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

Claim 8:
9. A method for encoding an image signal by an apparatus, comprising:
determining whether a non-separable transform is applied for a current block, a non-separable transform index indicating a result of the determination is encoded into a bitstream;
based on the non-separable transform being determined to be applied for the current block, determining 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, each of the four predetermined non-separable transform sets consists of two transform kernels;
determining a transform kernel included in the non-separable transform set as a non-separable transform matrix for the current block; and
performing secondary transform for the current block based on the non-separable transform matrix,
wherein a non-separable transform set index indicating the non-separable transform set from among predetermined non-separable transform sets is encoded into the bitstream, and
wherein the non-separable transform matrix is applied for N coefficients included in the current block having a square shape to generate R 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.