Method and device for encoding intra prediction mode for image prediction unit, and method and device for decoding intra prediction mode for image prediction unit
Methods and apparatuses for encoding and decoding an intra prediction mode of a prediction unit of a chrominance component based on an intra prediction mode of a prediction unit of a luminance component are provided. When an intra prediction mode of a prediction unit of a luminance component is the same as an intra prediction mode in an intra prediction mode candidate group of a prediction unit of a chrominance component, reconstructing the intra prediction mode candidate group of the prediction unit of the chrominance component by excluding or replacing an intra prediction mode of the prediction unit of the chrominance component which is same as an intra prediction mode of the prediction unit of the luminance component from the intra prediction mode candidate group, and encoding the intra prediction mode of the prediction unit of the chrominance component by using the reconstructed intra prediction mode candidate group.
1. A method of decoding an image, the method comprising:
splitting an image into a plurality of maximum coding units;
hierarchically splitting a maximum coding unit from among the plurality of maximum coding units into at least one coding unit including a current coding unit based on split information;
obtaining intra prediction mode information regarding a prediction unit of a first image component of the image from a bitstream;
when an intra prediction mode indicated by the intra prediction mode information regarding the prediction unit of the first image component is one of a planar mode, a DC mode, a horizontal mode and a vertical mode, obtaining an intra prediction mode candidate group regarding a second image component, wherein the intra prediction mode candidate group regarding the second image component includes a diagonal mode;
obtaining intra prediction mode information regarding a prediction unit of the second image component;
determining an intra prediction mode regarding the prediction unit of the second image component from among a plurality of intra prediction modes which are included in the intra mode prediction candidate group regarding the second image component based on the obtained intra prediction mode information regarding the prediction unit of the second image component;
performing intra prediction on the prediction unit of the first image component according to the intra prediction mode indicated by the intra prediction mode information regarding the prediction unit of the first image component; and
performing intra prediction on the prediction unit of the second image component according to the determined intra prediction mode,
wherein the performing intra prediction on the prediction unit of the first image component comprises, when the intra prediction mode indicated by the intra prediction mode information regarding the prediction unit of the first image component is the planar mode, obtaining a prediction value of a current pixel included in a block in the prediction unit of the first image component using four neighboring pixels of the block in the prediction unit of the first image component,
wherein the current coding unit is a coding unit which is not split according to the split information,
wherein the prediction unit of the first image component is determined by splitting the current coding unit based on partition type information, and
wherein the partition type information indicates whether a partition type of symmetrically splitting the current coding unit along at least one of a height and a width of the current coding unit.
2. The method of claim 1 , wherein the intra prediction mode information regarding the prediction unit of the second image component comprises an index which indicates one of a plurality of intra prediction modes included in the intra prediction modes included in the intra prediction mode candidate group regarding the second image component.
3. A method of encoding an image, the method comprising:
determining a plurality of maximum coding units by splitting an image into the plurality of the maximum coding units;
determining at least one coding unit including a current coding unit by hierarchically splitting a maximum coding unit from among the plurality of maximum coding units into the at least one coding unit, wherein the current coding unit is a coding unit of a current depth which is not split into coding units of a lower depth;
determining one or more prediction unit including a prediction unit of a first image component by splitting the current coding unit;
determining an intra prediction mode regarding the prediction unit of the first image component by performing intra prediction on the prediction unit of the first image component;
determining an intra prediction mode regarding an intra prediction mode regarding a prediction unit of a second image component by performing intra prediction on the prediction unit of the second image component;
generating intra prediction mode information regarding the prediction unit of the first image component of the image;
when an intra prediction mode indicated by the intra prediction mode information regarding the prediction unit of the first image component is one of a planar mode, a DC mode, a horizontal mode and a vertical mode, generating an intra prediction mode candidate group regarding the second image component, wherein the intra prediction mode candidate group regarding the second image component includes a diagonal mode;
generating intra prediction mode information regarding a prediction unit of the second image component based on a plurality of intra prediction modes included in the intra mode prediction candidate group regarding the second image component;
generating split information which indicates whether a split of coding units in the maximum coding unit,
generating partition type information indicates whether a partition type of symmetrically splitting the current coding unit along at least one of a height and a width of the current coding unit; and
generating a bitstream including the intra prediction mode information regarding the prediction unit of the first image component of the image, the intra prediction mode information regarding the prediction unit of the second image component, the split information and partition type information,
wherein the determining of the intra prediction mode regarding the prediction unit of the first image component comprises when a prediction value of a current pixel included in a block in the prediction unit of the first image component using four neighboring pixels of the block in the prediction unit of the first image component in performing the intra prediction on the prediction unit of the first image component, determining the intra prediction mode regarding the prediction unit of the first image component as a planar mode.
4. A non-transitory computer-readable storage medium storing a bitstream comprising:
intra prediction mode information regarding a prediction unit of a first image component of an image;
intra prediction mode information regarding a prediction unit of a second image component of the image;
split information which indicates whether a split of coding units in a maximum coding unit; and
partition type information indicates whether a partition type of symmetrically splitting a coding unit of a first depth along at least one of a height and a width of the coding unit of the first depth when the coding unit of the first depth is not split into coding units of a second depth which is lower than the first depth,
wherein a plurality of maximum coding units are determined by splitting an image into a plurality of maximum coding units,
at least one coding unit including a current coding unit is determined by hierarchically splitting a maximum coding unit from among the plurality of maximum coding units into the at least one coding unit, wherein the current coding unit is a coding unit of a current depth which is not split into coding units of a lower depth,
wherein one or more prediction unit including the prediction unit of the first image component are determined by splitting the current coding unit,
when an intra prediction mode indicated by the intra prediction mode information regarding the prediction unit of the first image component is one of a planar mode, a DC mode, a horizontal mode and a vertical mode, an intra prediction mode candidate group regarding the second image component is generated, wherein the intra prediction mode candidate group regarding the second image component includes a diagonal mode,
the intra prediction mode information regarding the prediction unit of the second image component is generated based on a plurality of intra prediction modes included in the intra mode prediction candidate group regarding the second image component,
the partition type information is generated to indicate whether a partition type of symmetrically splitting the current coding unit along at least one of a height and a width of the current coding unit, and
wherein when a prediction value of a current pixel included in a block in the prediction unit of the first image component using four neighboring pixels of the block in the prediction unit of the first image component in performing the intra prediction on the prediction unit of the first image component, the intra prediction mode regarding the prediction unit of the first image component is determined as a planar mode.