Patent ID: 11895416
Assignee: DOLBY LABORATORIES LICENSING CORPORATION
Field: Audio-visual technology (Electrical engineering)
Classification: CPC H  G | IPC G  H

Claim 17:
18. A method for determining a backward reshaping function, comprising:
determining a set of sample pixels from received video data;
defining, from the set of sample pixels, a first set of sample pixels according to a first electro-optical transfer function in a first color representation of a first color space;
converting the first set of sample pixels according to the first electro-optical transfer function to a second electro-optical transfer function in the first color representation of the first color space via a mapping function,
producing, from the first set of sample pixels, a second set of sample pixels according to the second electro-optical transfer function;
converting the first set of sample pixels and the second set of sample pixels from the first color representation to a second color representation of the first color space, and
determining a backward reshaping function based on the converted first set of sample pixels and the converted second set of sample pixels wherein determining the backward reshaping function includes repeatedly applying and adjusting a sample backward reshaping function so as to minimize a difference between predicted pixel values obtained by applying the sample backward reshaping function to the pixels in the converted first set of sample pixels and, and the pixels in the converted second set of sample pixels,
wherein converting the first set of sample pixels according to the first electro- optical transfer function to the second electro-optical transfer function via the mapping function includes applying a signal legalization function to the first set of sample pixels for forcing a range of the first set of sample pixels to be within a predetermined range.