US 12,081,763 B2
Image coding method and device on basis of wide-angle intra prediction and transform
Moonmo Koo, Seoul (KR); Jaehyun Lim, Seoul (KR); Junghak Nam, Seoul (KR); and Seunghwan Kim, Seoul (KR)
Assigned to LG ELECTRONICS INC., Seoul (KR)
Filed by LG ELECTRONICS INC., Seoul (KR)
Filed on Feb. 14, 2023, as Appl. No. 18/109,531.
Application 18/109,531 is a continuation of application No. 17/610,985, granted, now 11,641,471, previously published as PCT/KR2020/006827, filed on May 27, 2020.
Claims priority of provisional application 62/856,134, filed on Jun. 2, 2019.
Claims priority of provisional application 62/853,689, filed on May 28, 2019.
Claims priority of provisional application 62/853,155, filed on May 27, 2019.
Prior Publication US 2023/0199189 A1, Jun. 22, 2023
This patent is subject to a terminal disclaimer.
Int. Cl. H04N 19/132 (2014.01); H04N 19/159 (2014.01); H04N 19/176 (2014.01); H04N 19/18 (2014.01)
CPC H04N 19/132 (2014.11) [H04N 19/159 (2014.11); H04N 19/176 (2014.11); H04N 19/18 (2014.11)] 6 Claims
OG exemplary drawing
 
1. An image decoding method performed by a decoding apparatus, comprising:
obtaining intra prediction mode information and a low-frequency non-separable transform (LFNST) index from a bitstream;
deriving an intra prediction mode for a current block based on the intra prediction mode information;
derives prediction samples for the current block based on the intra prediction mode;
performing an LFNST to derive transform coefficients; and
deriving residual samples for the current block based on the transform coefficients,
wherein performing the LFNST comprising:
performing a wide-angle intra prediction mode mapping process based on a width of the current block being not equal to a height of the current block;
determining an LFNST set among four LFNST sets based on a modified intra prediction mode by the wide-angle intra prediction mode mapping process, the LFNST set comprising LFNST matrices;
selecting one of the LFNST matrices based on the determined LFNST set and the LFNST index; and
performing a matrix operation based on the one of the LFNST matrices,
wherein the intra prediction mode information indicates any one of a planar mode (0), a DC mode (1), and directional modes (2 to 66),
wherein the modified intra prediction mode is derived as any one intra prediction mode in a range from −1 to −14 based on the height of the current block being greater than the width of the current block, and
wherein an LFNST set for intra prediction modes in a range from −1 to −14 is a same as an LFNST set for intra prediction modes in a range from 2 to 12.