Method for coding image/video on basis of intra prediction and device therefor
An image decoding method according to the present disclosure comprises the steps of: obtaining intra prediction type related information for a current block from a bit stream; deriving the intra prediction type of the current block based on the intra prediction type-related information; obtaining intra prediction mode-related information for the current block from the bitstream; configuring a most probable mode (MPM) list including candidate intra prediction modes for the current block based on neighboring blocks of the current block; deriving the intra prediction mode of the current block based on the MPM list and the intra prediction mode-related information; and generating a predicted block of the current block based on the intra prediction type and the intra prediction mode, wherein when the intra prediction type indicates the particular intra prediction type, the MPM index is parsed from the bit stream without parsing of an MPM flag.
1. A decoding apparatus for image decoding, the decoding apparatus comprising:
a memory storing instructions; and
at least one processor connected to the memory, the at least one processor executing the instructions to perform operations comprising:
acquiring information about an intra prediction type of a current block from a bitstream;
deriving the intra prediction type of the current block based on the information about the intra prediction type;
acquiring information about an intra prediction mode of the current block from the bitstream;
configuring a most probable mode (MPM) list comprising candidate intra prediction modes of the current block based on neighboring blocks of the current block;
deriving the intra prediction mode of the current block based on the MPM list and the information about the intra prediction mode; and
generating a predicted block of the current block by performing intra prediction based on the intra prediction type and the intra prediction mode,
wherein the intra prediction type includes a first intra prediction type and a second intra prediction type,
wherein, for the first intra prediction type, the intra prediction is performed based on neighboring reference samples in a specific sample line which is not adjacent to a top boundary and a left boundary of the current block,
wherein, for the second intra prediction type, the intra prediction is performed based on neighboring reference samples in a specific sample line which is adjacent to the top boundary and the left boundary of the current block,
wherein, based on the intra prediction type representing the first intra prediction type, the information about the intra prediction mode comprises: an MPM index,
wherein, based on the intra prediction type representing the first intra prediction type, the MPM index is parsed without parsing an MPM flag from the bitstream,
wherein, based on the intra prediction type representing the second intra prediction type, the MPM flag is parsed from the bitstream,
wherein, based on the intra prediction type representing the second intra prediction type, the information about the intra prediction mode comprises the MPM index based on the MPM flag, and
wherein an intra prediction based on the first intra prediction type is performed on the current block based on the intra prediction mode of the current block not being a planar mode.
2. The decoding apparatus of claim 1 , wherein the first intra prediction type comprises: a multi-reference line (MRL) intra prediction type,
wherein the information about the intra prediction type comprises: intra_luma_ref_idx, and wherein based on a value of the intra_luma_ref_idx being larger than 0, the MRL intra prediction type is derived as the intra prediction type of the current block.
3. An encoding apparatus for image encoding, the encoding apparatus configured to:
a memory storing instructions; and
at least one processor connected to the memory, the at least one processor executing the instructions to perform operations comprising:
determining an intra prediction type of a current block;
generating information about the intra prediction type of the current block;
configuring a most probable mode (MPM) list comprising candidate intra prediction modes of the current block based on neighboring blocks of the current block;
deriving an intra prediction mode of the current block based on the MPM list;
generating information about the intra prediction mode of the current block; and
outputting a bitstream by encoding image information comprising the information about the intra prediction type and the information about the intra prediction mode,
wherein the information about the intra prediction mode is generated based on the intra prediction type,
wherein the intra prediction type includes a first intra prediction type and a second intra prediction type,
wherein, for the first intra prediction type, the intra prediction is performed based on neighboring reference samples in a specific sample line which is not adjacent to a top boundary and a left boundary of the current block,
wherein, for the second intra prediction type, the intra prediction is performed based on neighboring reference samples in a specific sample line which is adjacent to the top boundary and the left boundary of the current block,
wherein, based on the intra prediction type representing the first intra prediction type, the information about the intra prediction mode comprises: an MPM index,
wherein, based on the intra prediction type representing the first intra prediction type, the MPM index is configured to be parsed without parsing an MPM flag from the bitstream and the intra prediction mode of the current block is limited to one of candidate intra prediction modes within the MPM list,
wherein, based on the intra prediction type representing the second intra prediction type, the MPM flag is configured to be parsed from the bitstream,
wherein, based on the intra prediction type representing the second intra prediction type, the information about the intra prediction mode comprises the MPM index based on the MPM flag, and
wherein an intra prediction based on the first intra prediction type is performed on the current block based on the intra prediction mode of the current block not being a planar mode.
4. An apparatus configured to transmit data for an image, the apparatus comprising:
at least one processor configured to obtain a bitstream, wherein the bitstream is generated based on determining an intra prediction type of a current block, generating information about the intra prediction type of the current block, configuring a most probable mode (MPM) list comprising candidate intra prediction modes of the current block based on neighboring blocks of the current block, deriving an intra prediction mode of the current block based on the MPM list, generating information about the intra prediction mode of the current block, and outputting the bitstream by encoding image information comprising the information about the intra prediction type and the information about the intra prediction mode; and
a transmitter configured to transmit the data comprising the bitstream,
wherein the information about the intra prediction mode is generated based on the intra prediction type,
wherein the intra prediction type includes a first intra prediction type and a second intra prediction type,
wherein, for the first intra prediction type, the intra prediction is performed based on neighboring reference samples in a specific sample line which is not adjacent to a top boundary and a left boundary of the current block,
wherein, for the second intra prediction type, the intra prediction is performed based on neighboring reference samples in a specific sample line which is adjacent to the top boundary and the left boundary of the current block,
wherein based on the intra prediction type representing the first intra prediction type, the information about the intra prediction mode comprises: an MPM index,
wherein, based on the intra prediction type representing the first intra prediction type, the MPM index is configured to be parsed without parsing an MPM flag from the bitstream and the intra prediction mode of the current block is limited to one of candidate intra prediction modes within the MPM list,
wherein, based on the intra prediction type representing the second intra prediction type, the MPM flag is configured to be parsed from the bitstream,
wherein, based on the intra prediction type representing the second intra prediction type, the information about the intra prediction mode comprises the MPM index based on the MPM flag, and
wherein an intra prediction based on the first intra prediction type is performed on the current block based on the intra prediction mode of the current block not being a planar mode.