. Based on a value obtained by adjusting a difference between the spectral density SD1 (λ) and the spectral density SDW1 (λ) and a difference in surface state between the second recording medium and another recording medium having a different surface state, A value obtained by adjusting a difference between the density SD2 (λ) and the spectral density SDW2 (λ) and the spectral density SDWd (λ) are added, and the result is estimated as the spectral density SDM12 (λ). It is said.

  According to a ninth aspect of the present invention, in the estimation step, the wavelength of each of the wavelengths λ is based on a difference in surface state between the first recording medium and another recording medium having a different surface state. The value proportional to the value obtained by adjusting the difference between the spectral density SD1 (λ) and the spectral density SDW1 (λ) and the difference in surface condition between the second recording medium and another recording medium having a different surface condition. Based on the value obtained by adjusting the difference between the spectral density SD2 (λ) and the spectral density SDW2 (λ), the spectral density SDWd (λ) is added, and the result is added to the spectral density SDM12 ( It is characterized by estimating as λ).

  Further, in the invention according to claim 10, the estimation step is based on a difference in surface state between the first recording medium and another recording medium having a different surface state for each wavelength λ of the light. The value proportional to the value obtained by adjusting the difference between the spectral density SD1 (λ) and the spectral density SDW1 (λ) and the difference in surface condition between the second recording medium and another recording medium having a different surface condition. A value proportional to the value obtained by adjusting the difference between the spectral density SD2 (λ) and the spectral density SDW2 (λ) based on this value and the spectral density SDWd (λ) are added, and the two adjusted values are further added. A value proportional to the product of the proportional values is subtracted from the addition result, and the result is estimated as the spectral density SDM12 (λ).

  The invention according to claim 11 is a preparatory stage in which each coefficient is prepared in advance based on a difference in surface condition between each of the first and second recording media and the other recording medium having a different surface condition. And the adjustment in the estimation step is performed on the difference between the spectral density SD1 (λ) and the spectral density SDW1 (λ) and the difference between the spectral density SD2 (λ) and the spectral density SDW2 (λ). This is performed by multiplying the respective coefficients.

  According to a twelfth aspect of the present invention, the estimating step estimates the spectral density SDM12 (λ), and further converts the spectral density SDM12 (λ) into a color system value.

  The invention described in claim 13 is characterized in that the first color material includes a plurality of color materials including pigments printed thereon.

  According to a fourteenth aspect of the present invention, the halftone image of the color material has a surface state different from that of the recording medium based on the color of the color material on the recording medium on which the color material containing the pigment is printed. A color adjustment method for performing color adjustment by changing the output intensity of a plurality of basic colors so as to reproduce the color of a halftone image portion obtained by printing on another recording medium as a target color, A storage step for storing in advance a reference table indicating a correspondence relationship between the output intensity of the basic color and the value of the L * a * b * color system, the color material on the recording medium on which the color material is printed, Using the color characteristic values of the recording medium on which the color material is printed and the other recording medium having a different surface state, the surface state of the recording medium on which the color material is printed and the other recording medium having a different surface state On the other recording medium having a different surface state based on the difference in An estimation stage for estimating the L * a * b * color system value of the color obtained by printing the material, the L * a * b * color system value obtained in the estimation stage, and the reference table Generating a color channel table by obtaining a combination of output intensities of the plurality of basic colors for reproducing the target color, and based on the color channel table, the plurality of basic colors The color adjustment is performed by changing the output intensity.

  In the invention according to claim 15, the value of the color characteristic is a spectral density with respect to each wavelength λ of light, and the estimation step includes the color material and the color on the recording medium on which the color material is printed. Using spectral density SD1 (λ), spectral density SDW1 (λ), and spectral density SDWd (λ) as spectral densities of the recording medium on which the material is printed and the other recording mediums having different surface states, A value obtained by adjusting a difference between the spectral density SD1 (λ) and the spectral density SDW1 (λ) based on a difference in surface condition between the recording medium on which the color material is printed and another recording medium having a different surface condition; The spectral density SDWd (λ) is added, and the result is estimated as the spectral density SDM1 (λ) of the color obtained by printing the color material on the other recording medium having a different surface state. Spectral density SDM1 (λ) is L * a b * it is characterized by converting the value of the color system.

  The invention according to claim 16 further includes a preparatory step of preparing a coefficient based on a difference in surface state between a recording medium on which the color material is printed in advance and another recording medium having a different surface state, The adjustment in the estimation step is performed by multiplying the difference between the spectral density SD1 (λ) and the spectral density SDW1 (λ) by the coefficient.

  The invention described in claim 17 is characterized in that the color material includes a plurality of color materials including pigments printed thereon.

  In the invention according to claim 18, the color of the color material and the second color material containing the pigment are printed on the first recording medium on which the first color material containing the pigment is printed. Based on the color of the color material on the second recording medium, the halftone image of the first and second color materials is placed on another recording medium having a surface state different from that of the first and second recording media. A color adjustment method for performing color adjustment by changing the output intensity of a plurality of basic colors so as to reproduce the color of a halftone line portion obtained by printing as a target color, the output intensity of the plurality of basic colors And a storage step for storing in advance a reference table indicating the correspondence between L * a * b * color system values, the first color material on the first recording medium, and the first recording Medium, second color material on second recording medium, second recording medium, and surface state Using the value of the color characteristic of another different recording medium, another recording having a different surface condition is performed based on the difference in surface condition between the first and second recording media and the other recording medium having a different surface condition. An estimation step of estimating a value of an L * a * b * color system of a color obtained by printing the second color material on the first color material over the medium; and the estimation step A color channel table is generated by obtaining a combination of output intensities of the plurality of basic colors for reproducing the target color based on the values of the L * a * b * color system obtained in step 1 and the reference table. And a color adjustment is performed by changing output intensities of the plurality of basic colors based on the color channel table.

  Further, in the invention described in claim 19, the value of the color characteristic is a spectral density with respect to each wavelength λ of light, and the estimation step includes the first color material on the first recording medium, Spectral density SD1 (as the spectral density of each of the first recording medium, the second color material on the second recording medium, the second recording medium, and another recording medium having a different surface state. λ), spectral density SDW1 (λ), spectral density SD2 (λ), spectral density SDW2 (λ), and spectral density SDWd (λ) are used, and the surface state differs from the first and second recording media. A color obtained by printing the second color material over the first color material on another recording medium having a different surface state based on a difference in surface state with another recording medium Of the spectral density SDM12 (λ) of The (lambda) is characterized by converting the value of the L * a * b * color system.

  Further, in the invention according to claim 20, the estimation step is based on a difference in surface state between the first recording medium and another recording medium having a different surface state for each wavelength λ of the light. Based on a value obtained by adjusting a difference between the spectral density SD1 (λ) and the spectral density SDW1 (λ) and a difference in surface state between the second recording medium and another recording medium having a different surface state, A value obtained by adjusting a difference between the density SD2 (λ) and the spectral density SDW2 (λ) and the spectral density SDWd (λ) are added, and the result is estimated as the spectral density SDM12 (λ). It is said.

  Further, in the invention according to claim 21, in the estimation step, based on a difference in surface state between the first recording medium and another recording medium having a different surface state, for each wavelength λ of the light. The value proportional to the value obtained by adjusting the difference between the spectral density SD1 (λ) and the spectral density SDW1 (λ) and the difference in surface condition between the second recording medium and another recording medium having a different surface condition. Based on the value obtained by adjusting the difference between the spectral density SD2 (λ) and the spectral density SDW2 (λ), the spectral density SDWd (λ) is added, and the result is added to the spectral density SDM12 ( It is characterized by estimating as λ).

  According to a twenty-second aspect of the present invention, in the estimation step, the wavelength of each of the wavelengths λ is based on a difference in surface state between the first recording medium and another recording medium having a different surface state. The value proportional to the value obtained by adjusting the difference between the spectral density SD1 (λ) and the spectral density SDW1 (λ) and the difference in surface condition between the second recording medium and another recording medium having a different surface condition. A value proportional to the value obtained by adjusting the difference between the spectral density SD2 (λ) and the spectral density SDW2 (λ) based on this value and the spectral density SDWd (λ) are added, and the two adjusted values are further added. A value proportional to the product of the proportional values is subtracted from the addition result, and the result is estimated as the spectral density SDM12 (λ).

