Gamut mapping between multiple boundary regions

• US 20050047654A1
• Filed: 08/28/2003
• Published: 03/03/2005
• Est. Priority Date: 08/28/2003
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.), Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Haikin, John S., Newman, Todd D., Henley, Sharon A.
• Granted Patent: US 7,433,077 B2
• Time in Patent Office: Days
• US Class Current: 382/167
• CPC Class Codes: H04N 1/6058 Reduction of colour to a range of reproducible colours, e.g. to ink- reproducible colour gamut

Abstract

Mapping color image data from a source color gamut to a destination color gamut, wherein the mapping includes identifying source color boundary regions in the source color gamut based on descriptor data provided in a source color descriptor data structure, and determining a position of each identified source color boundary region, identifying destination color boundary regions in the destination color gamut based on descriptor data provided in a destination color descriptor data structure, and determining a position of each identified destination color boundary region, and mapping the color image data from the identified source color boundary regions to the identified destination color boundary regions based on a correspondence between the determined positions of the identified source color boundary regions and the determined positions of the identified destination color boundary regions.

Claims

1. A method for mapping color image data from a source color gamut to a destination color gamut, the method comprising the steps of:

identifying source color boundary regions in the source color gamut based on descriptor data provided in a source color descriptor data structure, and determining a position of each identified source color boundary region;

identifying destination color boundary regions in the destination color gamut based on descriptor data provided in a destination color descriptor data structure, and determining a position of each identified destination color boundary region; and

mapping the color image data from the identified source color boundary regions to the identified destination color boundary regions based on a correspondence between the determined positions of the identified source color boundary regions and the determined positions of the identified destination color boundary regions.

2. A method according to claim 1, wherein the identified source color boundary regions include

a source reference color boundary region representing reference colors based on measured colors and including a source reference-white color and a source reference-black color,

a source plausible color boundary region representing plausible colors which are observable, encompassing at least the source reference color boundary region and including a source whitest-white color and a source blackest-black color, and

a source possible color boundary region representing possible colors supported by a predetermined color encoding scheme and encompassing at least the source plausible color boundary region.

3. A method according to claim 2, wherein the identified destination color boundary regions include

a destination reference color boundary region representing reference colors based on measured colors and including a destination reference-white color and a destination reference-black color,

a destination plausible color boundary region representing plausible colors which are observable, encompassing at least the destination reference color boundary region and including a destination whitest-white color and a destination blackest-black color, and

a destination possible color boundary region representing possible colors supported by a predetermined color encoding scheme and encompassing at least the destination plausible color boundary region.

4. A method according to claim 3, wherein, in the case that the source possible color boundary region is larger than the source plausible color boundary region which is larger than the source reference color boundary region, and the destination possible color boundary region is larger than the destination plausible color boundary region which is larger than the destination reference color boundary region, the mapping step

maps all colors disposed between the source possible color boundary region and the source plausible color boundary region to an outer boundary of the destination plausible color boundary region,

maps all colors disposed between the source plausible color boundary region and the source reference color boundary region to be disposed between the destination plausible color boundary region and the destination reference color boundary region, and

maps all colors within the source reference color boundary region to be disposed within the destination reference color boundary region.

5. A method according to claim 4, further comprising the steps of:

identifying a source neutral tone curve based on descriptor data provided in the source color descriptor data structure, the source neutral tone curve including the source whitest-white color, the source reference-white color, a source middle gray color, the source reference-black color and the source blackest-black color; and

identifying a destination neutral tone curve based on descriptor data provided in the destination color descriptor data structure, the destination neutral tone curve including the destination whitest-white color, the destination reference-white color, a destination middle gray color, the destination reference-black color and the destination blackest-black color,

wherein, in the mapping step, the source whitest-white color, the source reference-white color, the source middle gray color, the source reference-black color and the source blackest-black color of the identified source neutral tone curve are mapped to the destination whitest-white color, the destination reference-white color, the destination middle gray color, the destination reference-black color and the destination blackest-black color of the identified destination neutral tone curve, respectively.

6. A method according to claim 3, wherein, in the case that the source possible color boundary region is larger than the source plausible color boundary region which is larger than the source reference color boundary region, and the destination possible color boundary region is equal to the destination plausible color boundary region which is equal to the destination reference color boundary region, the mapping step

maps all colors disposed between the source possible color boundary region and the source plausible color boundary region to an outer boundary of the destination reference color boundary region,

maps all colors disposed between the source plausible color boundary region and the source reference color boundary region to be disposed within the destination reference color boundary region, and

maps all colors within the source reference color boundary region to be disposed within the destination reference color boundary region.

