COLOR PROCESSING METHOD AND APPARATUS

• US 20070030498A1
• Filed: 07/24/2006
• Published: 02/08/2007
• Est. Priority Date: 08/02/2005
• Status: Active Grant

• Current Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Original Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Inventors: Yamazoe, Manabu, Hori, Ayumi
• Granted Patent: US 8,218,206 B2
• Time in Patent Office: Days
• US Class Current: 358/1.900
• CPC Class Codes: H04N 1/6058 Reduction of colour to a range of reproducible colours, e.g. to ink- reproducible colour gamut

Abstract

The gamut of a printer has poor saturation reproducibility in a low-lightness region, often has a shape from which the gamut is cut away, and sometimes locally forms a part having extremely low color reproducibility. Hence, upon converting colors on a first gamut onto those on a second gamut, a third gamut is generated by transforming the second gamut for the purpose of the conversion, and the colors on the first gamut are mapped onto the third gamut. The colors on the first gamut are converted into those on the second gamut based on the mapping result.

Claims

1. A color processing method of converting colors on a first gamut to colors on a second gamut, comprising the steps of:

generating a third gamut by transforming the second gamut for purpose of the conversion;

mapping the colors on the first gamut onto the third gamut; and

converting the colors on the first gamut into the colors on the second gamut based on the mapping result.

7. The method according to claim 1, wherein the generation step includes a step of generating the third gamut by changing lightness or perceptual chromaticity of a predetermined gamut plane of the second gamut.

8. The method according to claim 7, wherein the predetermined gamut plane is a predetermined hue section or a predetermined lightness section.

9. The method according to claim 1, wherein the generation step comprises the steps of:

setting a plurality of control points on a part of a boundary of a predetermined gamut plane of the second gamut; and

generating the third gamut by transforming the part of the boundary onto a line or curve which connects arbitrary two points of the control points.

10. The method according to claim 9, wherein the two points are any of a black point and white point of the second gamut, basic color points and color points having identical hues as basic colors, intersections between the boundary and chromaticity axes, and a color point designated by a user.

11. The method according to claim 1, wherein the first gamut is a device-independent color space, and the second gamut is a gamut of an image output device.

2. A color processing method of converting colors on a first gamut to colors on a second gamut, comprising the steps of:

performing calorimetric matching reproduction for a partial region in the first gamut;

mapping colors without colors to be reproduced as the colorimetric matching onto a third gamut to which the second gamut is transformed for the conversion; and

transforming the first gamut to the second gamut based on the mapping result in the mapping step.

3. The method according to claim 2, wherein the partial region overlaps the second gamut.

4. The method according to claim 2, wherein the partial region overlaps a predetermined region near a center of the second gamut.

12. The method according to claim 2, wherein the mapping step performs perceptual mapping outside the partial region.

5. A color processing method of converting colors on a first gamut to colors on a second gamut, comprising the steps of:

generating a third gamut by transforming the second gamut for purpose of the conversion;

transforming a partial region of the first gamut as well as the generating step;

mapping the colors on the first gamut onto the third gamut; and

converting the colors on the first gamut into the colors on the second gamut based on the mapping result in the mapping step.

6. A color processing method of converting colors on a first gamut to colors on a second gamut, comprising the steps of:

determining whether or not a color on the first gamut is included in a colorimetrical matching region;

generating a third gamut by transforming the second gamut for purpose of the conversion based on the determination result in the determining step;

mapping the colors on the first gamut onto the third gamut; and

converting the colors on the first gamut into the colors on the second gamut based on the mapping result in the mapping step.

13. A color processing apparatus for converting colors on a first gamut to colors on a second gamut, comprising:

a generator, arranged to generate a third gamut by transforming the second gamut for purpose of the conversion;

a mapping section, arranged to map the colors on the first gamut onto the third gamut; and

a converter, arranged to convert the colors on the first gamut into the colors on the second gamut based on the mapping result.

14. A color processing apparatus for converting colors on a first gamut to colors on a second gamut, comprising:

a performer, arranged to perform calorimetric matching reproduction for a partial region in the first gamut;

a mapping section, arranged to map colors without colors to be reproduced as the calorimetric matching onto a third gamut to which the second gamut is transformed for the conversion; and

a transformer, arranged to transform the first gamut to the second gamut based on the mapping result in the mapping step.