  The invention according to claim 23 is a preparatory stage in which each coefficient is prepared in advance based on a difference in surface condition between each of the first and second recording media and the other recording medium having a different surface condition. And the adjustment in the estimation step is performed on the difference between the spectral density SD1 (λ) and the spectral density SDW1 (λ) and the difference between the spectral density SD2 (λ) and the spectral density SDW2 (λ). This is performed by multiplying the respective coefficients.

  According to a twenty-fourth aspect of the present invention, the first color material includes a plurality of color materials including a pigment printed on each other.

  According to a twenty-fifth aspect of the invention, a halftone image of the color material has a surface state different from that of the recording medium based on the color of the color material on a recording medium on which a color material containing a pigment is printed. A color image forming apparatus that forms a color image while reproducing and changing the output intensity of a plurality of basic colors using a color of a halftone dot line portion obtained by printing on another recording medium as a target color, A reference table showing the correspondence between the output intensity of a plurality of basic colors and the values of the L * a * b * color system, the color material on the recording medium on which the color material is printed, and the color material are printed And the color characteristics of other recording media having different surface conditions, and based on the difference in surface condition between the recording medium on which the color material is printed and the other recording medium having different surface conditions. The color material is printed on another recording medium having a different surface state. The target is obtained by estimating the value of the L * a * b * color system of the color obtained in this way, the value of the L * a * b * color system obtained by the estimation unit and the reference table. Generating means for obtaining a combination of output intensities of the plurality of basic colors for reproducing the color to be a color channel table, and when forming the color image, based on the color channel table, the plurality of the plurality of basic colors And control means for controlling to change the output intensity of the basic color.

  According to a twenty-sixth aspect of the present invention, the color of the color material and the second color material containing the pigment are printed on the first recording medium on which the first color material containing the pigment is printed. Based on the color of the color material on the second recording medium, the halftone image of the first and second color materials is placed on another recording medium having a surface state different from that of the first and second recording media. A color image forming apparatus for forming a color image while reproducing and changing the output intensity of a plurality of basic colors using a color of a halftone line portion obtained by printing as a target color, and outputting the plurality of basic colors A reference table showing the correspondence between the intensity and the value of the L * a * b * color system, the first color material on the first recording medium, the first recording medium, the second The second color material on the recording medium, the second recording medium, and others having different surface states Based on the difference in surface condition between the first and second recording media and the other recording medium having a different surface condition, the value of the color characteristic of the recording medium is used. An estimation means for estimating an L * a * b * color system value of a color obtained by printing the second color material on the first color material; Generating means for generating a color channel table by obtaining a combination of output intensities of the plurality of basic colors for reproducing the target color based on the values of the L * a * b * color system and the reference table; And control means for controlling the output intensity of the plurality of basic colors based on the color channel table when forming the color image.

  According to the color estimation method of claim 1, the ink printed on the printing paper, the value of the color characteristic of the printing paper, and the value of the color characteristic of another printing paper having a different surface state from the printing paper are used. Based on the difference in the surface state of the printing paper, the color obtained by printing the ink on another printing paper having a different surface state can be estimated.

  According to the color estimation method of claim 2, the ink printed on the printing paper, the spectral density of the printing paper, and the spectral density of another printing paper having a different surface state from the printing paper are used. Based on the difference in surface condition, it is possible to estimate the color obtained by printing the ink on another printing paper having a different surface condition.

  The color estimation method according to claim 6, wherein the first ink printed on the first printing paper, the first printing paper, the second ink printed on the second printing paper, and the second printing. Using the value of the color characteristic of the paper and the value of the color characteristic of the other print paper having a different surface state from the first or second print paper, the surface state It is possible to estimate the color obtained by printing the second ink on the first ink on another different printing paper.

  The color estimation method according to claim 7, wherein the first ink printed on the first printing paper, the first printing paper, the second ink printed on the second printing paper, and the second printing. Using the spectral density of the paper and the spectral density of another printing paper having a surface state different from that of the first or second printing paper, another printing having a different surface state is performed based on the difference in the surface state of the printing paper. It is possible to estimate a color obtained by printing the second ink on the first ink.

  15. The color adjustment method according to claim 14, wherein the ink printed on the printing paper, the value of the color characteristic of the printing paper, and the value of the color characteristic of another printing paper having a different surface state from the printing paper are used. Based on the difference in the surface condition of the printing paper, the color obtained by printing the ink on the other printing paper with the different surface condition is estimated, and the estimated color is reproduced using a plurality of basic colors as targets. You can make color adjustments.

  According to the color adjustment method of claim 15, the ink printed on the printing paper, the spectral density of the printing paper, and the spectral density of another printing paper having a surface state different from the printing paper are used. Based on the difference in surface condition, the color obtained by printing the ink on another printing paper having a different surface condition is estimated, and the estimated color is reproduced using a plurality of basic colors as targets. Adjustments can be made.

  The color adjustment method according to claim 18, wherein the first ink printed on the first printing paper, the first printing paper, the second ink printed on the second printing paper, and the second printing. Using the value of the color characteristic of the paper and the value of the color characteristic of the other print paper having a different surface state from the first or second print paper, the surface state The color obtained by printing the second ink on the first ink on another different printing paper is estimated, and the color is reproduced using a plurality of basic colors with the estimated color as a target. Adjustments can be made.

  The color adjustment method according to claim 19, wherein the first ink printed on the first printing paper, the first printing paper, the second ink printed on the second printing paper, and the second printing. Using the spectral density of the paper and the spectral density of another printing paper having a surface state different from that of the first or second printing paper, another printing having a different surface state is performed based on the difference in the surface state of the printing paper. Estimating a color obtained by printing the second ink on the first ink on a sheet of paper, and performing color adjustment so that the estimated color is reproduced using a plurality of basic colors. Can do.

  According to the color image forming apparatus of claim 25, the ink printed on the printing paper, the value of the color characteristic of the printing paper, and the value of the color characteristic of another printing paper having a different surface state from the printing paper are obtained. Use, based on the difference in the surface condition of the printing paper, estimate the color obtained by printing the ink on another printing paper with the different surface condition, and use a plurality of basic colors with the estimated color as a target Color adjustments can be made to reproduce.

  The color image forming apparatus according to claim 26, wherein the first ink printed on the first printing paper, the first printing paper, the second ink printed on the second printing paper, the second Using the value of the color characteristic of the printing paper and the value of the color characteristic of the other printing paper having a different surface state from the first or second printing paper, the surface state is determined based on the difference in the surface state of the printing paper. A color obtained by printing the second ink on the first ink on another printing paper having a different color is estimated, and the estimated color is reproduced using a plurality of basic colors as targets. Color adjustment can be performed.

  In the present invention, a plurality of inks are printed on a printing paper as a recording medium (including those printed by overprinting inks), and the measurement is performed based on the values of color characteristics obtained by measuring the printed inks. The printing paper used in the above is to estimate the color obtained by printing ink on another printing paper having a different surface state or printing a plurality of inks on top of each other.

  In addition, a description will be given of a method using a transmission density (hereinafter referred to as a spectral density) with respect to each wavelength λ of light as a value of color characteristics measured and used in the color estimation method.

Here, the spectral density is, for example, the reflectance R is measured by changing the wavelength every 10 nm between 380 nm and 730 nm,
-0.5 × LOG ₁₀ (R)
It is converted into a density by the formula of

  The value of the L * a * b * color system is one of the values of the color system representing the color, and represents the color in the three-dimensional space of the L * axis, a * axis, and b * axis. The hue and saturation are represented by the a * b * plane, and L * is a value of a color characteristic that is orthogonal to the a * b * plane and represents the lightness. The values of the L * a * b * color system are x-bar, y-bar defined by the CIE (Commission Internationale de l'Eclairage) as equivalent to the sensitivity of the human eye. , Z-bar spectral characteristics (predetermined spectral characteristics) based on the values of the XYZ color system obtained by integrating the amount of light.

