Intra prediction mode derivation-based intra prediction method and device

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

• determining whether at least one of Template-based Intra Mode Derivation (TIMD) mode or Decoder Side Intra Mode Derivation (DIMD) mode is applied to a current block;
• generating a prediction sample of the current block based on at least one of the TIMD mode or the DIMD mode;
• generating prediction-related information based on the prediction sample of the current block;
• and
• encoding image information including the prediction-related information,
• wherein the TIMD mode is derived based on a template of the current block,
• wherein the DIMD mode is derived based on a gradient of neighboring reference samples of the current block,
• wherein the image decoding method further comprises constructing a most probable mode (MPM) list including a candidate intra prediction mode,
• wherein an intra prediction mode is derived based on the MPM list,
• wherein the MPM list includes a primary MPM list and a secondary MPM list, and
• wherein, based on the TIMD mode being applied to the current block, the candidate intra prediction mode derived based on the TIMD mode is inserted into the MPM list.

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

• obtaining a bitstream for the image, wherein the bitstream is generated based on determining whether at least one of Template-based Intra Mode Derivation (TIMD) mode or Decoder Side Intra Mode Derivation (DIMD) mode is applied to a current block, generating a prediction sample of the current block based on at least one of the TIMD mode or the DIMD mode, generating prediction-related information based on the prediction sample of the current block, and encoding image information including the prediction-related information;
• and
• transmitting the data including the bitstream,
• wherein the TIMD mode is derived based on a template of the current block,
• wherein the DIMD mode is derived based on a gradient of neighboring reference samples of the current block,
• wherein the image decoding method further comprises constructing a most probable mode MPM) list including a candidate intra prediction mode,
• wherein an intra prediction mode is derived based on the MPM list,
• wherein the MPM list includes a primary MPM list and a secondary MPM list, and
• wherein, based on the TIMD mode being applied to the current block, the candidate intra prediction mode derived based on the TIMD mode is inserted into the MPM list.