7. A method according to claim 6, further comprising the steps of:

identifying a source neutral tone curve based on descriptor data provided in the source color descriptor data structure, the source neutral tone curve including the source whitest-white color, the source reference-white color, a source middle gray color, the source reference-black color and the source blackest-black color; and

generating a destination neutral tone curve including the destination whitest-white color, the destination reference-white color, a destination middle gray color, the destination reference-black color and the destination blackest-black color,

wherein, in the mapping step, the source whitest-white color, the source reference-white color, the source middle gray color, the source reference-black color and the source blackest-black color of the identified source neutral tone curve are mapped to the destination whitest-white color, the destination reference-white color, the destination middle gray color, the destination reference-black color and the destination blackest-black color of the generated destination neutral tone curve, respectively.

8. A method according to claim 7, wherein all colors disposed between the source plausible color boundary region and the source reference color boundary region are mapped to be disposed within the destination reference color boundary region located in an area between the destination whitest-white color and the destination reference-white color, and in an area between the destination reference-black color and the destination blackest-black color.

9. A method according to claim 7, wherein the destination neutral tone curve is generated based on an analysis of the color image data.

10. A method according to claim 9, wherein the analysis of the color image data determines an amount of the color image data disposed between an image whitest-white color and an image reference-white color, and an amount of the color image data disposed between an image reference-black color and an image blackest-black color.

11. A method according to claim 7, wherein the destination neutral tone curve is generated based on a predetermined scale.

12. A method according to claim 3, wherein, in the case that the destination possible color boundary region is larger than the destination plausible color boundary region which is larger than the destination reference color boundary region, and the source possible color boundary region is equal to the source plausible color boundary region which is equal to the source reference color boundary region, the mapping step

maps all colors disposed at an outer boundary of the source reference color boundary region to an outer boundary of the destination plausible color boundary region,

maps a first set of colors disposed within the source reference color boundary region to be disposed between the destination plausible color boundary region and the destination reference color boundary region, and

maps a second set of colors disposed within the source reference color boundary region to be disposed within the destination reference color boundary region.

13. A method according to claim 12, further comprising the steps of:

identifying a destination neutral tone curve based on descriptor data provided in the destination color descriptor data structure, the destination neutral tone curve including the destination whitest-white color, the destination reference-white color, a destination middle gray color, the destination reference-black color and the destination blackest-black color; and

generating a source neutral tone curve including the source whitest-white color, the source reference-white color, a source middle gray color, the source reference-black color and the source blackest-black color,

wherein, in the mapping step, the source whitest-white color, the source reference-white color, the source middle gray color, the source reference-black color and the source blackest-black color of the generated source neutral tone curve are mapped to the destination whitest-white color, the destination reference-white color, the destination middle gray color, the destination reference-black color and the destination blackest-black color of the identified destination neutral tone curve, respectively.

14. A method according to claim 13, wherein the first set of colors disposed within the source reference color boundary region are located in an area between the source whitest-white color and the source reference-white color, and in an area between the source reference-black color and the source blackest-black color.

15. A method according to claim 13, wherein the source neutral tone curve is generated based on an analysis of the color image data.

16. A method according to claim 15, wherein the analysis of the color image data determines an amount of the color image data disposed between an image whitest-white color and an image reference-white color, and an amount of the color image data disposed between an image reference-black color and an image blackest-black color.

17. A method according to claim 13, wherein the source neutral tone curve is generated based on a predetermined scale.

18. A method according to claim 3, wherein, in the case that the source possible color boundary region is equal to the source plausible color boundary region which is equal to the source reference color boundary region, and the destination possible color boundary region is equal to the destination plausible color boundary region which is equal to the destination reference color boundary region, the mapping step

maps all colors disposed within the source reference color boundary region to be disposed within the destination reference color boundary region.

19. A method according to claim 18, further comprising the steps of:

generating a destination neutral tone curve including the destination whitest-white color, the destination reference-white color, a destination middle gray color, the destination reference-black color and the destination blackest-black color; and

generating a source neutral tone curve including the source whitest-white color, the source reference-white color, a source middle gray color, the source reference-black color and the source blackest-black color,

wherein, in the mapping step, the source whitest-white color, the source reference-white color, the source middle gray color, the source reference-black color and the source blackest-black color of the generated source neutral tone curve are mapped to the destination whitest-white color, the destination reference-white color, the destination middle gray color, the destination reference-black color and the destination blackest-black color of the generated destination neutral tone curve, respectively.