  Hereinafter, in describing the color estimation method and the color adjustment method of the present invention, an embodiment applied to a color proof creating apparatus (color image forming apparatus) will be described as an example, and will be specifically described with reference to the drawings.

(Control configuration of color proofing device)
First, the color proof creating apparatus according to the present embodiment prints halftone dot images of a plurality of inks (C (cyan), M (magenta), Y (yellow), K (black), and special colors)) with a printing press. The color of the halftone image portion obtained by superimposing is set as a target color, and the target color is set to a plurality of basic colors (Y, M, C, hereinafter “C, M, Y”, “YMC” in the color proof creating apparatus). ”,“ CMY ”, etc. may be written in different orders.) And output a color image while changing the output intensity and apply the color adjustment method using the color estimation method of the present invention. Therefore, it is suitable.

  FIG. 1 shows a functional block diagram of the color proof producing apparatus. As shown in FIG. 1, the color proof creating apparatus according to the present embodiment includes a control unit 1, a color calculation unit 2, a color channel creation unit 3, and an image recording unit 4. Further, details of each part will be described below.

  The color calculation unit 2 includes a color calculation unit 21, a color characteristic table 22, a coefficient table 23, a color table 24, and an input unit 25.

  The color characteristic table 22 includes the CMYK1 / 2/3/4 color and the printing paper A that are printed on the printing paper A using, for example, C, M, Y, and K inks as the values of the color characteristics. The spectral density of the ground color, for example, the color obtained by printing the special color on the printing paper B, the spectral density of the ground color of the printing paper B, and the spectral density of the printing paper having different surface conditions, such as the ground colors of C, D. Stored.

  Here, CMYK1 / 2/3/4 quaternary colors will be described. A primary color is a color in CMYK, a secondary color is a color that combines two of CMYK, a tertiary color is a color that combines three of CMYK, and a quaternary color C, M, Y, K, R (M + Y), G (C + Y), B (C + M),..., C + M + Y + K, which is a combination of four of CMYK.

  Further, FIG. 2 shows the configuration of the color characteristic table 22. As shown in FIG. 2, each color is composed of the above-described colors and their spectral densities. However, each numerical value is omitted.

  The coefficient table 23 includes a transparency coefficient a, a trapping ratio coefficient b, an overprint correction coefficient c, and an inter-sheet density adjustment coefficient r (coefficient based on the difference in the recording medium of the present invention) used for color estimation described later. For example, each spot color is stored in a configuration as shown in FIG. However, the inter-paper density adjustment coefficient r may be stored in a separate table as a coefficient related to the paper without corresponding to the ink. The transparency coefficient a is a coefficient for correcting the spectral density (transmission density) of the lower color when a spot color is overprinted, and the trapping rate coefficient b is a value when the spot color is printed on the printing paper. It is a coefficient for correcting a difference in spectral density (transmission density) generated from a difference in so-called ink paste when overprinted on ink. The overprint correction coefficient c is a coefficient used for a correction term included in an expression used in color estimation described later. The inter-paper density adjustment coefficient r is used to adjust the difference in density caused by the difference in ink on the printing paper to be printed.

  If the ink 2 is completely transparent, the transparency coefficient a is “1”. If the ink 2 is completely opaque, the transparency coefficient a is “0”, so the transparency coefficient a is a constant between 0 and 1. It is. In addition, since the ink paste is generally lower when printing on other ink than when printing on printing paper, the trapping rate coefficient b is a constant between 0 and 1. It is.

  The input means 25 is for, for example, designating ink (C, M, Y, K and special colors) used for printing and printing paper and inputting an instruction for creating a color proof. Further, the color characteristic table 22 is used to input the above-described colors and their spectral densities, and the coefficient table 23 is used to input each coefficient. In addition, for example, it is an interface for connecting to a measuring instrument, a reading device for mounting a FD (Floppy (Registered Trademark) Disk) or the like into which spectral density measurement results and coefficients are input so as to be able to be put in and out. May be.

  Further, the color characteristic table 22 and the coefficient table 23 may be incorporated from the beginning in an HDD (Hard Disk Drive) provided in the color proof creating apparatus, for example.

  The color calculation means 21 is an estimation means of the present invention for obtaining the value of each L * a * b * color system from the value of each color characteristic (spectral density in the present embodiment) stored in the color characteristic table 22. , The function stored in the color table 24, the color when printing on different printing paper and the spectral density when overprinting are estimated from each spectral density, and L * a * from the estimated spectral density A function as an estimation means of the present invention for obtaining the value of the b * color system and a function of storing the obtained L * a * b * color system value in the color table 24 are provided. A detailed calculation method will be described later.

  The color table 24 includes L * a * b of the above-described CMYK1 / 2/3/4 color, special color single color, the color obtained by printing the special color on each of the CMYK1 / 2/3/4 color and the ground color of the printing paper. * The color system values are stored in the configuration as shown in FIG. FIG. 4 also shows an example of the L * a * b * color system values of the above-mentioned CMYK1 / 2/3/4 color and the background color of the printing paper (displayed as W (white) in the figure). The values related to the spot colors are omitted.

  The color channel creation unit 3 includes a color channel calculation unit 31, a reference table 32, and a color channel table 33.

  The reference table 32 defines an L * a * b → CMY LUT that defines a correlation with an output intensity combination of each basic color corresponding to an L * a * b * color system value as an output characteristic in the image recording unit 4. Is stored. This L * a * b → CMY LUT is a plurality of colors in which C, M, and Y output intensities of the image recording unit 4 to be described later are equally divided from a minimum value 0 to a maximum value and the outputs are combined. A color chart in which the images are arranged is output, the L * a * b * color system values of the plurality of color images are measured, and the combination of the C, M, and Y output intensities at that time and the L * a * From the value of the b * color system, it can be determined by the method described in the specification of Japanese Patent Application No. 2002-064629 by the present applicant.

  The color channel calculation unit 31 has a function as a generation unit of the present invention, and includes CMYK1 / 2/3/4 color, spot color single color, and CMYK1 / 2/3/4 color stored in the color table 24. Image recording is performed using the L * a * b * color system values of the overprinted spot colors and the ground color of the printing paper, and the L * a * b → CMY LUT stored in the reference table 32. The unit 4 obtains a combination of CMY output intensities for outputting the respective L * a * b * color system values and stores them in the color channel table 33. Note that the method for obtaining the combination of CMY output intensities using the values of the L * a * b * color system as input values is the method described in the specification of Japanese Patent Application No. 2002-064629 by the present applicant. Can be used.

  Further, in the present embodiment, it has been described that L * a * b → CMY LUT is stored as the reference table 32. However, as the reference table 32, L * a * b * corresponding to combinations of output intensities of the respective basic colors. A CMY → L * a * b LUT in which a correlation with a color system value is defined may be stored. In that case, when obtaining a combination of CMY output intensities for outputting L * a * b * color system values, CMY → L * a * b LUT to L * a * b → CMY LUT Find it. Therefore, as the “reference table” of the present invention, the output intensity of a plurality of basic colors such as L * a * b → CMY LUT and CMY → L * a * b LUT and values of the L * a * b * color system It is sufficient if it shows the correspondence between the two.

  The color channel table 33 is an image record corresponding to the above-described CMYK1 / 2/3/4 color, special color single color, CMYK1 / 2/3/4 color and the background color of the printing paper. A combination of CMY output intensities in the unit 4 is stored in a configuration as shown in FIG. FIG. 5 shows an example of a combination of the output intensity of the CMYK1 / 2/3/4 color and the white background (shown as W (white) in the figure) from the minimum value 0 to the maximum value. The output intensities of 140, M, and C are shown as the minimum value 0 to the maximum value 160, and the values related to the spot color are different depending on the type of the spot color, and are not shown.

