Patent ID: 11882310
Assignee: LG ELECTRONICS INC.
Field: Audio-visual technology (Electrical engineering)
Classification: CPC H | IPC H

Claim 0:
1. A method for decoding an image signal by an apparatus, comprising:
determining whether a non-separable transform is applied for a current block, based on a non-separable transform index obtained from a bitstream;
based on the non-separable transform being determined to be applied for the current block, determining a non-separable transform set index indicating a non-separable transform set for the current block from among four predetermined non-separable transform sets based on an intra prediction mode of the current block;
determining a transform kernel included in the non-separable transform set indicated by the non-separable transform set index as a non-separable transform matrix for the current block; and
performing secondary inverse transform for the current block based on the non-separable transform matrix,
wherein the non-separable transform matrix is applied for R coefficients included in the current block having a square shape to generate N transformed coefficients, R being smaller than N, N being equal to a total number of coefficients for which the non-separable transform matrix is applied in the current block.