Tone and gamut mapping methods and apparatus

1. A method for mapping pixel data, the method comprising:

comparing location information corresponding to the pixel data to a set of one or more special locations within an image frame, said special location being associated with a special mapping algorithm;

comparing color coordinates for the pixel data to a set of one or more reserved colors, said reserved color being designated as not affected by mapping transformations;

comparing color coordinates of the pixel data to a set of one or more special color regions, said special color region being associated with a color-specific mapping; and

generating metadata based on tone or gamut parameters comprising the special locations, the reserved colors and the special color regions for the pixel data as adjusted by a color grader.

2. A method according to claim 1 comprising comparing color coordinates for the pixel data to a set of one or more reserved colors and, in response to the color coordinates matching one of the set of reserved colors, inhibiting gamut mapping of the pixel data.

3. A method according to claim 2 comprising receiving and storing metadata comprising information specifying the set of one or more reserved colors.

4. A method according to claim 3 , wherein receiving the metadata comprises extracting the metadata from a signal or file containing the pixel data.

5. A method according to claim 2 , the method further comprising the steps of:

receiving statistical information regarding luminance or chrominance values of the pixel data; and

mapping the pixel data to mapped pixel data by a mapping based in part on the statistical information.

6. A method according to claim 1 comprising comparing color coordinates of the pixel data to a set of one or more special color regions and, in response to the color coordinates corresponding to one of the set of special color regions, selecting a color-specific map and mapping the pixel data according to the color-specific map.

7. A method according to claim 6 comprising receiving and storing metadata comprising information specifying the set of one or more special color regions.

8. A method according to claim 7 wherein receiving the metadata comprises extracting the metadata from a signal or file containing the pixel data.

9. A method according to claim 8 , the method further comprising the steps of:

receiving statistical information regarding luminance or chrominance values of the pixel data; and

mapping the pixel data to mapped pixel data by a mapping based in part on the statistical information.

10. A method according to claim 1 comprising receiving and storing metadata comprising information specifying the set of one or more special locations.

11. A method according to claim 10 , wherein receiving the metadata comprises extracting the metadata from a signal or file containing the pixel data.

12. A method according to claim 1 wherein the special locations comprise special locations of a plurality of types and the method comprises selecting the special mapping algorithm from a plurality of predetermined special algorithms based upon the type of the special location matched by the location information.

13. A method according to claim 12 wherein the type of the special location comprises one of: emissive light source and reflective light source.

14. A method according to claim 1 , the method comprising:

receiving statistical information regarding luminance or chrominance values of the pixel data; and

mapping the pixel data to mapped pixel data by a mapping based in part on the statistical information.

15. A method according to claim 14 wherein the statistical information comprises a histogram of the number of pixels for each color channel having a luminance value within a luminance range associated with one of a plurality of predefined histogram buckets.

16. A method according to claim 1 comprising:

in response to the location information matching one of the set of one or more special locations, performing one or both of tone and gamut mapping the pixel data according to a special mapping algorithm.

17. Image processing apparatus comprising:

a color grading processor configured to:

receive pixel data for an image;

generate metadata based on tone or gamut parameters selectable by a color grader; wherein the parameters comprise: one or more special locations within an image frame, said special location being associated with a special mapping algorithm; one or more reserved colors, said reserved color being designated as not affected by mapping transformations; and one or more special color regions, said special color region being associated with a color-specific mapping.

18. Image processing apparatus according to claim 17 comprising a buffer or memory containing a set of special locations and a first comparison unit configured to compare the location information of the pixel data to locations in the set of special locations.

19. Image processing apparatus according to claim 18 comprising a buffer or memory containing information specifying one or more special colors and a second comparison unit configured to compare color coordinates of the pixel data to the set of special colors.

20. Image processing apparatus according to claim 17 comprising:

a plurality of parallel pipelines each configured to map pixel data to mapped pixel data according to a corresponding mapping algorithm;

algorithm selection logic configured to select one of the plurality of pipelines for mapping specific pixel data based at least in part on location information corresponding to the specific pixel data.

21. A method for mapping tone, gamut or both tone and gamut of pixel data in image data, the method comprising:

receiving pixel data for an image at a mapping apparatus;

receiving metadata at the mapping apparatus, the metadata comprising:

information specifying a set of one or more special locations within an image frame, said special location being associated with a special mapping algorithm;

information specifying a set of one or more reserved colors, said reserved color being designated as not affected by mapping transformations; and

information specifying a set of one or more special color regions, said special color region being associated with a color-specific mapping;

mapping the pixel data to mapped pixel data according to an algorithm based at least in part on mapping parameters determined from the metadata;

generating the metadata based on tone or gamut parameters for the pixel data as adjusted by a color grader.

22. A method according to claim 21 , comprising:

encoding the metadata in image data for transmission to the mapping apparatus.