  The image recording unit 4 sensitizes the magenta coloring layer (M layer) of the photosensitive material with red (R) light, and sensitizes the cyan coloring layer (C layer) of the photosensitive material with green (G) light. The yellow color developing layer (Y layer) of the photosensitive material is exposed to light, and development processing is performed to reveal and output basic colors Y, M, and C, thereby forming a color image. The photosensitivity by the red (R) light, the green (G) light, and the blue (B) light is performed by simultaneously irradiating light of these colors for each pixel in a dot-sequential manner.

  The control unit 1 has a function of controlling each unit and a function as a control unit of the present invention, and is a halftone dot separated for each ink of C, M, Y, K, and special color from image data. Based on the image data, the colors to be output by each pixel in the image storage unit 4 are the above-mentioned CMYK1 / 2/3/4 quaternary color, special color single color, and CMYK1 / 2/3/4 quaternary color. It is determined whether the printed color or the ground color of the printing paper is obtained, a combination of CMY output intensities is obtained with reference to the color channel table 33, and the basic colors Y, M, The Y, M, and C output intensity data obtained from the color channel table 33 are converted into B, R, and G exposure output intensity data so that the C output intensity is changed, and the image recording unit 4 Control to change the intensity of light of each color. In order to realize such functions, a CPU (not shown), a program for performing overall control, a program for changing the output intensity of Y, M, and C, and various data necessary for executing each program are stored. A system memory (not shown) that constitutes a work area for storing and executing each program is configured.

  In this way, the color proof making apparatus changes the output intensity of the basic colors Y, M, and C, and prints the halftone image of each ink of C, M, Y, K, and special colors on the printing press. Create a color proof by reproducing the colors that are created.

(Color estimation method)
Next, the color estimation method of the present invention will be described. For easy understanding, each step of the color estimation method will be described first, and an example in which a color adjustment method including the color estimation method is applied to a color proof creating apparatus will be described later.

  FIG. 6 is a flowchart showing the procedure of the color estimation method of the present invention. The color estimation method of the present embodiment will be described with reference to FIG. Hereinafter, each step will be omitted if it is step S11 in FIG. The other steps are the same.

(S11)
First, the lower ink (first color material) (hereinafter referred to as ink 1) is printed on the printing paper A (first recording medium) when overprinting, and the color of the printed ink (hereinafter referred to as ink 1). , Color 1) and the ground density of the printing paper A (hereinafter referred to as color W1) are measured. Here, the spectral density as the value of the color characteristic of color 1 is SD1 (λ), and the spectral density of color W1 is SDW1 (λ). The ink 1 corresponds to one of the CMYK1 / 2/3/4 quaternary colors printed using the above-described C, M, Y, and K inks. The spectral density is obtained by measuring the reflectance at each wavelength as described above and converting the reflectance. The same applies to the spectral density measurement performed below.

(S12)
Next, the upper ink (second color material) (hereinafter referred to as ink 2) when printed is printed on the printing paper B (second recording medium), and the color of the printed ink (hereinafter referred to as ink 2). , Color 2) and the background density of the printing paper B (hereinafter referred to as color W2) are measured. Here, the spectral density of color 2 is SD2 (λ), and the spectral density of color W2 is SDW2 (λ). This ink 2 is equivalent to what was printed using the above-mentioned special color ink. Further, the printing paper A may be used in place of the printing paper B.

(S13)
Further, the spectral density of the ground color (hereinafter referred to as color Wd) of the printing paper C having a surface state different from that of the printing paper A or B is measured. Here, the spectral density of the color Wd is SDWd (λ).

  Here, the difference in the surface state will be described. For example, there are various types of printing paper used for printing depending on the purpose and application. For example, high-quality paper composed of 100% chemical pulp, medium-quality paper and low-grade paper composed of chemical pulp and ground pulp, and one side of high-quality paper to give whiteness and smoothness to the paper Coated paper or art paper coated with clay (or both sides). For example, since high-quality paper is made of chemical pulp, the surface thereof has irregularities of pulp fibers, and the coated paper is coated with clay so as to eliminate the irregularities of high-quality paper. Accordingly, the surface of the coated paper is smoother than the surface of the high quality paper, and the coated paper has better so-called ink paste than the high quality paper. The difference in the surface state of the present embodiment is a difference that causes a difference in ink paste, and may be referred to as, for example, the above-described difference in smoothness.

(S14)
Then, the color obtained by printing the ink 1 on the printing paper C (hereinafter referred to as color M1), the color obtained by printing the ink 2 on the printing paper C (hereinafter referred to as color M2), and the printing paper C A color obtained by printing ink 2 on ink 1 (hereinafter referred to as color M12) is estimated. Here, the spectral density of the color M1 is SDM1 (λ), the spectral density of the color M2 is SDM2 (λ), and the spectral density of the color M12 is SDM12 (λ).

First, let SDM1 (λ) be
SDM1 (λ) = r1 × (SD1 (λ) −SDW1 (λ)) + SDWd (λ)
Asking. That is, the spectral density SDW1 (λ) of the printing paper A is eliminated by subtracting SDW1 (λ) from SD1 (λ), and the spectral density of the ink 1 itself when printing on the printing paper A is obtained. Further, since the spectral density of the ink 1 itself when printing on the printing paper C changes due to the difference in the ink paste due to the difference in the surface condition between the printing paper A and the printing paper C, the difference in the glue due to the difference in the surface condition. Is adjusted by multiplying the inter-paper density adjustment coefficient r according to r1 to be the spectral density of the ink 1 itself when printing on the printing paper C, and instead of the spectral density SDW1 (λ) of the excluded printing paper A, the printing paper By adding the spectral density SDWd (λ) of C, the spectral density of the color M1 obtained by printing the ink 1 on the printing paper C is obtained.

Similarly, the spectral density of color M2 is SDM2 (λ),
SDM2 (λ) = r2 × (SD2 (λ) −SDW2 (λ)) + SDWd (λ)
Asking.

  Here, r1 and r2 are, for example, printing papers A and B that have a smooth surface condition such as coated paper, and printing paper C that is high-quality paper and has a poor surface condition and smoothness compared to coated paper. In this case, since the ink paste is deteriorated, the numerical value is smaller than 1 so that the spectral density becomes small. Conversely, if the printing papers A and B are high-quality paper and the printing paper C is coated paper, It becomes a numerical value larger than 1. Needless to say, if the same paper is used, the ink paste does not change, so 1 may be used. In other words, this is the same as not performing the adjustment using the inter-paper density adjustment coefficient r.

  The SDM1 (λ) may be a spectral density obtained by overlapping a plurality of inks such as CMYK 2/3/4 color as well as a single ink.

Next, the spectral density SDM12 (λ) of the color M12 is estimated. First, when correction by a coefficient as described in the coefficient table 23 is not required,
SDM12 (λ) = r1 × (SD1 (λ) −SDW1 (λ)) + r2 × (SD2 (λ) −SDW2 (λ)) + SDWd (λ)
Asking. That is, by adding the spectral density of the ink 1 itself when printing on the printing paper C, the spectral density of the ink 2 itself when printing on the printing paper C, and the spectral density SDWd (λ) of the printing paper C, the printing paper The spectral density of the color M12 obtained by printing the ink 1 on the ink 1 and the ink 2 is printed. In this case, the ink 2 is not on the surface of the printing paper C with the printing paper C interposed between the printing paper C, but the ink 1 is affected by the surface condition of the printing paper C, and the ink 2 Ink adhesion to the ink 1 becomes worse. In the present embodiment, the spectral density of the ink 2 itself when printing on the printing paper C is adjusted by multiplying the density adjustment coefficient r2 between papers according to the difference in ink paste due to the difference in printing paper.

In addition, when it is necessary to correct the transparency coefficient a and the wrapping rate coefficient b,
SDM12 (λ) = a × r1 × (SD1 (λ) −SDW1 (λ)) + b × r2 × (SD2 (λ) −SDW2 (λ)) + SDWd (λ)
Asking.

