COLOR PROCESSING METHOD AND APPARATUS

Abstract

When generating a color conversion table for converting a device independent color into a device color, a conversion target color of the device independent color corresponding to a lattice point of the color conversion table is set based on color reproduction information indicating the relationship between the device color and device independent color. The conversion target color is changed to generate a plurality of neighbor colors of the conversion target color. The conversion target color and the plurality of neighbor colors are converted into device colors based on the color reproduction information, and the device color corresponding to the conversion target color is calculated from the conversion results.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are views showing a monitor gamut and a printer gamut, respectively, as an example of a color gamut;

FIG. 2 is a block diagram showing the structure of a color processing apparatus;

FIG. 3 is a flowchart illustrating an exemplary operation of a printer driver.

FIG. 4A is a view showing the structure of a color conversion LUT;

FIG. 4B is a view showing the data structure of the color conversion LUT;

FIG. 5 is a flowchart illustrating an exemplary operation of a color conversion LUT generation application;

FIG. 6 is a flowchart illustrating details of mapping;

FIG. 7 is a view illustrating generation of neighbor colors;

FIG. 8 is a flowchart illustrating details of gamut mapping;

FIGS. 9A and 9B are views illustrating gamut mapping.

FIG. 10 is a view showing an example of a nonlinear mapping function;

FIG. 11 is a view illustrating a mapping result;

FIG. 12 is a flowchart illustrating details of RGB value calculation;

FIG. 13 is a view illustrating generation of neighbor colors; and

FIG. 14 is a flowchart illustrating details of Lab value to RGB value conversion.

Claims

1. A color processing method comprising: obtaining gamut information of a color gamut of a destination;setting a mapping target color corresponding to a lattice point of a color conversion table;generating a plurality of neighbor colors of the mapping target color by changing a color value of the mapping target color;mapping the mapping target color and the plurality of neighbor colors in the color gamut of the destination based on gamut information;calculating a mapped color corresponding to the mapping target color from results of the mapping of the mapping target color and the plurality of neighbor colors; andstoring a calculation result in the color conversion table.

2. The method according to claim 1, wherein the plurality of neighbor colors are generated by changing at least one of a lightness value, a chroma value, and a hue value of the mapping target color.

3. The method according to claim 1, further comprising: determining whether the mapped color falls inside the color gamut of the destination; andclipping the mapped color onto a boundary of the color gamut of the destination when the mapped color falls outside the color gamut of the destination.

4. The method according to claim 1, wherein the mapping is performed by using a convergence point set in the color gamut of the destination.

5. A color processing apparatus comprising: an obtaining section, arranged to obtain gamut information of a color gamut of a destination;a setting section, arranged to set a mapping target color corresponding to a lattice point of a color conversion table;a generator, arranged to generate a plurality of neighbor colors of the mapping target color by changing a color value of the mapping target color;a mapping section, arranged to map the mapping target color and the plurality of neighbor colors in the color gamut of the destination based on gamut information;a calculator, arranged to calculate a mapped color corresponding to the mapping target color from results of the mapping of the mapping target color and the plurality of neighbor colors; anda storing section, arranged to store a calculation result in the color conversion table.

6. A computer program product stored on a computer-readable medium comprising computer program code for a color processing, the computer program product comprising: computer-executable instruction for obtaining gamut information of a color gamut of a destination;computer-executable instruction for setting a mapping target color corresponding to a lattice point of a color conversion table;computer-executable instruction for generating a plurality of neighbor colors of the mapping target color by changing a color value of the mapping target color;computer-executable instruction for mapping the mapping target color and the plurality of neighbor colors in the color gamut of the destination based on the gamut information;computer-executable instruction for calculating a mapped color corresponding to the mapping target color from results of the mapping of the mapping target color and the plurality of neighbor colors; andcomputer-executable instruction for storing a calculation result in the color conversion table.