Patent ID: 11949873
Assignee: LG ELECTRONICS INC.
Field: Audio-visual technology (Electrical engineering)
Classification: CPC H | IPC H

Claim 9:
10. A non-transitory computer-readable digital storage medium that stores a bitstream generated by a method, the image decoding 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 by applying an primary transform to the residual samples;
deriving residual information based on the transform coefficient of a top-left 16×16 region of the current block; and
constructing image information to parse a multiple transform selection (MTS) index indicating an primary transform kernel based on a significant coefficient being present in a second region other than the top-left 16×16 region,
wherein the constructing of the image information comprise:
encoding a flag indicating 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; and
deriving flag information indicating whether the significant coefficient is present in a second region based on (i) whether the significant coefficient is present the scan subblock, (ii) whether the scan subblock belongs to the second region other than a top-left 16×16 region of the current block, and (iii) whether a color index of the current block is 0, and
encoding the MTS index based on the flag information indicating that the significant coefficient is not present in the second region.