  That is, the first term a × r1 × (SD1 (λ) −SDW1 (λ)) indicates the spectral density of the ink 1 itself when printing on the printing paper C obtained through the ink 2. First, by subtracting SDW1 (λ) from SD1 (λ), the spectral density of ink 1 itself excluding the spectral density SDW1 (λ) of printing paper A is obtained, and printing is performed by multiplying the density adjustment coefficient r1 between papers. The spectral density of the ink 1 itself when printing on the printing paper C obtained through the ink 2 is obtained by performing adjustment according to the difference in the paper and further multiplying the transparency of the ink 2 as the transparency coefficient a. .

  The second term b × r2 × (SD2 (λ) −SDW2 (λ)) indicates the spectral density of the ink 2 itself overlaid on the other ink when printing on the printing paper C. First, by subtracting SDW2 (λ) from SD2 (λ), the spectral density of ink 2 itself excluding the spectral density SDW2 (λ) of printing paper B is obtained, and printing is performed by multiplying the density adjustment coefficient r2 between papers. Print on printing paper C by making adjustments according to the paper difference and multiplying the so-called ink paste difference between printing on printing paper and other ink as the trapping rate coefficient b This is the spectral density of the ink 2 itself that overlaps the ink 1.

  Then, as the third term, the spectral density SDWd (λ) of the printing paper C is added to obtain the spectral density of the color M12 obtained by printing the ink 2 on the printing paper C and printing the ink 2 thereon.

Furthermore, the spectral density obtained by the sum of the above three terms at the wavelength at which the spectral density of the ink 1 itself or the spectral density of the ink 2 itself is relatively high is larger than the actual measured value of overprinting. If you need to correct it,
SDM12 (λ) = a × r1 × (SD1 (λ) −SDW1 (λ)) + b × r2 × (SD2 (λ) −SDW2 (λ)) + SDWd (λ) −c × a × r1 × (SD1 (λ ) -SDW1 (λ)) × b × r2 × (SD2 (λ) −SDW2 (λ))
That is, the fourth term c × a × r1 × (SD1 (λ) −SDW1 (λ)) × b × r2 × (SD2 (λ) −SDW2 (λ)) is subtracted from the sum of the three terms. The fourth term is a correction term for calculating a correction value for overprinting. The spectral density of ink 1 itself when printing on printing paper C or the spectral density of ink 2 itself when printing on printing paper C is the fourth term. A × r1 × (SD1 (λ) −SDW1 (λ)) and b × r2 × (SD2 (λ) −SDW2 (λ)) are corrected so as to increase the value to be reduced when the density is relatively high. The product is multiplied by the overprint correction coefficient c. In other words, the value is proportional to the product of (SD1 (λ) −SDW1 (λ)) and (SD2 (λ) −SDW2 (λ)).

  In this way, the color (color M1) obtained by printing the ink 1 on the printing paper C having a different surface state, the color (color M2) obtained by printing the ink 2, and the ink 1 obtained by printing the ink 2 on top of each other. Each spectral density of the color (color M12) to be obtained can be estimated, and furthermore, the value of the color system such as the XYZ color system or the L * a * b * color system may be obtained by converting from the spectral density.

In the above description, the colors of the printing papers A, B, and C are different, but if the colors are the same and only the smoothness is different,
SDW1 (λ) = SDW2 (λ) = SDWd (λ)
Can be treated as. In that case, the spectral density may be measured for any one of them. Of course, if any two papers have the same color, the two may be treated as equal.

  Further, the coefficient values a, b, and c are obtained by measuring each spectral density SD for a plurality of colors overprinted with ink in advance so that the difference between the measured spectral density and the estimated spectral density is minimized. You can ask for it. In addition, the inter-paper density adjustment coefficient r measures the spectral density SD for each color printed with ink on a printing paper having a different surface state, and the difference between the measured spectral density and the estimated spectral density for that color is the smallest. You just have to ask for it.

(Color adjustment method in color proof making device)
Next, a processing procedure in the color proof creation apparatus of the present embodiment to which the color adjustment method including the color estimation method described above is applied will be described with reference to the flowchart shown in FIG. Here, the transparency coefficient a, the trapping rate coefficient b, the overprint correction coefficient c, and the inter-paper coefficient r are stored in advance in the coefficient table 23. In addition, the CMYK1 / 2/3/4 color and the background color spectral density of the printing paper A printed on the printing paper A using the C, M, Y, and K inks on the printing paper A, and the special color on the printing paper B Are measured in advance, and the spectral density of the ground color of the printing papers C, D... With different surface states is measured in advance and stored in the color characteristic table 22.

(S21)
As shown in FIG. 7, first, an instruction to create a color proof in which ink (C, M, Y, K, and special colors) used for printing using the input means 25 performed by the operator and printing paper is designated. Accept.

(S22)
In response to the input of the instruction, the color calculation means 21 refers to the color characteristic table 22 and prints CMYK1 / 2/3 printed on the printing paper A by using each color ink of C, M, Y, K with the printing press. / Spectral density SD1 and SDW1 of the quaternary color (color 1) and the background color (color W1) of the printing paper A, a color (color 2) obtained by printing a special color on the printing paper B, and a ground color (color W2) of the printing paper B Are extracted, and the spectral density SDWd of the ground color (color Wd) of the printing paper (printing paper C) to be used is extracted. Further, these spectral densities may be input from the input means 25, and the color calculation means 21 may act so as to accept the input spectral density.

(S23)
Further, the color calculation means 21 calculates the spectral density SDM1 (λ) of each color obtained by printing the CMYK1 / 2/3/4 color on the printing paper C using the above-described calculation formula. Further, the spectral density SDM2 (λ) of the color obtained by printing the special color on the printing paper C is calculated using the above-described arithmetic expression.

  Then, the above spectral expression (one of the three expressions shown for SDM12) is used for each spectral density SDM12 when printing on the printing paper C by printing the special colors on the CMYK1 / 2/3/4 colors. Use to calculate. When using each coefficient, the color calculation means 21 refers to the coefficient table 23.

  Then, each spectral density is converted from each spectral density SDM1 (λ), spectral density SDM2 (λ), and spectral density SDM12 (λ), and a value of the L * a * b * color system is obtained to obtain a color table. 24.

(S24)
Next, the color channel calculation means 31 calculates the white background, CMYK1 / 2/3 from the L * a * b * color system value stored in the color table 24 and the L * a * b → CMY LUT of the reference table 32. A combination of output intensities of a plurality of basic colors is obtained and stored in the color channel table 33 for all the colors obtained by overprinting the / quaternary color, the spot color, and the spot color on the CMYK1 / 2/3/4 quaternary color.

(S25)
Then, the control unit 1 refers to the color channel table 33 and controls the image recording unit 4 so as to change the combination of the output intensities of a plurality of basic colors based on the image data, and the image recording unit 4 follows the control. Perform image formation.

  In this way, color estimation is performed when printing is performed using another printing paper having a different surface condition, and color adjustment of the color image is performed, so that C, M, Y can be applied to another printing paper having a different surface condition by the printing press. When creating a color proof by aiming at the color created by overprinting halftone dot images of each of the inks of K, K, and special colors, the color is measured by printing on other printing papers with different surface conditions. There is no need. Therefore, the working time can be shortened. Also, if there is a color sample on which ink is printed, the color can be estimated by measuring the color sample even when printing on another printing paper having a surface state different from that of the color sample.

  In addition, when a characteristic having different characteristics is used for the transparency coefficient a, the trapping ratio coefficient b, and the overprint correction coefficient c, the coefficients are stored in the coefficient table 23 for each type as shown in FIG. In addition, when the spectral density SD2 (λ) of the ink 2 is input, the spectral density SDM (λ) may be obtained by selecting the type.

  Further, the above color estimation or color channel table generation is performed using an information processing device such as a PC (Personal Computer), and the color estimation result or the color channel table is transmitted to a color proof via a medium such as a floppy disk. It is also possible for the creation device to acquire and use it for forming a color image.

