Method for encoding/decoding image signal, and device therefor

A method of decoding a video, the method comprising:

• deriving a residual coefficient of a current block;
• dequantizing the residual coefficient;
• deriving a joint residual sample by performing an inverse transform for the dequantized residual coefficient;
• determining one of a plurality of residual sample decoding mode candidates as a residual sample decoding mode for the current block;
• and
• deriving a first residual sample for a first chroma component and a second residual sample for a second chroma component based on the joint residual sample,
• wherein the first residual sample is derived based on a first derivation method when a first residual sample decoding mode is selected among the plurality of residual sample decoding mode candidates,
• wherein the first residual sample is derived based on a second derivation method when a second residual sample decoding mode is selected among the plurality of residual sample decoding mode candidates, wherein the first derivation method is different from the second derivation method,
• wherein when the first residual sample decoding mode is selected, the first residual sample is derived to be the same as the joint residual sample,
• wherein when the second residual sample decoding mode is selected, the first residual sample is derived to have a sign opposite to the joint residual sample or by scaling the joint residual sample.

A system comprising:

• one or more processors;
• and
• one or more non-transitory computer readable media storing instructions that, when executed by the one or more processors, cause the one or more processors to perform operations comprising:
• deriving a residual coefficient of a current block;
• dequantizing the residual coefficient;
• deriving a joint residual sample by performing an inverse transform for the dequantized residual coefficient;
• determining one of a plurality of residual sample decoding mode candidates as a residual sample decoding mode for the current block;
• and
• deriving a first residual sample for a first chroma component and a second residual sample for a second chroma component based on the joint residual sample,
• wherein the first residual sample is derived based on a first derivation method when a first residual sample decoding mode is selected among the plurality of residual sample decoding mode candidates,
• wherein the first residual sample is derived based on a second derivation method when a second residual sample decoding mode is selected among the plurality of residual sample decoding mode candidates, wherein the first derivation method is different from the second derivation method,
• wherein when the first residual sample decoding mode is selected, the first residual sample is derived to be the same as the joint residual sample,
• wherein when the second residual sample decoding mode is selected, the first residual sample is derived to have a sign opposite to the joint residual sample or by scaling the joint residual sample.

One or more non-transitory computer readable media storing instructions that, when executed by one or more processors, cause the one or more processors to perform operations comprising:

• deriving a residual coefficient of a current block;
• dequantizing the residual coefficient;
• deriving a joint residual sample by performing an inverse transform for the dequantized residual coefficient;
• determining one of a plurality of residual sample decoding mode candidates as a residual sample decoding mode for the current block;
• and
• deriving a first residual sample for a first chroma component and a second residual sample for a second chroma component based on the joint residual sample,
• wherein the first residual sample is derived based on a first derivation method when a first residual sample decoding mode is selected among the plurality of residual sample decoding mode candidates,
• wherein the first residual sample is derived based on a second derivation method when a second residual sample decoding mode is selected among the plurality of residual sample decoding mode candidates, wherein the first derivation method is different from the second derivation method,
• wherein when the first residual sample decoding mode is selected, the first residual sample is derived to be the same as the joint residual sample,
• wherein when the second residual sample decoding mode is selected, the first residual sample is derived to have a sign opposite to the joint residual sample or by scaling the joint residual sample.