15. A color processing apparatus for converting colors on a first gamut to colors on a second gamut, comprising:

a generator, arranged to generate a third gamut by transforming the second gamut for purpose of the conversion;

a transformer, arranged to transform a partial region of the first gamut as well as the generating step;

a mapping section, arranged to map the colors on the first gamut onto the third gamut; and

a converter, arranged to convert the colors on the first gamut into the colors on the second gamut based on the mapping result in the mapping step.

16. A color processing apparatus for converting colors on a first gamut to colors on a second gamut, comprising:

a determiner, arranged to determine whether or not a color on the first gamut is included in a colorimetry matching region;

a generator, arranged to generate a third gamut by transforming the second gamut for purpose of the conversion based on the determination result in the determining step;

a mapping section, arranged to map the colors on the first gamut onto the third gamut; and

a converter, arranged to convert the colors on the first gamut into the color on the second gamut based on the mapping result in the mapping step.

17. A computer program for a color processing method of converting colors on a first gamut to colors on a second gamut, the method comprising the steps of:

generating a third gamut by transforming the second gamut for purpose of the conversion;

mapping the colors on the first gamut onto the third gamut; and

converting the colors on the first gamut into the colors on the second gamut based on the mapping result.

18. A computer program product stored on a computer readable medium comprising program code for a color processing method of converting colors on a first gamut to colors on a second gamut, the method comprising the steps of:

generating a third gamut by transforming the second gamut for purpose of the conversion;

mapping the colors on the first gamut onto the third gamut; and

converting the colors on the first gamut into the colors on the second gamut based on the mapping result.

19. A computer program for a color processing method of converting colors on a first gamut to colors on a second gamut, the method comprising the steps of:

performing calorimetric matching reproduction for a partial region in the first gamut;

mapping colors without colors to be reproduced as the calorimetric matching onto a third gamut to which the second gamut is transformed for the conversion; and

transforming the first gamut to the second gamut based on the mapping result in the mapping step.

20. A computer program product stored on a computer readable medium comprising program code for a color processing method of converting colors on a first gamut to colors on a second gamut, the method comprising the steps of:

performing calorimetric matching reproduction for a partial region in the first gamut;

mapping colors without colors to be reproduced as the calorimetric matching onto a third gamut to which the second gamut is transformed for the conversion; and

transforming the first gamut to the second gamut based on the mapping result in the mapping step.

21. A computer program for a color processing method of converting colors on a first gamut to colors on a second gamut, the method comprising the steps of:

generating a third gamut by transforming the second gamut for purpose of the conversion;

transforming a partial region of the first gamut as well as the generating step;

mapping the colors on the first gamut onto the third gamut; and

converting the colors on the first gamut into the colors on the second gamut based on the mapping result in the mapping step.

22. A computer program product stored on a computer readable medium comprising program code for a color processing method of converting colors on a first gamut to colors on a second gamut, the method comprising the steps of:

generating a third gamut by transforming the second gamut for purpose of the conversion;

transforming a partial region of the first gamut as well as the generating step;

mapping the colors on the first gamut onto the third gamut; and

converting the colors on the first gamut into the colors on the second gamut based on the mapping result in the mapping step.

23. A computer program for a color processing method of converting colors on a first gamut to colors on a second gamut, the method comprising the steps of:

determining whether or not a color on the first gamut is included in a colorimetrical matching region;

generating a third gamut by transforming the second gamut for purpose of the conversion based on the determination result in the determining step;

mapping the colors on the first gamut onto the third gamut; and

converting the colors on the first gamut into the colors on the second gamut based on the mapping result in the mapping step.

24. A computer program product stored on a computer readable medium comprising program code for a color processing method of converting colors on a first gamut to colors on a second gamut, the method comprising the steps of:

determining whether or not a color on the first gamut is included in a colorimetrical matching region;

generating a third gamut by transforming the second gamut for purpose of the conversion based on the determination result in the determining step;

mapping the colors on the first gamut onto the third gamut; and

converting the colors on the first gamut into the colors on the second gamut based on the mapping result in the mapping step.