Granted Patent B2

US 7,259,893 · App. 10/324,771 · Granted Aug 21, 2007

Abstract

Claims (52)

1. A method for processing input CMYK color data, the method comprising:

converting the input color data to first color data;

processing the first color data to provide second color data;

converting the second color data to third color data using an output profile that comprises an implied gray component replacement level;

estimating a gray component replacement level of the input color data;

estimating the gray component replacement level implied by the output profile;

combining the estimated gray component replacement levels;

determining a black value based on the combined gray component replacement level; and

using the determined black value and the second color data to determine output color data that has a gray component replacement level that substantially matches the gray component replacement level of the input color data.

2. The method of claim 1 , wherein the first color data are device-independent color data.

3. The method of claim 1 , wherein processing comprises processing the first color data in a device-independent color space.

4. The method of claim 1 , wherein the third color data are device-dependent color data.

5. The method of claim 1 , wherein the output profile comprises a lookup table.

6. The method of claim 1 , wherein the input color data comprises CMYK data that approximates a spot color.

7. The method of claim 1 , wherein processing comprises tinting the first color data.

8. A method for processing input CMYK color data, the method comprising:

converting the input color data to a device-independent color space;

processing the converted data in the device-independent color space;

converting the processed data to a device-dependent color space using an output profile;

estimating a gray component replacement level of the input color data;

estimating a gray component replacement level implied by the output profile;

combining the gray component replacement levels;

determining a black value based on the combined gray component replacement level; and

using the determined black value and the processed data to determine output color data that has a gray component replacement level that substantially matches the gray component replacement level of the input color data.

9. The method of claim 8 , wherein the device-independent color space is a CIELAB color space.

10. The method of claim 8 , wherein processing comprises tinting.

11. The method of claim 8 , wherein estimating the gray component replacement level of the input color data comprises determining a lightness level of a black-only component of the input color data.

12. The method of claim 8 , wherein estimating the gray component replacement level implied by the output profile comprises determining a lightness level of a black-only component of the converted processed data.

13. A method for processing input CMYK color data, the method comprising:

converting the input color data to first color data;

tinting the converted data to provide second color data;

converting the second color data to third color data using an output profile;

determining a first lightness component that corresponds to a black-only component of the input color data;

determining a second lightness component that corresponds to a black-only component of the third color data;

blending the first and second lightness components to provide a blended lightness level;

determining a black output component based on the blended lightness level; and

using the black output component and the second color data to determine output color data that has a gray component replacement level that substantially matches a gray component replacement level of the input color data.

14. The method of claim 13 , wherein the output profile comprises a forward lookup table that associates CMYK data with L*a*b* data.

15. The method of claim 14 , wherein determining the first lightness component comprises determining an L* component from the forward table that is associated with the black-only component of the input color data.

16. The method of claim 14 , wherein determining the second lightness component comprises determining an L* component from the forward table that is associated with the black-only component of the third color data.

17. The method of claim 14 , wherein determining output color data comprises fixing the black output component and determining output CMY components from the forward table.

18. The method of claim 13 , wherein the output profile comprises a reverse lookup table that associates L*a*b* data with CMYK data.

19. The method of claim 18 , wherein determining the black output component comprises determining a black component from the reverse table that is associated with the blended lightness level.

20. Apparatus for processing input CMYK color data, the apparatus comprising:

means for converting the input color data to first color data;

means for processing the first color data to provide second color data;

means for converting the second color data to third color data using an output profile;

means for estimating a gray component replacement level of the input CMYK color data;

means for estimating a gray component replacement level implied by the output profile;

means for combining the gray component replacement levels;

means for determining a black value based on the combined gray component replacement level; and

means for using the determined black value and the second color data to provide output color data that has a gray component replacement level that substantially matches the gray component replacement level of the input CMYK color data.

Assignments (12)