Method and system for predicting print colors
Inherent reflectances and scattering coefficients of color materials to be used in producing a print are calculated, and target printing base solid predicted reflectances are calculated using the calculated inherent reflectances and scattering coefficients, and the spectral reflectance of a target printing base, according to the Kubelka-Munk theory. Colorimetric values are calculated from the target printing base solid predicted reflectances. Differences are determined between calculated target printing base solid predicted colorimetric values and standard printing base solid calorimetric values obtained from a color chart, whereupon target printing base halftone differential predicted calorimetric values are calculated from the determined differences. The target printing base halftone differential predicted colorimetric values and standard printing base halftone colorimetric values of the color chart are added, and a print predicting profile is generated.
1. A method of predicting colors of a print produced by a printing press, comprising the step of:
with a calculating device predicted colorimetric values of a solid print to be produced on a target printing base with color materials, based on a spectral reflectance of said target printing base and property values of said color materials, said solid print having a combination of area ratios of 0% and 100%;
determining differences between measured colorimetric values of a solid color chart produced on a standard printing base with said color materials and having a combination of area ratios of 0% and 100%, and said predicted colorimetric values; and
predicting colors of a print to be produced on said target printing base with said color materials and having an arbitrary area ratio, based on said differences.
2. A method according to claim 1 , wherein said property values comprise two independent property values from among inherent reflectances, scattering coefficients, and absorption coefficients of said color materials.
3. A method according to claim 1 , further comprising the step of:
adding adjusted differences produced by adjusting said differences depending on said arbitrary area ratio, to the measured colorimetric values of said color chart produced on said standard printing base with said color materials and having a predetermined area ratio, thereby to calculate predicted calorimetric values of the print to be produced on said target printing base with said color materials and having said arbitrary area ratio.
4. A method according to claim 1 , wherein the colors of the print to be produced on said target printing base with said color materials are predicted based on a Kubelka-Munk equation.
5. A method according to claim 3 , wherein said adjusted differences depending on said arbitrary area ratio are adjusted based on a Neugebauer equation.
6. A method according to claim 1 , further comprising the steps of:
setting a standard printing base profile representing the relationship between measured calorimetric values of said color chart produced on said standard printing base with said color materials and having a predetermined area ratio, and said area ratio; and
correcting said standard printing base profile according to said differences so as to generate a target printing base profile for said target printing base.
7. A system for predicting colors of a print produced by a printing press, comprising:
a solid predicted colorimetric value calculating device for calculating predicted colorimetric values of a solid print to be produced on a target printing base with color materials and having a combination of area ratios of 0% and 100%, based on a spectral reflectance of said target printing base and property values of said color materials;
a solid difference calculating device for calculating solid differences between measured colorimetric values of a solid color chart, produced on a standard printing base with said color materials and having a combination of area ratios of 0% and 100%, and said predicted colorimetric values;
a halftone differential calculating device for calculating halftone differences of a print produced on said target printing base with said color materials and having a halftone area ratio, based on said solid differences; and
a print predicting profile generating device for generating a print predicting profile for predicting colors of a print to be produced on said target printing base with said color materials, using the measured colorimetric values of said color chart produced on said standard printing base with said color materials and having a predetermined area ratio, and said halftone differences,
whereby the colors of the print can be predicted using said print predicting profile.
8. A system according to claim 7 , wherein said property values comprise two independent property values from among inherent reflectances, scattering coefficients, and absorption coefficients of said color materials.
9. A system for predicting colors of a print produced by a printing press, comprising:
a solid predicted colorimetric value calculating device for calculating predicted colorimetric values of a solid print to be produced on a target printing base with color materials and having a combination of area ratios of 0% and 100%, based on a spectral reflectance of said target printing base and property values of said color materials;
a solid difference calculating device for calculating solid differences between measured calorimetric values of a solid color chart, produced on a standard printing base with said color materials and having a combination of area ratios of 0% and 100%, and said predicted calorimetric values;
a halftone differential calculating device for calculating halftone differences of a print produced on said target printing base with said color materials and having a halftone area ratio, based on said solid differences;
a standard printing base profile generating device for generating a standard printing base profile representing the relationship of the measured colorimetric values with respect to said color chart produced on said standard printing base with said color materials and having a predetermined area ratio; and
a print predicting profile generating device for correcting said standard printing base profile with said halftone differences, so as to generate a print predicting profile for predicting colors of a print to be produced on said target printing base with said color materials,
whereby the colors of the print can be predicted using said print predicting profile.
10. A system according to claim 9 , wherein said property values comprise two independent property values from among inherent reflectances, scattering coefficients, and absorption coefficients of said color materials.