US 12,262,015 B2
Transform-based image coding method and device
Moonmo Koo, Seoul (KR); Jaehyun Lim, Seoul (KR); and Seunghwan Kim, Seoul (KR)
Assigned to LG Electronics Inc., Seoul (KR)
Appl. No. 17/762,150
Filed by LG ELECTRONICS INC., Seoul (KR)
PCT Filed Sep. 21, 2020, PCT No. PCT/KR2020/012707
§ 371(c)(1), (2) Date Mar. 21, 2022,
PCT Pub. No. WO2021/054798, PCT Pub. Date Mar. 25, 2021.
Claims priority of provisional application 62/904,636, filed on Sep. 23, 2019.
Claims priority of provisional application 62/903,823, filed on Sep. 21, 2019.
Prior Publication US 2022/0417518 A1, Dec. 29, 2022
Int. Cl. H04N 19/18 (2014.01); H04N 19/119 (2014.01); H04N 19/132 (2014.01); H04N 19/176 (2014.01)
CPC H04N 19/132 (2014.11) [H04N 19/119 (2014.11); H04N 19/176 (2014.11); H04N 19/18 (2014.11)] 3 Claims
OG exemplary drawing
 
1. An image decoding method performed by a decoding apparatus, the method comprising:
obtaining, from a bitstream, residual information and a low-frequency non-separable transform (LFNST) index;
deriving transform coefficients for a current block based on the residual information;
deriving residual samples for the current block by applying an inverse primary transform to the transform coefficients using transform kernels for vertical and horizontal; and
generating a reconstructed picture based on the residual samples,
wherein based on the current block being divided into sub-partition blocks as an intra sub-partitions (ISP) is applied and the LFNST index being equal to 0, the transform kernel for vertical is determined by checking a vertical length of a sub-partition block divided from the current block, and the transform kernel for horizontal is determined by checking a horizontal length of the sub-partition block, and
wherein based on the current block being divided into the sub-partition blocks as the ISP is applied and the LFNST index being greater than 0, the transform kernels for vertical and horizontal are respectively determined as DCT-2.