# US 2018/0324329 A1 · Hue changing color gamut mapping

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- Number: US 2018/0324329 A1
- Document ID: US20180324329A1
- Status: Published application
- Kind: A1
- Application number: 15/739,769
- Filed: 2016-06-08
- Published: 2018-11-08
- Earliest claimed: 2015-06-25
- Assignees: Thomson Licensing
- Applicants: THOMSON Licensing
- Inventors: Cedric THEBAULT; Jurgen STAUDER; Anita ORHAND
- Web page: https://patentgrep.com/patent/US20180324329A1

## CPC

- H04N 1/6066: {dependent on the gamut of the image to be reproduced}
- G06T 3/4007: based on interpolation, e.g. bilinear interpolation (image demosaicing G06T3/4015; edge-driven or edge-based scaling G06T3/403)
- H04N 1/6058: {Reduction of colour to a range of reproducible colours, e.g. to ink- reproducible colour gamut}
- H04N 1/6075: {Corrections to the hue}
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION
- G06T: IMAGE DATA PROCESSING OR GENERATION, IN GENERAL

## Abstract

An aspect of present principles is directed to methods and systems for gamut mapping source colors into target colors from a source color gamut towards a target color gamut. A difference may be determined source specific colors and corresponding target specific colors. A source hue of the source specific colors is adaptively changed towards a target hue of the corresponding target specific colors based on the difference to determine mapped specific colors. Color gamut mapping is performed for the source colors of the source color gamut towards the target color gamut based on the mapped specific colors. The specific colors are selected from primary colors, secondary colors, a group of primary colors and secondary colors. The difference is based on at least one selected from the group of hue, saturation and lightness of the source specific colors and the corresponding target specific colors.

## Claims

### Claim at position 1

1-15. (canceled)

### Claim 16

A method for gamut mapping source colors into target colors from a source color gamut towards a target color gamut, comprising:
adaptively changing a source hue of at least one source specific color towards a target hue of a corresponding target specific color based on a difference a between a hue of this source specific color and a hue of this target specific color to determine a mapped specific color;
performing color gamut mapping for the source colors of the source color gamut towards the target color gamut based on the mapped specific colors,
wherein the specific colors are at least one selected from a group of primary colors, secondary colors, a group of primary colors and secondary colors,
wherein said changing of hue is represented by a hue rotation angle
θ
=
α
*
cos

(
γ
-
β
2
)
in a hue-chroma plane having an origin O defined by a zero chroma value in this plane, where, if said at least one source specific color and corresponding target specific color are represented respectively by (Ps) and (Pt) in said hue-chroma plane, α=, β=, and γ=.

### Claim 17 (depends on 16)

The method for gamut mapping according to claim 16, further comprising determining the hue of at least one non-specific color by interpolation of changed hue values of the mapped specific source colors.

### Claim 18 (depends on 17)

The method for gamut mapping according to claim 17, wherein said changed hue values used for said interpolation are adjacent to said at least one non-specific color.

### Claim 19

A system for gamut mapping source colors into target colors from a source color gamut towards a target color gamut, comprising:
a processor configured to adaptively change a source hue of at least one source specific color towards a target hue of a corresponding target specific color based on a difference a between a hue of this source specific color and a hue of this target specific color to determine a mapped specific color and to perform color gamut mapping for the source colors of the source color gamut towards the target color gamut based on the mapped specific colors,
wherein the specific colors are at least one selected from a group of primary colors, secondary colors, a group of primary colors and secondary colors,
wherein said changing of hue is represented by a hue rotation angle
θ
=
α
*
cos

(
γ
-
β
2
)
in a hue-chroma plane having an origin O defined by a zero chroma value in this plane,
where, if said at least one source specific color and corresponding target specific color are represented respectively by (Ps) and (Pt) in said hue-chroma plane, α=, β=, and γ=.

### Claim 20 (depends on 19)

The system for gamut mapping according to claim 19, wherein the processor is further configured to determine the hue of at least one non-specific color by interpolation of changed hue values of the mapped specific source colors.

### Claim 21 (depends on 20)

A system for gamut mapping according to claim 20, wherein said changed hue values used for said interpolation are adjacent to said at least one non-specific color.

### Claim 22

A non-transitory computer readable storage medium comprising a computer program including a set of instructions executable by a processor, the instructions comprising:
adaptively changing a source hue of at least one source specific color towards a target hue of a corresponding target specific color based on a difference a between a hue of this source specific color and a hue of this target specific color to determine a mapped specific color;
performing color gamut mapping for the source colors of the source color gamut towards the target color gamut based on the mapped specific colors,
wherein the specific colors are at least one selected from a group of primary colors, secondary colors, a group of primary colors and secondary colors,
wherein said changing of hue is represented by a hue rotation angle
θ
=
α
*
cos

(
γ
-
β
2
)
in a hue-chroma plane having an origin O defined by a zero chroma value in this plane, where, if said at least one source specific color and corresponding target specific color are represented respectively by (Ps) and (Pt) in said hue-chroma plane, α=, β=, and γ=.

### Claim 23 (depends on 22)

The non-transitory computer readable storage medium according to claim 22, wherein the instructions comprise:
determining the hue of at least one non-specific color by interpolation of changed hue values of the mapped specific source colors.

### Claim 24 (depends on 23)

The non-transitory computer readable storage medium according to claim 23, wherein said changed hue values used for said interpolation are adjacent to said at least one non-specific color.