  Further, in an image output system comprising an information processing device such as a PC and a color proof creating device, the information processing device such as a PC has the above-described color estimation or color channel table generation function, and the color estimation result or color channel table is provided. It is also possible for the color proof making apparatus to acquire the image via the interface and use it for forming a color image.

  Next, a specific example is shown in which the color obtained by printing on another printing paper having a different surface state is estimated using the color estimation method of the present embodiment. In this example, magenta (M) is used as ink 1, high-quality paper is printed on printing paper A on which magenta is printed, special paper (red) is used as ink 2, and coated paper is used as printing paper B on which special color (red) is printed. As an example, a case where high-quality paper is used as the printing paper C having a different surface condition (in this example, the printing paper C having a different surface condition for estimating the color is the same as the printing paper A printed with magenta is used. Explain to example).

  First, the spectral reflectance R is measured. The measurement results are shown in FIG. Here, the spectral reflectance of color 1 (magenta (M) printed on printing paper A) is R1 (λ), the spectral reflectance of color W1 (printing paper A printed with magenta) is RW1 (λ), and color 2 Spectral reflectance of (special color (red) printed on printing paper B) is R2 (λ), spectral reflectance of color W2 (printing paper B printed with special color (red)) is RW2 (λ), color Wd (surface The spectral reflectance of the printing paper C) in different states is assumed to be RWd (λ) (which is the same because it uses the above-described arithmetic expression, but is the same because it is the same). In addition, in FIG. 8, the result measured about the wavelength of 10 nm increments between 380 nm and 730 nm was shown.

Next, from the spectral reflectance R, the spectral density SD is changed to D = −0.5 × LOG ₁₀ (R).
It is calculated by the formula of Here, the spectral density of color 1 is SD1 (λ), the spectral density of color W1 is SDW1 (λ), the spectral density of color 2 is SD2 (λ), the spectral density of color W2 is SDW2 (λ), and the color Wd is The spectral density is SDWd (λ). Furthermore, the spectral density SDM1 (λ) of the color M1 (magenta (M) printed on the printing paper C), the spectral density SDM2 (λ) of the color M2 (spot color (red) printed on the printing paper C), and the color M12 (printing) Spectral density SDM12 (λ) of a special color (red) printed on magenta (M) on paper C, respectively.
SDM1 (λ) = r1 × (SD1 (λ) −SDW1 (λ)) + SDWd (λ)
SDM2 (λ) = r2 × (SD2 (λ) −SDW2 (λ)) + SDWd (λ)
SDM12 (λ) = a × r1 × (SD1 (λ) −SDW1 (λ)) + b × r2 × (SD2 (λ) −SDW2 (λ)) + SDWd (λ) −c × a × r1 × (SD1 (λ ) −SDW1 (λ)) × b × r2 × (SD2 (λ) −SDW2 (λ))
9 is calculated for each wavelength, and the result is shown in FIG. At this time, each coefficient is
Transparency coefficient a = 0.8, Trapping rate coefficient b = 0.9, Overprint correction coefficient c = 0.75, r1 = 1 (Because printing papers A and C are the same high quality paper, the inter-paper density adjustment coefficient is 1), r2 = 0.75
It was.

  Next, the color system values are obtained from the spectral densities SDM1 (λ), SDM2 (λ), and SDM12 (λ). The process of obtaining the color system value from the spectral density is generally known, so only an outline will be described.

First, X, Y, and Z values of the XYZ color system are obtained. First, the spectral reflectance RM (λ) of each wavelength from the spectral density SDM (λ)
RM (λ) = 10 ^ (− 2 SDM (λ))
(However, the notation a ^ b indicates a to the bth power.)
X is obtained by adding the value obtained by multiplying RM (λ) by x (λ) for all wavelengths (380 nm to 730 nm), and Y is obtained by multiplying RM (λ) by y (λ). The value is obtained by adding the values for all wavelengths (380 nm to 730 nm), and Z is obtained by adding the value obtained by multiplying RM (λ) by z (λ) for all wavelengths (380 nm to 730 nm). These x (λ), y (λ), and z (λ) are defined as CIE1931 XYZ color system color matching functions x (λ) defined by CIE (Commission Internationale de l'Eclairage (International Lighting Commission)), y (λ), z (λ) (in CIE 1931, a bar (-) is attached above x, y, z) and the value of the D50 standard light source. is there. In this way
X, Y, Z of the color Wd (ground color of the printing paper C) are
(X, Y, Z) = (79.6646181, 82.581194, 67.549634),
X, Y, Z of color M1 (magenta (M) printed on printing paper C)
(X, Y, Z) = (29.5311404, 14.95111495, 14.9455192),
X, Y, Z of color M2 (spot color (red) printed on printing paper C) are
(X, Y, Z) = (49.49643233, 32.4768588, 9.427097377),
X, Y, and Z of color M12 (color printed by printing a special color (red) on magenta (M) on printing paper C)
(X, Y, Z) = (28.80409146, 14.223776945, 4.980801815)
It is obtained.

Then, the L * value, a * value, and b * value of the L * a * b * color system value are obtained from the X, Y, and Z values of the XYZ color system. First,
Xd = X / X0, Yd = Y / Y0, and Zd = Z / Z0. However, X0, Y0, and Z0 are values obtained by adding x (λ), y (λ), and z (λ) for all wavelengths (380 nm to 730 nm), respectively. And
X2 = Xd ^ (1/3); Xd> 0.008856 = Xd × 7.787 + 16/116; otherwise Y2 = Yd ^ (1/3); Yd> 0.008856 = Yd × 7.787 + 16/116; otherwise Z2 = Zd ^ (1/3); if Zd> 0.008856 = Zd × 7.787 + 16/116; otherwise, X2, Y2, Z2 are determined.
L * = Y2 × 116-16
a * = 500 × (X2−Y2)
b * = 200 × (Y2-Z2)
And L * value, a * value, b * value of L * a * b * color system values,
The value of the L * a * b * color system of the color Wd (ground color of the printing paper C) is
(L *, a *, b *) = (92.82281082, 0.092181886, 0.510349052),
The value of the L * a * b * color system of color M1 (magenta (M) printed on printing paper C) is
(L *, a *, b *) = (45.568484761, 71.649491975, −7.0005201141),
The value of the L * a * b * color system of color M2 (spot color (red) printed on printing paper C) is
(L *, a *, b *) = (63.69639212, 56.8444656, 40.368258799),
The value of the L * a * b * color system of color M12 (color printed by printing a special color (red) on magenta (M) on printing paper C) is
(L *, a *, b *) = (44.97612066, 71.420421, 27.061558076)
It becomes. Further, FIG. 10 shows the above-obtained values of X, Y, Z, Xd = X / X0, Yd = Y / Y0, Zd = Z / Z0, and L * a * b * color system value L *. The values, a * values, and b * values are listed.

  In this embodiment, the case where a measuring device capable of measuring the spectral density is used is described. However, the spectral density cannot be measured, and the value and density of the L * a * b * color system or the XYZ color system. In the case of a measuring instrument that can measure only the above value, it is possible to obtain a plurality of density values by the method as in Japanese Patent Application No. 2003-292889 and use it instead of the spectral density.

