Image encoding/decoding method and device using intra prediction
View Patent ↗The image encoding/decoding method and device according to the present invention may determine an intra prediction mode of a current block and perform intra prediction on the current block on the basis of the intra prediction mode, wherein the intra prediction mode of the current block is determined for each of a luminance block and a color difference block.
1. A method of decoding an image, comprising:
determining an intra prediction mode of a current block; and
performing intra prediction on the current block based on the intra prediction mode, wherein the intra prediction mode of the current block is determined for each of a luma block and a chroma block, respectively,
wherein the intra prediction mode of the luma block is derived based on an MPM (Most Probable Mode) list and an MPM index, and
wherein the current block is divided into a plurality of sub-blocks based on at least one of a size or a shape of the current block, and a plurality of divided lower sub-blocks belonging to a higher coding block share the MPM list,
when the size of the current block is smaller than a pre-determined threshold size, the current block is divided into two vertically or horizontally, and
when the size of the current block is greater than or equal to the pre-determined threshold size, the current block is divided into four vertically or horizontally.
2. The method of claim 1 , wherein performing the intra prediction comprises:
specifying a luma region for inter-components reference of the chroma block;
performing down-sampling for the luma region;
deriving a parameter for the inter-components reference of the chroma block; and
predicting the chroma block based on the down-sampled luma region and the parameter.
3. The method of claim 1 , wherein:
the MPM list includes an intra prediction mode of a neighboring block (ModeA), ModeA+n, and ModeA−n.
4. A method of encoding an image, comprising:
determining an intra prediction mode of a current block;
performing intra prediction on the current block based on the intra prediction mode, wherein the intra prediction mode of the current block is determined for each of a luma block and a chroma block, respectively; and
encoding an MPM index into a bitstream,
wherein the intra prediction mode of the luma block is derived based on an MPM (Most Probable Mode) list and an MPM index, and
wherein the current block is divided into a plurality of sub-blocks based on at least one of a size or a shape of the current block, and a plurality of divided lower sub-blocks belonging to a higher coding block share the MPM list,
when the size of the current block is smaller than a pre-determined threshold size, the current block is divided into two vertically or horizontally, and
when the size of the current block is greater than or equal to the pre-determined threshold size, the current block is divided into four vertically or horizontally.
5. The method of claim 4 , wherein performing the intra prediction comprises:
specifying a luma region for inter-components reference of the chroma block;
performing down-sampling for the luma region;
deriving a parameter for the inter-components reference of the chroma block; and
predicting the chroma block based on the down-sampled luma region and the parameter.
6. The method of claim 4 , wherein:
the MPM list includes an intra prediction mode of a neighboring block (ModeA), ModeA+n, and ModeA−n.
7. A decoder, comprising a memory and a processor, wherein
the memory is configured to store computer programs capable of running in the processor; and
the processor is configured to run the computer programs to execute:
determining an intra prediction mode of a current block; and
performing intra prediction on the current block based on the intra prediction mode, wherein the intra prediction mode of the current block is determined for each of a luma block and a chroma block, respectively,
wherein the intra prediction mode of the luma block is derived based on an MPM (Most Probable Mode) list and an MPM index, and
wherein the current block is divided into a plurality of sub-blocks based on at least one of a size or a shape of the current block, and a plurality of divided lower sub-blocks belonging to a higher coding block share the MPM list,
when the size of the current block is smaller than a pre-determined threshold size, the current block is divided into two vertically or horizontally, and
when the size of the current block is greater than or equal to the pre-determined threshold size, the current block is divided into four vertically or horizontally.
8. The decoder of claim 7 , wherein the processor is further configured to run the computer programs to execute:
specifying a luma region for inter-components reference of the chroma block;
performing down-sampling for the luma region;
deriving a parameter for the inter-components reference of the chroma block; and
predicting the chroma block based on the down-sampled luma region and the parameter.
9. The decoder of claim 7 , wherein:
the MPM list includes an intra prediction mode of a neighboring block (ModeA), ModeA+n, and ModeA−n.
10. An encoder, comprising a memory and a processor, wherein
the memory is configured to store computer programs capable of running in the processor; and
the processor is configured to run the computer programs to execute:
determining an intra prediction mode of a current block;
performing intra prediction on the current block based on the intra prediction mode, wherein the intra prediction mode of the current block is determined for each of a luma block and a chroma block, respectively; and
encoding an MPM index into a bitstream,
wherein the intra prediction mode of the luma block is derived based on an MPM (Most Probable Mode) list and an MPM index, and
wherein the current block is divided into a plurality of sub-blocks based on at least one of a size or a shape of the current block, and a plurality of divided lower sub-blocks belonging to a higher coding block share the MPM list,
when the size of the current block is smaller than a pre-determined threshold size, the current block is divided into two vertically or horizontally, and
when the size of the current block is greater than or equal to the pre-determined threshold size, the current block is divided into four vertically or horizontally.
11. The encoder of claim 10 , wherein the processor is further configured to run the computer programs to execute:
specifying a luma region for inter-components reference of the chroma block;
performing down-sampling for the luma region;
deriving a parameter for the inter-components reference of the chroma block; and
predicting the chroma block based on the down-sampled luma region and the parameter.
12. The encoder of claim 10 , wherein:
the MPM list includes an intra prediction mode of a neighboring block (ModeA), ModeA+n, and ModeA−n.