US 12,143,585 B2
Video coding method based on secondary transform, and device therefor
Moonmo Koo, Seoul (KR); Seunghwan Kim, Seoul (KR); Mehdi Salehifar, Seoul (KR); and Jaehyun Lim, Seoul (KR)
Assigned to LG ELECTRONICS INC., Seoul (KR)
Filed by LG Electronics Inc., Seoul (KR)
Filed on Jun. 10, 2021, as Appl. No. 17/344,410.
Application 17/344,410 is a continuation of application No. PCT/KR2020/000130, filed on Jan. 3, 2020.
Claims priority of provisional application 62/788,961, filed on Jan. 7, 2019.
Prior Publication US 2022/0103824 A1, Mar. 31, 2022
Int. Cl. H04N 19/122 (2014.01); H04N 19/11 (2014.01); H04N 19/132 (2014.01); H04N 19/159 (2014.01); H04N 19/176 (2014.01); H04N 19/18 (2014.01); H04N 19/46 (2014.01)
CPC H04N 19/122 (2014.11) [H04N 19/11 (2014.11); H04N 19/132 (2014.11); H04N 19/159 (2014.11); H04N 19/176 (2014.11); H04N 19/18 (2014.11); H04N 19/46 (2014.11)] 3 Claims
OG exemplary drawing
 
1. An image decoding method performed by a decoding apparatus, the method comprising:
deriving transform coefficients through dequantization based on quantized transform coefficients for a target block;
deriving modified transform coefficients based on an inverse non-separable transform using a transform kernel matrix for the transform coefficients; and
deriving residual samples for the target block based on an inverse primary transform for the modified transform coefficients,
wherein the deriving the modified transform coefficients comprises:
deriving flag information related to whether or not a transform index is received, wherein the transform index is related to whether the inverse non-separable transform is applied to the target block and which one of transform kernel matrices is applied to the target block;
deriving the transform index based on the flag information; and
performing a matrix operation of specific transform coefficients in the target block and the transform kernel matrix related to the transform index,
wherein the flag information is signaled in a sequence parameter set, and the transform index is present in a coding unit syntax,
wherein based on the inverse non-separable transform being applied to 8×8 area of the target block, 48 modified transform coefficients are derived by performing the matrix operation with 16 specific transform coefficients in the target block,
wherein the 16 specific transform coefficients for the matrix operation are ordered in a diagonal scan order from the top-left 4×4 area of the 8×8 area of the target block,
wherein based on an intra prediction mode for the target block being less than or equal to mode 34, the 48 modified transform coefficients are arranged in a horizontal scan order in an area excluding the bottom-right 4×4 area in the 8×8 area of the target block, and
wherein based on the intra prediction mode for the target block being more than the mode 34, the 48 modified transform coefficients are arranged in a vertical scan order in the area excluding the bottom-right 4×4 area in the 8×8 area of the target block.