Method for coding intra-prediction mode, and device for same

1. A decoding apparatus for image decoding, the decoding apparatus comprising:

a memory; and

at least one processor connected to the memory, the at least one processor configured to:

receive prediction related information and residual information from a bitstream;

determine that an intra prediction is applied for a current block based on the prediction related information;

construct a Most Probable Mode (MPM) list including intra prediction mode candidates for the current block based on neighboring blocks of the current block;

decode remaining mode information indicating one of remaining intra prediction modes not included in the MPM list from the bitstream;

derive an intra prediction mode of the current block based on the remaining mode information;

generate prediction samples for the current block based on the intra prediction mode;

derive transform coefficients based on the residual information;

generate residual samples for the current block based on the transform coefficients; and

generate 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 encoding apparatus for image encoding, the encoding apparatus comprising:

a memory; and

at least one processor connected to the memory, the at least one processor configured to:

determine that an intra prediction is applied for a current block;

construct a Most Probable Mode (MPM) list including intra prediction mode candidates for the current block based on neighboring blocks of the current block;

generate 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;

generate prediction samples for the current block based on the intra prediction mode of the current block;

derive residual samples for the current block based on the prediction samples for the current block;

derive transform coefficients based on the residual samples;

generate residual information based on the transform coefficients; and

encode 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. An apparatus for transmitting data for an image, the apparatus comprising:

at least one processor configured to obtain 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

a transmitter configured to transmit 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.