Intra prediction-based video coding method and device using MPM list

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

• deriving a first intra prediction mode of a first neighboring block adjacent to a left of a current block and a second intra prediction mode of a second neighboring block adjacent to an upper of the current block;
• constructing a most probable mode (MPM) list based on the first intra prediction mode and the second intra prediction mode;
• generating intra prediction mode information based on the MPM list;
• encoding image information including the intra prediction mode information,
• wherein the MPM list includes candidate intra prediction modes for the current block,
• wherein based on a case where the first intra prediction mode of the first neighboring block and the second intra prediction mode of the second neighboring block are the same and both the first intra prediction mode and the second intra prediction mode are the DC mode, the candidate intra prediction modes in the MPM list include a DC mode, and include an intra prediction mode 50, an intra prediction mode 18, an intra prediction mode 46, and an intra prediction mode 54, and
• wherein, in the MPM list, an index value for the DC mode is smaller than an index value for the intra prediction mode 50, the index value for the intra prediction mode 50 is smaller than an index value for the intra prediction mode 18, the index value for the prediction mode 18 is smaller than an index value for the intra prediction mode 46, and the index value for the intra prediction mode 46 is smaller than an index value for the intra prediction mode 54.

A non-transitory computer readable digital storage medium storing a bitstream generated by a method, the method comprising:

• deriving a first intra prediction mode of a first neighboring block adjacent to a left of a current block and a second intra prediction mode of a second neighboring block adjacent to an upper of the current block;
• constructing a most probable mode (MPM) list based on the first intra prediction mode and the second intra prediction mode;
• generating intra prediction mode information based on the MPM list;
• generating the bitstream by encoding image information including the intra intra prediction mode information,
• wherein the MPM list includes candidate intra prediction modes for the current block, wherein based on a case where the first intra prediction mode of the first neighboring block and the second intra prediction mode of the second neighboring block are the same and both the first intra prediction mode and the second intra prediction mode are the DC mode, the candidate intra prediction modes in the MPM list include a DC mode, and include an intra prediction mode 50, an intra prediction mode 18, an intra prediction mode 46, and an intra prediction mode 54, and
• wherein, in the MPM list, an index value for the DC mode is smaller than an index value for the intra prediction mode 50, the index value for the intra prediction mode 50 is smaller than an index value for the intra prediction mode 18, the index value for the prediction mode 18 is smaller than an index value for the intra prediction mode 46, and the index value for the intra prediction mode 46 is smaller than an index value for the intra prediction mode 54.