Granted Patent B2

US 7,630,106 · App. 10/836,072 · Granted Dec 8, 2009

Abstract

Claims (39)

1. A system for calibrating a digital color imaging device to a printing press comprising a color profile having a plurality of colorants, colorant values, and associated colorimetric values, the system comprising:

an image source comprising a test pattern adapted for printing a plurality of colors by the digital color imaging device, the test pattern comprising a plurality of patches with scales of greater than 0% and at least one of 100% of a single-colorant value for each colorant and at least one patch with a combination of multiple-colorant values other than black;

an instrument adapted to colorimetrically measure the patches in the printed test pattern; and

a processor adapted to generate a per-channel colorant limit by:

(a) receiving the colorimetric measurements for each patch from the instrument;

(b) determining a minimum colorant limit for each colorant for the digital color imaging device based on a comparison between the measured colorimetric values of the single-colorant printed patches and the colorimetric values of the press profile;

(c) determining a maximum colorant limit for each colorant for the digital color imaging device by:

identifying a colorant value of a minimum black patch with a minimum L-value, wherein a difference between an L-value of the minimum black patch and the L-value of a 100% black colorant patch small; and

identifying a colorant value of a printed patch having one of the following; a maximum chroma and a colorant where oversaturation begins if the colorant is for a colorant other than black; and

(d) determining an optimal colorant limit for each colorant by:

determining a weighted average of the minimum and maximum colorant limits for the black colorant patches; and

determining a colorant value that provides a gray-balance in the at least one patch with a combination of multiple-colorant values that comprise colorants other than black.

2. The system of claim 1 , wherein the test pattern comprises patches having cyan, magenta, yellow and black colorants.

3. The system of claim 1 , wherein the digital color imaging device is adapted to use multi-hue colorants.

4. The system of claim 1 , wherein the instrument comprises a colorimeter.

5. The system of claim 1 , wherein the instrument comprises a spectrophotometer.

6. The system of claim 1 , wherein the instrument comprises a spectrocolorimeter.

7. The system of claim 1 , wherein the colorimetric measurements comprise CIELAB data values.

8. The system of claim 1 , wherein the colorimetric measurements comprise CIEXYZ data values.

9. A method for calibrating a digital color imaging device to a printing press comprising a color profile having a plurality of colorants, colorant values, and associated colorimetric values, the method comprising:

printing a test pattern comprising a plurality of colors on the digital color imaging device, the test pattern comprising a plurality of patches, with scales of great than 0% and at least one of 100% of a single-colorant value for each colorant and at least one patch with a combination of multiple-colorant values other than black;

colorimetrically measuring the patches in the printed test pattern; and

generating a per-channel colorant limit by:

determining a minimum colorant limit for each colorant for the digital color imaging device based on a comparison between the measured colorimetric values of the single-colorant printed patches and the colorimetric values of the press profile;

determining a maximum colorant limit for each colorant for the digital color imaging device by:

identifying in a colorant value of a minimum black patch with a minimum L-value, wherein a difference between an L-value of the minimum black patch and a L-value of the 100% black colorant patch is small; and

identifying a colorant value of a printed patch having on of the following: a maximum chroma and a colorant where oversaturation begins if the colorant is for a colorant other than black; and

determining an optimal colorant limit for each colorant by:

determining a weighted average of the minimum and maximum colorant limits for the black colorant patches; and

determining a colorant value that provides a gray-balance in the at least one patch with a combination of multiple-colorant values that comprise colorants other than black.

10. The method of claim 9 , wherein the test pattern comprises patches having cyan, magenta, yellow and black colorants.

11. The method of claim 9 , wherein the digital color imaging device is adapted to use multi-hue colorants.

12. The method of claim 9 , wherein a colorimetrically measuring comprises measuring the printed test pattern using a colorimeter.

13. The method of claim 9 , wherein colorimetrically measuring comprises measuring the printed test pattern using a spectrophotometer.

14. The method of claim 9 , wherein colorimetrically measuring comprises measuring the printed test pattern using a spectrocolorimeter.

15. The method of claim 9 , wherein the colorimetric measurements comprise CIELAB data values.

16. The method of claim 9 , wherein the colorimetric measurements comprise CIEXYZ data values.

17. The system of claim 1 , further comprising a processor adapted to generate a total colorant limit by receiving the colorimetric values of the printed patches, identifying a patch with a minimum lightness, determining a total area coverage for each patch with the minimum lightness, and setting the total colorant limit to the maximum total area coverage.

18. The system of claim 3 , further comprising a processor adapted to generate a distribution function of multi-hue colorants.

Assignments (11)