Intra prediction mode mapping method and device using the method
View Patent ↗The present invention relates to an intra prediction mode mapping method and a device using the method. The intra prediction mode includes: decoding flag information providing information regarding whether an intra prediction mode of a plurality of candidate intra prediction modes for the current block is the same as the intra prediction mode for the current block, and decoding a syntax component including information regarding the intra prediction mode for the current block in order to induce the intra prediction mode for the current block if the intra prediction mode from among the plurality of candidate intra prediction modes for the current block is not the same as the intra prediction mode for the current block. Thus, it is possible to increase the efficiency with which are images are decoded.
1. An intra-prediction method comprising:
decoding flag information indicating whether one of a plurality of candidate intra-prediction modes with respect to a current block and an intra-prediction mode of the current block are identical; and
when one of a plurality of candidate intra-prediction modes with respect to a current block and an intra-prediction mode of the current block are not identical, decoding a syntax element comprising information regarding the intra-prediction mode of the current block to derive the intra-prediction mode of the current block,
wherein, the decoding of a syntax element comprising information regarding the intra-prediction mode of the current block to derive the intra-prediction mode of the current block is performed based on a table comprising intra-prediction mode information, the table is a table mapping intra-prediction modes and index information of the intra-prediction modes, and, in the table, when an intra-prediction mode is a planar mode, the intra-prediction mode is mapped to an index 0, when an intra-prediction mode is a DC mode, the intra-prediction mode is mapped to an index 1, and when intra-prediction modes are directional intra-prediction modes, the intra-prediction modes are mapped to indices 2 to 34 according to directivity of the intra-prediction modes,
wherein the plurality of candidate intra-prediction modes with respect to the current block are three different intra-prediction modes derived based on at least one intra-prediction mode derived based on neighbor blocks of the current block and an additional intra-prediction mode.
2. The method of claim 1 , wherein the syntax element comprising information regarding an intra-prediction mode of a current block is a value coded using fixed 5 bits, and the 5-bit information indicates one of a remaining intra-prediction mode information, excluding a plurality of candidate intra-prediction modes with respect to the current block.
3. The method of claim 1 , wherein when the flag information is 1, the flag information indicates that one of the candidate intra-prediction modes of the current block and the intra-prediction mode of the current block are identical, and when the flag information is 0, the flag information indicates that the plurality of candidate intra-prediction modes of the current block and the intra-prediction mode of the current block are not identical.
4. The method of claim 1 , wherein the decoding of a syntax element comprising information regarding the intra-prediction mode of the current block to derive the intra-prediction mode of the current block comprises:
deriving the remaining 32 intra-prediction mode information, excluding 3 intra-prediction modes as a plurality of candidate intra-prediction modes with respect to the current block, in the table;
mapping syntax element comprising information regarding the intra-prediction mode of the current block to the remaining 32 intra-prediction mode information; and
setting one intra-prediction mode, among the remaining 32 intra-prediction mode information, mapped to the syntax element, as an intra-prediction mode of the current block.
5. A video decoding apparatus comprising:
an entropy-decoding module configured to decode flag information indicating whether one of a plurality of candidate intra-prediction modes with respect to a current block and an intra-prediction mode of the current block are identical, and configured to decode a syntax element comprising information regarding the intra-prediction mode of the current block to derive the intra-prediction mode of the current block, when one of a plurality of candidate infra-prediction modes with respect to a current block and an intra-prediction mode of the current block are not identical; and
a prediction module configured to derive the intra-prediction mode of the current block based on the decoded syntax element, when one of a plurality of candidate intra-prediction modes with respect to a current block and an intra-prediction mode of the current block are not identical,
wherein the table is a table mapping intra-prediction modes and index information of the intra-prediction modes, and, in the table, when an intra-prediction mode is a planar mode, the intra-prediction mode is mapped to an index 0, when an intra-prediction mode is a DC mode, the intra-prediction mode is mapped to an index 1, and when intra-prediction modes are directional intra-prediction modes, the intra-prediction modes are mapped to indices 2 to 34according to directivity of the intra-prediction modes,
the plurality of candidate intra-prediction modes with respect to the current block are three different intra-prediction modes derived based on at least one intra-prediction mode derived based on neighbor blocks of the current block and a additional intra-prediction mode.
6. The video decoding apparatus of claim 5 , wherein the syntax element is a value coded using fixed 5 bits, and the 5-bit information indicates one of a remaining intra-prediction mode information, excluding a plurality of candidate intra-prediction modes with respect to the current block.
7. The video decoding apparatus of claim 5 , when the flag information is 1, the flag information indicates that one of the candidate intra-prediction modes of the current block and the intra-prediction mode of the current block are identical, and when the flag information is 0, the flag information indicates that the plurality of candidate intra-prediction modes of the current block and the intra-prediction mode of the current block are not identical.
8. The video decoding apparatus of claim 5 , the prediction module derives the remaining 32 intra-prediction mode information, excluding 3 intra-prediction modes as a plurality of candidate intra-prediction modes with respect to the current block, in the table, maps syntax element comprising information regarding the intra-prediction mode of the current block to the remaining 32 intra-prediction mode information, and sets one intra-prediction mode, among the remaining 32 intra-prediction mode information, mapped to the syntax element, as an infra-prediction mode of the current.