Patent ID: 11962779
Assignee: LG ELECTRONICS INC.
Field: Audio-visual technology (Electrical engineering)
Classification: CPC H | IPC H

Claim 5:
6. An image encoding method performed by an image encoding apparatus, the method comprising:
deriving prediction samples for a current block;
deriving residual samples for the current block based on the prediction samples;
deriving transform coefficients for the current block based on a primary transform for the residual samples;
constructing image information to derive flag information indicating whether a significant coefficient exists in a second region other than a top-left first region of the current block; and
encoding residual information derived based on the transform coefficients for the current block and a multiple transform selection (MTS) index based on the flag information indicating that no significant coefficient exists in the second region,
wherein the constructing of the image information comprises:
parsing a flag related to whether the significant coefficient is present in a scan subblock by scanning the scan subblock in a preset scan subblock unit according to an reverse diagonal scan order;
determining whether the scan subblock belongs to the second region based on a value of the flag being 1; and
determining whether a color index of the current block indicates a luma component based on the scan subblock belonging to the second region, and
wherein the flag information specifies that the significant coefficient is present in the second region based on the color index indicating the luma component.