Residual signal encoding/decoding method and apparatus employing intra sub-partitions (ISP), 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 whether a prediction mode of a current block is an intra prediction mode, based on information on the prediction mode of the current block;
• determine whether a transform mode of the current block is a transform skip mode;
• determine whether an intra prediction technique of the current block is intra sub-partitions (ISP), based on the prediction mode of the current block being the intra prediction mode;
• and
• generate a transform coefficient block of the current block, based on the transform mode of the current block and whether the intra prediction technique of the current block is the ISP,
• wherein the generating the transform coefficient block comprises the at least one processor configured to:
• split the transform coefficient block of the current block into transform subblocks having a predetermined size;
• and
• reconstruct a transform coefficient included in a transform subblock by decoding information on the transform coefficient included in the transform subblock,
• wherein the reconstructing the transform coefficient included in the transform subblock is performed based on first information specifying whether a non-zero transform coefficient is included in the transform subblock, and
• wherein, based on the transform mode of the current block being the transform skip mode and the intra prediction technique of the current block being the ISP, parsing of the first information is skipped, and the first information is set to specify that the transform subblock includes the non-zero transform coefficient.

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

• determining whether a prediction mode of a current block is an intra prediction mode;
• determining whether a transform mode of the current block is a transform skip mode;
• determining whether an intra prediction technique of the current block is intra sub-partitions (ISP), based on the prediction mode of the current block being the intra prediction mode;
• and
• encoding information on a transform coefficient of the current block, based on the transform mode of the current block and whether the intra prediction technique of the current block is the ISP,
• wherein the encoding the information on the transform coefficient comprises:
• splitting a transform coefficient block of the current block into transform subblocks having a predetermined size;
• and
• encoding a transform coefficient included in a transform subblock,
• wherein the encoding the transform coefficient included in the transform subblock is performed based on first information specifying whether a non-zero transform coefficient is included in the transform subblock, and
• wherein, based on the transform mode of the current block being the transform skip mode and the intra prediction technique of the current block being the ISP, encoding of the first information is skipped, and the first information is set to specify that the transform subblock includes the non-zero transform coefficient.