It is a functional block diagram which shows the structure of the color proof production apparatus which concerns on this invention. It is explanatory drawing which shows an example of a structure of the color characteristic table of this Embodiment. It is explanatory drawing which shows an example of a structure of the coefficient table of this Embodiment. It is explanatory drawing which shows an example of a structure of the color table of this Embodiment. It is explanatory drawing which shows an example of a structure of the color channel table of this Embodiment. It is a flowchart which shows the procedure of the color estimation method of this invention. It is a flowchart which shows the process sequence in the color proof production apparatus to which the color estimation method of this invention is applied. Spectral reflectance R1 (λ) of magenta (M), spectral reflectance RW1 (λ) of the ground color of the printing paper A, spectral reflectance R2 (λ) of the special color (red), spectral reflectance of the ground color of the printing paper B 6 is a diagram illustrating measurement results of a rate RW2 (λ) and a ground color spectral reflectance RWd (λ) of the printing paper C. FIG. FIG. 9 is a diagram showing each spectral density obtained from each spectral reflectance shown in FIG. 8, and spectral density SDM1 (λ), SDM2 (λ), and SDM12 (λ) of colors obtained by the color estimation method of the present invention. . It is a figure which shows an example of the color estimation result performed using the color estimation method in this Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Control part 2 Color calculation part 21 Color calculation means 22 Color characteristic table 23 Coefficient table 24 Color table 25 Input means 3 Color channel creation part 31 Color channel calculation means 32 Reference table 33 Color channel table 4 Image recording part

Claims (26)

