Method and apparatus for color difference transform
AssigneeWarner Bros. Entertainment Inc.
InventorMichael D. Smith
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Abstract
Efficient image compression for video data characterized by a non-neutral dominant white point is achieved by transforming the input video signal into a de-correlated video signal based on a color difference encoding transform, wherein the color difference encoding transform is adapted based on the dominant white point using an algorithm. The adapting algorithm is designed for optimizing low-entropy output when the white point is other than a neutral or equal-energy value. Decompression is handled conversely.
Claims23
A method for encoding a video signal, the method comprising:
- transforming, by a processor executing a color difference encoding transform, an input video signal encoded by tri-stimulus luminance and chromacity values of a color space and having video frames characterized by a dominant white point into a de-correlated video signal encoded by modified luminance and color difference values;
- adapting the color difference encoding transform at least in part by adapting calculation of the color difference values based on the dominant white point and
- outputting the de-correlated video signal, based on the adapting.
An apparatus comprising a processor coupled to a memory, the memory holding instructions for:
- transforming, by a color difference encoding transform, an input video signal encoded by tri-stimulus luminance and chromacity values of a color space and having video frames characterized by a dominant white point into a de-correlated video signal encoded by modified luminance and color difference values;
- adapting the color difference encoding transform at least in part by adapting calculation of the color difference values based on the dominant white point;
- and
- outputting the de-correlated video signal, based on the adapting.
A method for decoding a video signal, the method comprising:
- transforming, by a processor executing a color difference decoding transform, an input de-correlated video signal encoded by modified luminance and color difference values of a color space and having video frames characterized by a dominant white point into a correlated video signal encoded by original tri-stimulus luminance and chromaticity values;
- adapting the color difference decoding transform at least in part by adapting calculation of the chromaticity values based on the dominant white point;
- and
- outputting the correlated video signal.
An apparatus comprising a processor coupled to a memory, the memory holding instructions for:
- transforming, by a color difference decoding transform, an input de-correlated video signal encoded by modified luminance and color difference values of a color space and having video frames characterized by a dominant white point into a correlated video signal encoded by original tri-stimulus luminance and chromaticity values;
- adapting the color difference decoding transform based on the dominant white point at least in part by adapting calculation of the chromaticity values;
- and
- outputting the correlated video signal.
Dependencies are inferred from the claim text.