Image decoding method using bdpcm and device therefor

An image decoding method, performed by a decoding apparatus, comprising:

• obtaining image information including Block-based Delta Pulse Code Modulation (BDPCM) related information for a current block;
• deriving prediction samples for a first sample and a second sample of the current block based on the BDPCM related information and a neighboring sample of the current block;
• deriving reconstructed samples for the first sample and the second sample based on the prediction samples;
• and
• storing an intra prediction mode of a prediction direction of the current block derived based on a BDPCM direction flag as an intra prediction mode of the current block,
• wherein the BDPCM related information includes the BDPCM direction flag representing the prediction direction,
• wherein based on the prediction direction being a horizontal direction, a horizontal intra prediction mode is stored as an intra prediction mode of the current block,
• wherein based on the prediction direction being a vertical direction, a vertical intra prediction mode is stored as the intra prediction mode of the current block,
• wherein the first sample is a sample in the current block adjacent to the neighboring sample, and the second sample is a sample in the current block adjacent to the first sample in the prediction direction,
• wherein the intra prediction mode stored as the intra prediction mode of the current block is used for prediction for a block coded after the current block, and
• wherein the block coded after the current block is a block within a current Coding Tree Unit (CTU) or a neighboring CTU in a current picture or a reference picture.

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

• deriving prediction samples for a first sample and a second sample of a current block based on Block-based Delta Pulse Code Modulation (BDPCM) and a neighboring sample of the current block;
• encoding a BDPCM flag representing that the BDPCM is applied to the current block and a BDPCM direction flag representing a prediction direction for the current block;
• and
• storing an intra prediction mode of the prediction direction as an intra prediction mode of the current block,
• wherein the first sample is a sample in the current block adjacent to the neighboring sample, and the second sample is a sample in the current block adjacent to the first sample in the prediction direction,
• wherein based on the prediction direction being a horizontal direction, a horizontal intra prediction mode is stored as an intra prediction mode of the current block,
• wherein based on the prediction direction being a vertical direction, a vertical intra prediction mode is stored as the intra prediction mode of the current block,
• wherein the intra prediction mode stored as the intra prediction mode of the current block is used for prediction for a block coded after the current block, and
• wherein the block coded after the current block is a block within a current Coding Tree Unit (CTU) or a neighboring CTU in a current picture or a reference picture.

A transmission method of data for image, the method comprising:

• obtaining a bitstream of video information including Block-based Delta Pulse Code Modulation (BDPCM) related information for a current block;
• and
• transmitting the data including the bitstream of the video information including the BDPCM related information,
• wherein prediction samples for a first sample and a second sample of the current block are derived based on the BDPCM related information and a neighboring sample of the current block,
• wherein an intra prediction mode of a prediction direction of the current block derived based on a BDPCM direction flag is stored as an intra prediction mode of the current block,
• wherein the BDPCM related information includes the BDPCM direction flag representing the prediction direction,
• wherein based on the prediction direction being a horizontal direction, a horizontal intra prediction mode is stored as an intra prediction mode of the current block,
• wherein based on the prediction direction being a vertical direction, a vertical intra prediction mode is stored as the intra prediction mode of the current block,
• wherein the first sample is a sample in the current block adjacent to the neighboring sample, and the second sample is a sample in the current block adjacent to the first sample in the prediction direction,
• wherein the intra prediction mode stored as the intra prediction mode of the current block is used for prediction for a block coded after the current block, and
• wherein the block coded after the current block is a block within a current Coding Tree Unit (CTU) or a neighboring CTU in a current picture or a reference picture.