Image encoding/decoding method and apparatus for signaling residual coding method used for encoding block to which BDPCM is applied, and method for transmitting bitstream

An image decoding apparatus comprising:

• a memory;
• and
• at least one processor,
• wherein the at least one processor is configured to:
• determine a residual coding method of a current transform block corresponding to a current coding block;
• reconstruct residual information of the current transform block based on the determined residual coding method;
• and
• reconstruct the current transform block based on the residual information,
• wherein the residual coding method is determined based on a transform skip flag specifying whether transform of the current transform block is skipped,
• wherein the transform skip flag is obtained from a bitstream based on BDPCM being applied to the current coding block and transform skip residual coding being not able to be performed on the current coding block,
• wherein, based on the transform skip flag being not obtained from the bitstream, a value of the transform skip flag is derived as a first value specifying that transform of the current transform block is skipped based on both BDPCM being applied to the current coding block and transform skip residual coding being able to be performed on the current coding block, and
• wherein, based on the transform skip flag being not obtained from the bitstream, a value of the transform skip flag is derived as a second value specifying that transform of the current transform block is not skipped based on BDPCM being not applied to the current coding block or transform skip residual coding being not able to be performed on the current coding block.

An image encoding method performed by an image encoding apparatus, the image encoding method comprising:

• determining a residual coding method of a current transform block corresponding to a current coding block;
• determining residual information of the current transform block based on the determined residual coding method;
• and
• encoding the current transform block based on the residual information,
• wherein the residual coding method is determined based on whether transform of the current transform block is skipped, whether transform of the current transform block being encoded into a bitstream using a transform skip flag,
• wherein the transform skip flag is encoded into the bitstream based on BDPCM being applied to the current coding block and transform skip residual coding being not able to be performed on the current coding block,
• wherein, based on the transform skip flag being not encoded into the bitstream, a value of the transform skip flag is derived as a first value specifying that transform of the current transform block is skipped based on both BDPCM being applied to the current coding block and transform skip residual coding being able to be performed on the current coding block, and
• wherein, based on the transform skip flag being not encoded into the bitstream, a value of the transform skip flag is derived as a second value specifying that transform of the current transform block is not skipped based on BDPCM being not applied to the current coding block or transform skip residual coding being not able to be performed on the current coding block.