Patent ID: 11943445
Assignee: LG ELECTRONICS INC.
Field: Audio-visual technology (Electrical engineering)
Classification: CPC H | IPC H

Claim 0:
1. An image decoding method performed by a decoding apparatus, the method comprising:
receiving image information comprising residual information and an LFNST index from a bitstream;
deriving transform coefficients by performing dequantization based on the residual information;
deriving a flag variable array related to whether an LFNST is applied to a current block based on the LFNST index; and
performing the LFNST based on the flag variable array and the transform coefficients,
wherein the flag variable array is defined as a one-dimensional array,
wherein flag variables included in the flag variable array are derived for each color component of the current block,
wherein the flag variable array includes a first flag variable for a luma component, a second flag variable for a Cb component and a third flag variable for a Cr component,
wherein the first flag variable is set to 1 and the second flag variable and the third flag variable are set to 0, based on a tree type of the current block being a single tree and a value of the LFNST index being greater than 0,
wherein the first flag variable is set to 1 based on a tree type of the current block being a dual tree luma and the value of the LFNST index being greater than 0,
wherein the second flag variable and the third flag variable are set to 1 based on a tree type of the current block being a dual tree chroma and a value of the LFNST index being greater than 0,
wherein the dequantization is performed based on a scaling list, and
wherein whether to apply the scaling list for the each color component of the current block is determined based on a value of a flag variable allocated for the each color component in the flag variable array.