Based on the color of the color material on the recording medium on which the color material containing the pigment is printed, the color obtained by printing the color material on another recording medium having a surface state different from the recording medium is estimated. A color estimation method,
A first measurement step of measuring a value of a color characteristic of the color material on a recording medium on which the color material is printed;
A second measurement step of measuring a value of a color characteristic of the recording medium on which the color material is printed;
A third measuring step of measuring the value of the color characteristic of another recording medium having a different surface state;
Using the color characteristic values measured in the first to third measurement steps, based on the surface state difference between the recording medium on which the color material is printed and the other recording medium having a different surface state, the surface state An estimation step of estimating a color obtained by printing the color material on another recording medium having a different color. The value of the color characteristic is a spectral density for each wavelength λ of light,
In the first measurement step, a spectral density SD1 (λ) is measured for each wavelength λ of light of the color material on a recording medium on which the color material is printed,
The second measuring step measures a spectral density SDW1 (λ) for each wavelength λ of the light of the recording medium on which the color material is printed,
The third measuring step measures a spectral density SDWd (λ) for each wavelength λ of light of another recording medium having a different surface state,
The estimation step includes a difference between the spectral density SD1 (λ) and the spectral density SDW1 (λ) based on a difference in surface state between the recording medium on which the color material is printed and another recording medium having a different surface state. Is added to the spectral density SDWd (λ), and the result is estimated as the spectral density SDM1 (λ) of the color obtained by printing the color material on another recording medium having a different surface state. The color estimation method according to claim 1. The method further includes a preparatory step of preparing a coefficient based on a difference in surface state between the recording medium on which the color material is printed in advance and another recording medium having a different surface state,
The color estimation method according to claim 2, wherein the adjustment in the estimation step is performed by multiplying a difference between the spectral density SD1 (λ) and the spectral density SDW1 (λ) by the coefficient.   4. The color estimation method according to claim 2, wherein the estimating step estimates the spectral density SDM1 (λ), and further converts the spectral density SDM1 (λ) into a color system value.   The color estimation method according to any one of claims 1 to 4, wherein the color material includes a plurality of color materials each including a pigment printed thereon. The color of the color material on the first recording medium printed with the first color material containing the pigment and the color material on the second recording medium printed with the second color material containing the pigment A color obtained by printing the second color material over the first color material on another recording medium having a surface state different from that of the first or second recording medium based on the color. A color estimation method for estimating
A first measuring step of measuring a value of a color characteristic of the first color material on the first recording medium;
A second measuring step of measuring a value of a color characteristic of the first recording medium;
A third measuring step for measuring a value of a color characteristic of the second color material on the second recording medium;
A fourth measuring step of measuring a value of the color characteristic of the second recording medium;
A fifth measuring step of measuring a value of color characteristics of another recording medium having a different surface state;
Based on the difference in surface condition between the first and second recording media and the other recording medium having a different surface condition, using the color characteristic values measured in the first to fifth measurement steps, the surface An estimation step for estimating a color obtained by printing the second color material on the first color material on another recording medium having a different state. Method. The value of the color characteristic is a spectral density for each wavelength λ of light,
The first measuring step measures a spectral density SD1 (λ) for each wavelength λ of the light of the color of the first color material on the first recording medium,
The second measuring step measures a spectral density SDW1 (λ) for each wavelength λ of the light of the first recording medium,
The third measuring step measures a spectral density SD2 (λ) with respect to each wavelength λ of the light of the color of the second color material on the second recording medium,
In the fourth measuring step, the spectral density SDW2 (λ) is measured for each wavelength λ of the light of the second recording medium,
In the fifth measuring step, a spectral density SDWd (λ) is measured for each wavelength λ of light of another recording medium having a different surface state.
The estimation step uses the spectral density measured in the first to fifth measurement steps, and is based on the difference in surface state between the first and second recording media and the other recording media having different surface states. The spectral density SDM12 (λ) of a color obtained by printing the second color material on the first color material and printing on another recording medium having a different surface state is estimated. The color estimation method described in 1.   In the estimation step, for each wavelength λ of the light, the spectral density SD1 (λ) and the spectral density based on the difference in surface state between the first recording medium and another recording medium having a different surface state. The spectral density SD2 (λ) and the spectral density SDW2 are based on a value obtained by adjusting a difference from SDW1 (λ) and a difference in surface state between the second recording medium and another recording medium having a different surface state. The color estimation method according to claim 7, wherein a value obtained by adjusting a difference from (λ) and the spectral density SDWd (λ) are added, and the result is estimated as the spectral density SDM12 (λ).   In the estimation step, for each wavelength λ of the light, the spectral density SD1 (λ) and the spectral density based on the difference in surface state between the first recording medium and another recording medium having a different surface state. Based on a value proportional to a value obtained by adjusting a difference from SDW1 (λ) and a difference in surface state between the second recording medium and another recording medium having a different surface state, the spectral density SD2 (λ) The value proportional to a value obtained by adjusting a difference from the spectral density SDW2 (λ) and the spectral density SDWd (λ) are added, and the result is estimated as the spectral density SDM12 (λ). Color estimation method.   In the estimation step, for each wavelength λ of the light, the spectral density SD1 (λ) and the spectral density based on the difference in surface state between the first recording medium and another recording medium having a different surface state. Based on a value proportional to a value obtained by adjusting a difference from SDW1 (λ) and a difference in surface state between the second recording medium and another recording medium having a different surface state, the spectral density SD2 (λ) The value proportional to the value obtained by adjusting the difference from the spectral density SDW2 (λ) and the spectral density SDWd (λ) are added, and a value proportional to the product of the two values proportional to the adjusted value is obtained. The color estimation method according to claim 7, wherein the addition result is subtracted and the result is estimated as the spectral density SDM12 (λ). A preparatory step of preparing each coefficient based on a difference in surface condition between each of the first and second recording media and the other recording medium having a different surface condition in advance;
The adjustment in the estimation step is performed by adding the respective coefficients to the difference between the spectral density SD1 (λ) and the spectral density SDW1 (λ) and the difference between the spectral density SD2 (λ) and the spectral density SDW2 (λ). The color estimation method according to claim 8, wherein the color estimation method is performed by multiplying.   12. The color estimation method according to claim 7, wherein the estimating step estimates the spectral density SDM12 (λ), and further converts the spectral density SDM12 (λ) into a color system value. .   The color estimation method according to any one of claims 6 to 12, wherein the first color material includes a plurality of color materials each including a pigment printed thereon. Based on the color of the color material on the recording medium on which the color material containing the pigment is printed, the halftone image of the color material is printed on another recording medium having a surface state different from that of the recording medium. A color adjustment method for performing color adjustment by changing the output intensity of a plurality of basic colors so as to reproduce the color of a halftone dot line portion as a target color,
A storage step for storing in advance a reference table indicating a correspondence relationship between the output intensity of the plurality of basic colors and the value of the L * a * b * color system;
A recording medium on which the color material is printed using values of color characteristics of the color material on the recording medium on which the color material is printed, a recording medium on which the color material is printed, and another recording medium having a different surface state L * a * b * color system of colors obtained by printing the color material on another recording medium having a different surface condition based on the difference in surface condition between the recording medium and the other recording medium having a different surface condition An estimation stage for estimating the value of
A color channel table for obtaining a combination of the output intensities of the plurality of basic colors for reproducing the target color based on the value of the L * a * b * color system obtained in the estimation step and the reference table And a generation stage for generating
A color adjustment method, wherein color adjustment is performed by changing output intensities of the plurality of basic colors based on the color channel table. The value of the color characteristic is a spectral density for each wavelength λ of light,
The estimation step includes spectral densities SD1 (as spectral densities of the color material on the recording medium on which the color material is printed, the recording medium on which the color material is printed, and another recording medium having a different surface state. λ), spectral density SDW1 (λ), and spectral density SDWd (λ), and the spectral analysis based on the difference in surface condition between the recording medium on which the color material is printed and the other recording medium having a different surface condition. The value obtained by adjusting the difference between the density SD1 (λ) and the spectral density SDW1 (λ) is added to the spectral density SDWd (λ), and the result is added to the other recording medium having a different surface state. The color adjustment according to claim 14, wherein the spectral density SDM1 (λ) of the color obtained by printing is estimated, and the spectral density SDM1 (λ) is converted into a value of the L * a * b * color system. Method. The method further includes a preparatory step of preparing a coefficient based on a difference in surface state between the recording medium on which the color material is printed in advance and another recording medium having a different surface state,
The color adjustment method according to claim 15, wherein the adjustment in the estimation step is performed by multiplying a difference between the spectral density SD1 (λ) and the spectral density SDW1 (λ) by the coefficient.   The color adjustment method according to any one of claims 14 to 16, wherein the color material includes a plurality of color materials each including a pigment printed thereon. The color of the color material on the first recording medium printed with the first color material containing the pigment and the color material on the second recording medium printed with the second color material containing the pigment A halftone image line portion obtained by printing a halftone image of the first and second color materials on another recording medium having a surface state different from that of the first and second recording media based on the color. A color adjustment method for performing color adjustment by changing the output intensity of a plurality of basic colors so as to reproduce a color as a target color,
A storage step for storing in advance a reference table indicating a correspondence relationship between the output intensity of the plurality of basic colors and the value of the L * a * b * color system;
The first color material on the first recording medium, the first recording medium, the second color material on the second recording medium, the second recording medium, and the surface state Using the value of the color characteristic of another different recording medium, another recording having a different surface condition is performed based on the difference in surface condition between the first and second recording media and the other recording medium having a different surface condition. An estimation step of estimating a value of an L * a * b * color system of a color obtained by printing the second color material on the first color material on a medium;
A color channel table for obtaining a combination of the output intensities of the plurality of basic colors for reproducing the target color based on the value of the L * a * b * color system obtained in the estimation step and the reference table And a generation stage for generating
A color adjustment method, wherein color adjustment is performed by changing output intensities of the plurality of basic colors based on the color channel table. The value of the color characteristic is a spectral density for each wavelength λ of light,
The estimation step includes the first color material on the first recording medium, the first recording medium, the second color material on the second recording medium, the second recording medium, and , Spectral density SD1 (λ), spectral density SDW1 (λ), spectral density SD2 (λ), spectral density SDW2 (λ), and spectral density SDWd as spectral densities of the other recording media having different surface states. (Λ) is used, and the first and second recording media and the other recording media having different surface states are used to place the first recording medium on the other recording media having different surface states on the first recording medium. A spectral density SDM12 (λ) of a color obtained by printing the second color material on top of a color material is estimated, and the spectral density SDM1 (λ) is further expressed by L * a * b * color specification. The color adjustment method according to claim 18, wherein the color adjustment method is converted to a system value.   In the estimation step, for each wavelength λ of the light, the spectral density SD1 (λ) and the spectral density based on the difference in surface state between the first recording medium and another recording medium having a different surface state. The spectral density SD2 (λ) and the spectral density SDW2 are based on a value obtained by adjusting a difference from SDW1 (λ) and a difference in surface state between the second recording medium and another recording medium having a different surface state. The color adjustment method according to claim 19, wherein a value obtained by adjusting a difference from (λ) and the spectral density SDWd (λ) are added, and the result is estimated as the spectral density SDM12 (λ).   In the estimation step, for each wavelength λ of the light, the spectral density SD1 (λ) and the spectral density based on the difference in surface state between the first recording medium and another recording medium having a different surface state. Based on a value proportional to a value obtained by adjusting a difference from SDW1 (λ) and a difference in surface state between the second recording medium and another recording medium having a different surface state, the spectral density SD2 (λ) The value proportional to the value obtained by adjusting the difference from the spectral density SDW2 (λ) and the spectral density SDWd (λ) are added, and the result is estimated as the spectral density SDM12 (λ). Color adjustment method.   In the estimation step, for each wavelength λ of the light, the spectral density SD1 (λ) and the spectral density based on the difference in surface state between the first recording medium and another recording medium having a different surface state. Based on a value proportional to a value obtained by adjusting a difference from SDW1 (λ) and a difference in surface state between the second recording medium and another recording medium having a different surface state, the spectral density SD2 (λ) The value proportional to the value obtained by adjusting the difference from the spectral density SDW2 (λ) and the spectral density SDWd (λ) are added, and a value proportional to the product of the two values proportional to the adjusted value is obtained. The color adjustment method according to claim 19, wherein the addition result is subtracted and the result is estimated as the spectral density SDM12 (λ). A preparatory step of preparing each coefficient based on a difference in surface condition between each of the first and second recording media and the other recording medium having a different surface condition in advance;
The adjustment in the estimation step is performed by adding the respective coefficients to the difference between the spectral density SD1 (λ) and the spectral density SDW1 (λ) and the difference between the spectral density SD2 (λ) and the spectral density SDW2 (λ). The color adjustment method according to any one of claims 20 to 22, wherein the color adjustment method is performed by multiplying.   The color adjustment method according to any one of claims 18 to 23, wherein the first color material includes a plurality of color materials each including a pigment printed thereon. Based on the color of the color material on the recording medium on which the color material containing the pigment is printed, the halftone image of the color material is printed on another recording medium having a surface state different from that of the recording medium. A color image forming apparatus that forms a color image while reproducing the output intensity of a plurality of basic colors with the color of a halftone dot line portion as a target color,
A reference table indicating a correspondence relationship between output intensity of the plurality of basic colors and values of the L * a * b * color system;
A recording medium on which the color material is printed using values of color characteristics of the color material on the recording medium on which the color material is printed, a recording medium on which the color material is printed, and another recording medium having a different surface state L * a * b * color system of colors obtained by printing the color material on another recording medium having a different surface condition based on the difference in surface condition between the recording medium and the other recording medium having a different surface condition An estimation means for estimating the value of
A color channel table for obtaining a combination of the output intensities of the plurality of basic colors for reproducing the target color based on the value of the L * a * b * color system obtained by the estimating means and the reference table Generating means for generating
A color image forming apparatus, comprising: a control unit configured to control the output intensity of the plurality of basic colors based on the color channel table when forming the color image. The color of the color material on the first recording medium printed with the first color material containing the pigment and the color material on the second recording medium printed with the second color material containing the pigment A halftone image line portion obtained by printing a halftone image of the first and second color materials on another recording medium having a surface state different from that of the first and second recording media based on the color. A color image forming apparatus that forms a color image while changing and reproducing the output intensity of a plurality of basic colors using a color as a target color,
A reference table indicating a correspondence relationship between output intensity of the plurality of basic colors and values of the L * a * b * color system;
The first color material on the first recording medium, the first recording medium, the second color material on the second recording medium, the second recording medium, and the surface state Using the value of the color characteristic of another different recording medium, another recording having a different surface condition is performed based on the difference in surface condition between the first and second recording media and the other recording medium having a different surface condition. Estimating means for estimating an L * a * b * color system value of a color obtained by printing the second color material over the first color material on a medium;
A color channel table for obtaining a combination of the output intensities of the plurality of basic colors for reproducing the target color based on the value of the L * a * b * color system obtained by the estimating means and the reference table Generating means for generating
A color image forming apparatus, comprising: a control unit configured to control the output intensity of the plurality of basic colors based on the color channel table when forming the color image.

Images