US 12,439,096 B2
Context-based reshaping algorithms for encoding video data
Neeraj J. Gadgil, Pune (IN); and Guan-Ming Su, Freemont, CA (US)
Assigned to Dolby Laboratories Licensing Corporation, San Francisco, CA (US)
Appl. No. 18/702,730
Filed by Dolby Laboratories Licensing Corporation, San Francisco, CA (US)
PCT Filed Oct. 20, 2022, PCT No. PCT/US2022/047226
§ 371(c)(1), (2) Date Apr. 18, 2024,
PCT Pub. No. WO2023/069585, PCT Pub. Date Apr. 27, 2023.
Claims priority of provisional application 63/270,097, filed on Oct. 21, 2021.
Claims priority of application No. 21203845 (EP), filed on Oct. 21, 2021.
Prior Publication US 2025/0234051 A1, Jul. 17, 2025
Int. Cl. H04N 19/98 (2014.01); G06F 17/18 (2006.01); H04N 19/172 (2014.01)
CPC H04N 19/98 (2014.11) [G06F 17/18 (2013.01); H04N 19/172 (2014.11)] 13 Claims
OG exemplary drawing
 
1. A video delivery system for encoding of HDR video data, the delivery system comprising:
a processor to perform encoding of HDR video data, the processor configured to:
receive the HDR video data, the HDR video data composed of a plurality of image frames, each image frame including a plurality of pixel blocks;
compute, for each pixel block k, a mean for luma pixel values included in the pixel block k;
compute, for each pixel block k, a standard deviation for luma pixel values included in the pixel block k;
determine, for each pixel block k, a block-mean bin index bk, wherein the entire HDR luma codeword range is divided into NB non-overlapping luma bins, wherein each luma bin b represents a corresponding discrete luma codeword range, and wherein the block-mean bin index bk is the floor function of multiplying the mean for luma pixel values included in the pixel block k with NB;
compute, for each luma bin b, a block histogram by counting a number of pixels that have a block-mean bin index bk equal to b;
compute, for each luma bin b, a block standard deviation by averaging standard deviation over all pixel blocks that have a block-mean bin index bk equal to b;
determine, for each luma bin b, a banding risk value, wherein the banding risk value is determined using a multiplicative combination of the block histogram and the block standard deviation of the respective luma bin;
determine a Gaussian function defined by Gaussian function parameters including a mean value and a width value of a corresponding Gaussian distribution, wherein the width value is the reciprocal of the doubled square of the standard deviation of the Gaussian distribution, wherein the mean value of the Gaussian function parameters is set to the maximum banding risk value across all luma bins;
generate a differential reshaping function using the Gaussian function parameters, the differential reshaping function specifying the amount of increment to the next lower input value of the differential reshaping function;
compute a luma-based forward reshaping function based on the differential reshaping function, wherein the luma-based forward reshaping function is a monotonically non-decreasing function that transfers a higher bit-depth codeword to a lower bit-depth by using the differential reshaping function; and
generate an output image for each image frame by applying the luma-based forward reshaping function to the respective image frame.