Color metadata for a downlink data channel
View Patent ↗The present invention provides a method and system for determining and providing color metadata for a downlink data channel. In accordance with the present invention color metadata is determined such that gamut mapping is defined by a transmitted source gamut which enables adapted mapping that preserves saturation and contrast levels of the source for a downlink data channel. The metadata is then provided to a downlink data channel for color management.
1. A method for gamut mapping a color gamut of content of a source, comprising:
determining metadata describing said color gamut of content of a source;
communicating said metadata to a data channel for use in said gamut mapping that preserves saturation and contrast levels of said source; and
performing said gamut mapping based on a color space gamut defined using said color gamut of said source;
wherein the color gamut of said source is defined by a set of vertices with indexed facets in a chosen color space;
wherein a size, measured in bits, of gamut vertices and gamut facets fields of the color space gamut definition is characterized according to an equation, which follows:
S= 3 N V N+ 3 N F ┌ld ( N V )┐,
wherein, ┌*┐ depicts an operation that rounds to the next upper integer, Id depicts a logarithm to the base of 2, N represents color precision of the chosen color space, N v represents a number of vertices, and N F represents a number of facets.
2. The method of claim 1 , wherein said color space gamut is defined in xvYCC space.
3. The method of claim 1 , wherein said content comprises a three color primary.
4. The method of claim 1 , wherein the color gamut of said source is smooth and a sampling scheme is implemented to define the color space gamut.
5. The method of claim 1 , wherein the color gamut of said source is regular and a regular sampling scheme is implemented to define the color space gamut.
6. The method of claim 1 , wherein an indexed facet set is implemented to define the color space gamut.
7. The method of claim 1 , wherein said color space gamut definition comprises a gamut boundary description.
8. The method of claim 7 wherein said gamut boundary description comprises a cuboid.
9. The method of claim 1 , wherein a precision of said chosen color space is defined by at least one of 3×8 bit, 3×10 bit, and 3×12 bit.
10. The method of claim 1 , wherein said color space gamut is defined in CIE L*a*b* space.
11. The method of claim 1 , wherein 3N v N corresponds to the size for gamut vertices, and 3N F ┌ld(N v )┐ corresponds to the size for gamut facets.
12. A method, at a downlink data channel, for performing gamut mapping of a content of a source, comprising:
receiving metadata describing the color gamut of content of the source;
using said received metadata for an adaptation of said gamut mapping that preserves saturation and contrast levels of the source; and
performing said gamut mapping;
wherein said adaptation comprises defining a color space gamut using the color gamut of said source; and using said defined color space gamut in said gamut mapping;
wherein the color gamut of said source is defined by a set of vertices with indexed facets in a chosen color space; and a size, measured in bits, of gamut vertices and gamut facets fields of the color space gamut definition is characterized according to an equation, which follows:
S= 3 N V N+ 3 N F ┌ld ( N V )┐.
wherein, ┌*┐ depicts an operation that rounds to the next upper integer, Id depicts a logarithm to the base of 2, N represents color precision of the chosen color space, N v represents number of vertices, and N F represents number of facets.
13. The method of claim 12 , wherein said color space gamut definition comprises a gamut boundary description.
14. The method of claim 13 , wherein said gamut boundary description comprises a cuboid.
15. The method of claim 12 , wherein a precision of said chosen color space is defined by at least one of 3×8 bit, 3×10 bit, and 3×12 bit.
16. The method of claim 12 , wherein 3N V N corresponds to the size for gamut vertices, and 3N F ┌ld(N v )┐ corresponds to the size for gamut facets.
17. A method for gamut mapping a color gamut of content of a source, comprising:
determining metadata describing a color gamut boundary of content of a source;
communicating the metadata to a sink, via a data channel, for use in the gamut mapping; and
performing the gamut mapping based on the metadata for display of the content at the sink, wherein the color gamut is described using a set of vertices with facets in a chosen color space, and further wherein the metadata describing the color gamut boundary of the source comprises a set of data including:
color space indicator that is indicative of the color space associated with the gamut boundary description;
number of vertices indicator indicative of number of vertices associated with the gamut boundary description;
gamut vertices data associated with the gamut boundary description;
facet mode indicator that is indicative of whether facet data is included in the gamut boundary description;
number of facets indicator indicative of number of facets associated with the gamut boundary description; and
gamut facet data associated with the gamut boundary description, and in accordance with the facet mode indicator.
18. The method for gamut mapping according to claim 17 , wherein the set of data further includes a color precision indicator that is indicative of a color space precision associated with the gamut boundary description.
19. The method for gamut mapping according to claim 18 , wherein the color precision indicator indicates that the color space precision is one of 8 bit, 10, and 12 bit precision.