20. A method according to claim 19, wherein the mapping of the colors disposed within the source reference color boundary region to be disposed within the destination reference color boundary region includes

mapping all colors disposed in an area between the source whitest-white color and the source reference-white color to be disposed in an area between the destination whitest-white color and the destination reference-white color, and

mapping all colors disposed in an area between the source reference-black color and the source blackest-black color to be disposed in an area between the destination reference-black color and the destination blackest-black color.

21. A method according to claim 19, wherein the source neutral tone curve and the destination neutral tone curve are each generated based on an analysis of the color image data.

22. A method according to claim 21, wherein the analysis of the color image data determines an amount of the color image data disposed between an image whitest-white color and an image reference-white color, and an amount of the color image data disposed between an image reference-black color and an image blackest-black color.

23. A method according to claim 19, wherein the source neutral tone curve is generated based on a predetermined scale.

25. A computing device for mapping color image data from a source color gamut to a destination color gamut, comprising:

a program memory for storing process steps executable to perform a method according to any of claims 1 to 24; and

a processor for executing the process steps stored in said program memory.

26. Computer-executable process steps stored on a computer readable medium, said computer-executable process steps for mapping color image data from a source color gamut to a destination color gamut, said computer-executable process steps comprising process steps executable to perform a method according to any of claims 1 to 24.

27. A computer-readable medium which stores computer-executable process steps, the computer-executable process steps for mapping color image data from a source color gamut to a destination color gamut, said computer-executable process steps comprising process steps executable to perform a method according to any of claims 1 to 24.

24. A method for mapping color image data from a source color gamut to a destination color gamut, the method comprising the steps of:

identifying source color boundary regions in the source color gamut based on descriptor data provided in a source color descriptor data structure, and determining a position of each identified source color boundary region, the source color boundary regions including a source reference color boundary region representing reference colors based on measured colors and including a source reference-white color and a source reference-black color, a source plausible color boundary region representing plausible colors which are observable, encompassing at least the source reference color boundary region and including a source whitest-white color and a source blackest-black color, and a source possible color boundary region representing possible colors supported by a predetermined color encoding scheme and encompassing at least the source plausible color boundary region;

identifying destination color boundary regions in the destination color gamut based on descriptor data provided in a destination color descriptor data structure, and determining a position of each identified destination color boundary region, the destination color boundary regions including a destination reference color boundary region representing reference colors based on measured colors and including a destination reference-white color and a destination reference-black color, a destination plausible color boundary region representing plausible colors which are observable, encompassing at least the destination reference color boundary region and including a destination whitest-white color and a destination blackest-black color, and a destination possible color boundary region representing possible colors supported by a predetermined color encoding scheme and encompassing at least the destination plausible color boundary region;

mapping, in the case that the source possible color boundary region is larger than the source plausible color boundary region which is larger than the source reference color boundary region, and the destination possible color boundary region is larger than the destination plausible color boundary region which is larger than the destination reference color boundary region,

all colors disposed between the source possible color boundary region and the source plausible color boundary region to an outer boundary of the destination plausible color boundary region,

all colors disposed between the source plausible color boundary region and the source reference color boundary region to be disposed between the destination plausible color boundary region and the destination reference color boundary region, and

all colors within the source reference color boundary region to be disposed within the destination reference color boundary region;

mapping, in the case that the source possible color boundary region is larger than the source plausible color boundary region which is larger than the source reference color boundary region, and the destination possible color boundary region is equal to the destination plausible color boundary region which is equal to the destination reference color boundary region,

all colors disposed between the source possible color boundary region and the source plausible color boundary region to an outer boundary of the destination reference color boundary region,

all colors disposed between the source plausible color boundary region and the source reference color boundary region to be disposed within the destination reference color boundary region, and

all colors within the source reference color boundary region to be disposed within the destination reference color boundary region;

mapping, in the case that the destination possible color boundary region is larger than the destination plausible color boundary region which is larger than the destination reference color boundary region, and the source possible color boundary region is equal to the source plausible color boundary region which is equal to the source reference color boundary region,

all colors disposed at an outer boundary of the source reference color boundary region to an outer boundary of the destination plausible color boundary region,

a first set of colors disposed within the source reference color boundary region to be disposed between the destination plausible color boundary region and the destination reference color boundary region, and

a second set of colors disposed within the source reference color boundary region to be disposed within the destination reference color boundary region; and

mapping, in the case that the source possible color boundary region is equal to the source plausible color boundary region which is equal to the source reference color boundary region, and the destination possible color boundary region is equal to the destination plausible color boundary region which is equal to the destination reference color boundary region,

all colors disposed within the source reference color boundary region to be disposed within the destination reference color boundary region.