ACT RESIDUAL-BASED IMAGE OR VIDEO CODING
According to the disclosure of the present document, a residual sample can be derived by applying adaptive color transform (ACT) with respect to a current block on the basis of ACT-associated information, wherein the residual sample is derived by being clipped on the basis of a clipping boundary, wherein the clipping boundary is determined on the basis of a bit depth.
1 . An image decoding method performed by a decoding apparatus, the method comprising:
obtaining image information including prediction mode information and adaptive color transform (ACT)-related information from a bitstream;
deriving a prediction sample for a current block based on the prediction mode information;
deriving a residual sample by applying an ACT for the current block based on the ACT-related information; and
generating a reconstructed sample for the current block based on the prediction sample and the residual sample,
wherein the ACT-related information includes information on whether to apply the ACT to the current block,
wherein based on the information on whether to apply the ACT to the current block, the residual sample is derived by clipping based on a clipping range,
wherein the clipping range is determined based on a bit depth (BitDepth),
wherein the clipping range has a maximum value and a minimum value derived based on a value obtained by increasing the bit depth by 1, and
wherein the maximum value of the clipping range is equal to (1<<(BitDepth+1))−1.
2 . An image encoding method performed by an encoding apparatus, the method comprising:
generating a prediction sample for a current block;
generating prediction mode information based on the prediction sample;
generating adaptive color transform (ACT)-related information for the current block;
deriving a residual sample by applying an ACT to the current block based on the ACT-related information and the prediction sample;
generating residual information based on the residual sample; and
encoding image information including the prediction mode information, the ACT-related information and the residual information,
wherein the ACT-related information includes information on whether to apply the ACT to the current block,
wherein based on the information on whether to apply the ACT to the current block, the residual sample is derived by clipping based on a clipping range,
wherein the clipping range is determined based on a bit depth (BitDepth),
wherein the clipping range has a maximum value and a minimum value derived based on a value obtained by increasing the bit depth by 1, and
wherein the maximum value of the clipping range is equal to (1<<(BitDepth+1))−1.
3 . A non-transitory computer-readable storage medium storing a bitstream generated by the image encoding method of claim 2 .
4 . A transmission method of data for an image, the transmission method comprising:
obtaining a bitstream for the image, wherein the bitstream is generated based on generating a prediction sample for a current block, generating prediction mode information based on the prediction sample, generating adaptive color transform (ACT)-related information for the current block, deriving a residual sample by applying an ACT to the current block based on the ACT-related information and the prediction sample, generating residual information based on the residual sample, and encoding image information including the prediction mode information, the ACT-related information and the residual information; and
transmitting the data comprising the bitstream,
wherein the ACT-related information includes information on whether to apply the ACT to the current block,
wherein based on the information on whether to apply the ACT to the current block, the residual sample is derived by clipping based on a clipping range,
wherein the clipping range is determined based on a bit depth (BitDepth),
wherein the clipping range has a maximum value and a minimum value derived based on a value obtained by increasing the bit depth by 1, and
wherein the maximum value of the clipping range is equal to (1<<(BitDepth+1))−1.