Method for coding intra-prediction mode, and device for same
A picture decoding method which is performed by a decoding apparatus according to an example of the present disclosure includes constructing a Most Probable Modes (MPM) list including intra prediction mode candidates for a current block based on neighboring blocks of the current block, decoding remaining mode information indicating one of remaining intra prediction modes other than the intra prediction mode candidates included in the MPM list from a bitstream, determining an intra prediction mode of the current block based on the decoded remaining mode information, generating prediction samples for the current block based on the determined intra prediction mode, and generating reconstructed samples for the current block based on the prediction samples for the current block, wherein the remaining mode information is decoded based on a truncated binary code.
1. An image decoding method performed by a decoding apparatus, the method comprising:
receiving prediction related information and residual information from a bitstream;
determining that an intra prediction is applied for a current block based on the prediction related information;
constructing a Most Probable Mode (MPM) list including intra prediction mode candidates for the current block based on neighboring blocks of the current block;
decoding remaining mode information indicating one of remaining intra prediction modes not included in the MPM list from the bitstream;
deriving an intra prediction mode of the current block based on the remaining mode information;
generating prediction samples for the current block based on the intra prediction mode;
deriving transform coefficients based on the residual information;
generating residual samples for the current block based on the transform coefficients; and
generating reconstructed samples for the current block based on the prediction samples for the current block and the residual samples for the current block,
wherein the neighboring blocks of the current block include a left neighboring block and an upper neighboring block,
wherein the remaining mode information is decoded based on a truncated binary code,
wherein a number of bits of the truncated binary code for first intra prediction modes of the remaining intra prediction modes is k, and a number of bits of the truncated binary code for second intra prediction modes excepting the first intra prediction modes among the remaining intra prediction modes is k+1,
wherein a number of the first intra prediction modes is L, and
wherein a following equation is applied between the k and u,
k =floor(log 2 u )
wherein the u represents a total number of the remaining intra prediction modes.
2. An image encoding method performed by an encoding apparatus, the method comprising:
determining that an intra prediction is applied for a current block;
constructing a Most Probable Mode (MPM) list including intra prediction mode candidates for the current block based on neighboring blocks of the current block;
generating remaining mode information indicating, as an intra prediction mode of the current block, one of remaining intra prediction modes not included in the MPM list;
generating prediction samples for the current block based on the intra prediction mode of the current block;
deriving residual samples for the current block based on the prediction samples for the current block;
deriving transform coefficients based on the residual samples;
generating residual information based on the transform coefficients; and
encoding image information including the residual information and the remaining mode information,
wherein the neighboring blocks of the current block include a left neighboring block and an upper neighboring block,
wherein the remaining mode information included in the image information is encoded based on a truncated binary code,
wherein a number of bits of the truncated binary code for first intra prediction modes of the remaining intra prediction modes is k, and a number of bits of the truncated binary code for second intra prediction modes excepting the first intra prediction modes among the remaining intra prediction modes is k+1,
wherein a number of the first intra prediction modes is L, and
wherein a following equation is applied between the k and u,
k =floor(log 2 u )
wherein the u represents a total number of the remaining intra prediction modes.
3. A transmission method of data for an image, the method comprising:
obtaining a bitstream for the image, wherein the bitstream is generated based on determining that an intra prediction is applied for a current block, constructing a Most Probable Mode (MPM) list including intra prediction mode candidates for the current block based on neighboring blocks of the current block, generating remaining mode information indicating, as an intra prediction mode of the current block, one of remaining intra prediction modes not included in the MPM list, generating prediction samples for the current block based on the intra prediction mode of the current block, deriving residual samples for the current block based on the prediction samples for the current block, deriving transform coefficients based on the residual samples, generating residual information based on the transform coefficients, and encoding image information including the residual information and the remaining mode information; and
transmitting the data comprising the bitstream,
wherein the neighboring blocks of the current block include a left neighboring block and an upper neighboring block,
wherein the remaining mode information included in the image information is encoded based on a truncated binary code,
wherein a number of bits of the truncated binary code for first intra prediction modes of the remaining intra prediction modes is k, and a number of bits of the truncated binary code for second intra prediction modes excepting the first intra prediction modes among the remaining intra prediction modes is k+1,
wherein a number of the first intra prediction modes is L, and
wherein a following equation is applied between the k and u,
k =floor(log 2 u )
wherein the u represents a total number of the remaining intra prediction modes.