Intra prediction mode encoding/decoding method and apparatus for same
Disclosed herein is an intra prediction method including: deriving neighbor prediction mode information from a left neighbor prediction mode and an upper neighbor prediction mode; deriving an intra prediction mode for a decoding target unit by using the derived neighbor prediction mode information; and performing intra prediction on the decoding target unit based on the intra prediction mode. According to exemplary embodiments of the present invention, image encoding/decoding efficiency can be improved.
1. A video decoding apparatus comprising:
an inverse-transformation module to perform inverse-transformation on transform coefficients to generate a residual block;
wherein the transform coefficients are derived from quantized transform coefficients related to a target decoding unit; wherein the quantized transform coefficients are derived from decoding an input bitstream;
a prediction module to
receive and decode a most probable mode (MPM) flag and an MPM index for the target decoding unit;
derive neighbor prediction mode information from a left neighbor prediction mode and an upper neighbor prediction mode;
determine MPM candidates for the target decoding unit using the neighbor prediction mode information;
generate an MPM list using the determined MPM candidates;
derive an intra prediction mode of the target decoding unit using the decoded MPM index and the generated MPM list; and
perform intra prediction on the target decoding unit based on the derived intra prediction mode, and
an adder to add the residual block and a prediction block generated by the intra prediction to generate a reconstructed block,
wherein the left neighbor prediction mode is an intra prediction mode of a left neighbor unit adjacent to a left side of the target decoding unit and the upper neighbor prediction mode is an intra prediction mode of an upper neighbor unit adjacent to an upper side of the target decoding unit, and the MPM index is an index indicating the same candidate as the intra prediction mode of the target decoding unit, among the MPM candidates included in the MPM list,
wherein the neighbor prediction mode information includes a mode number of the left neighbor prediction mode and a mode number of the upper neighbor prediction mode,
wherein the prediction module determines the left neighbor prediction mode and the upper neighbor prediction mode as the MPM candidates, and the MPM list comprises three MPM candidates, and
wherein the prediction module determines a predetermined intra prediction mode as an additional MPM candidate when the left neighbor prediction mode is the same as the upper neighbor prediction mode.
2. The video decoding apparatus of claim 1 , wherein the predetermined intra prediction mode is a DC mode or planar mode.
3. The video decoding apparatus of claim 2 , wherein the predetermined intra prediction mode is a DC mode when the left neighbor prediction mode and the upper neighbor prediction mode are a planar mode, and the predetermined intra prediction mode is a planar mode when the left neighbor prediction mode and the upper neighbor prediction mode are a DC mode.
4. A video encoding apparatus comprising:
a prediction module to
determine an intra prediction mode of a target encoding unit;
perform intra prediction on the target encoding unit based on the determined intra prediction mode;
derive neighbor prediction mode information from a left neighbor prediction mode and an upper neighbor prediction mode;
determine MPM candidates for the target encoding unit using the neighbor prediction mode information;
generate an MPM list using the determined MPM candidates;
derive an MPM index using the intra prediction mode of the target encoding unit and the generated MPM list; and
encode a most probable mode (MPM) flag and the MPM index for the target encoding unit;
a subtractor to generate a residual block using the prediction block generated by the intra prediction and the target encoding unit;
a transformation module to perform transformation on coefficients related to the residual block to derive transform coefficients;
wherein quantized transform coefficients related to the target encoding unit as derived from the transform coefficients, along with the MPM flag and the MPM index, are encoded in a bitstream;
wherein the left neighbor prediction mode is an intra prediction mode of a left neighbor unit adjacent to a left side of the target encoding unit and the upper neighbor prediction mode is an intra prediction mode of an upper neighbor unit adjacent to an upper side of the target encoding unit, and the MPM index is an index indicating the same candidate as the intra prediction mode of the target encoding unit, among the MPM candidates included in the MPM list,
wherein the neighbor prediction mode information includes a mode number of the left neighbor prediction mode and a mode number of the upper neighbor prediction mode,
wherein the prediction module determines the left neighbor prediction mode and the upper neighbor prediction mode as the MPM candidates, and the MPM list comprises three MPM candidates, and
wherein the prediction module determines a predetermined intra prediction mode as an additional MPM candidate when the left neighbor prediction mode is the same as the upper neighbor prediction mode.
5. The video encoding apparatus of claim 4 , wherein the predetermined intra prediction mode is a DC mode or planar mode.
6. The video encoding apparatus of claim 5 , wherein the predetermined intra prediction mode is a DC mode when the left neighbor prediction mode and the upper neighbor prediction mode are a planar mode, and the predetermined intra prediction mode is a planar mode when the left neighbor prediction mode and the upper neighbor prediction mode are a DC mode.
7. A non-transitory computer-readable medium storing a bitstream that is received and used by a video decoding apparatus to reconstruct a video, the bitstream comprises information on quantization transform coefficients related to a target decoding unit, a most probable mode (MPM) flag and an MPM index for the target decoding unit,
wherein the quantization transform coefficients are used to derive transform coefficients,
the transform coefficients are used to generate a residual block by being inverse-transformed,
the MPM flag and the MPM index are used to derive an intra prediction mode of the target decoding using an MPM list,
wherein the MPM list is generated using MPM candidates for the target decoding unit,
the MPM candidates are determined using neighbor prediction mode information which is derived from a left neighbor prediction mode and an upper neighbor prediction mode,
the derived intra prediction mode is used to perform intra prediction on the target decoding unit to generate a prediction block,
the residual block and the prediction block are used to generate a reconstructed block,
wherein the left neighbor prediction mode is an intra prediction mode of a left neighbor unit adjacent to a left side of the target decoding unit and the upper neighbor prediction mode is an intra prediction mode of an upper neighbor unit adjacent to an upper side of the target decoding unit, and the MPM index is an index indicating the same candidate as the intra prediction mode of the target decoding unit, among the MPM candidates included in the MPM list,
wherein the neighbor prediction mode information includes a mode number of the left neighbor prediction mode and a mode number of the upper neighbor prediction mode,
wherein the prediction module determines the left neighbor prediction mode and the upper neighbor prediction mode as the MPM candidates, and the MPM list comprises three MPM candidates, and
wherein the prediction module determines a predetermined intra prediction mode as an additional MPM candidate when the left neighbor prediction mode is the same as the upper neighbor prediction mode.