Image encoding/decoding method and device for utilizing simplified MPM list generation method, and method for transmitting bitstream
An image encoding/decoding method and apparatus are provided. An image decoding method performed by an image decoding apparatus may include identifying a prediction mode of a current block, determining a candidate intra prediction mode for the current block, based on a prediction mode of a neighboring block located around the current block, based on the intra prediction mode of the current block being an intra prediction mode, generating a candidate intra prediction mode list of the current block based on the candidate intra prediction mode, and determine an intra prediction mode of the current block based on the candidate intra prediction mode list. In this case, the candidate intra prediction mode may be determined to be a predetermined intra prediction mode, based on the prediction mode of the neighboring block being an MIP mode.
1. An image decoding method performed by an image decoding apparatus, the image decoding method comprising:
identifying a prediction mode of a current block;
identifying whether an intra prediction mode of the current block is an MIP (matrix-based intra prediction) mode, based on the prediction mode of the current block being the intra prediction mode;
determining a candidate intra prediction mode for the current block based on a prediction mode of a neighboring block located around the current block, based on the intra prediction mode of the current block not being the MIP mode;
generating a candidate intra prediction mode list of the current block based on the candidate intra prediction mode; and
determining the intra prediction mode of the current block based on the candidate intra prediction mode list,
wherein the candidate intra prediction mode is determined to be a predetermined intra prediction mode, based on the prediction mode of the neighboring block being an MIP mode,
wherein the candidate intra prediction mode is determined to be the predetermined intra prediction mode, based on the neighboring block not being available.
2. The image decoding method of claim 1 , wherein the predetermined intra prediction mode is a planar mode.
3. The image decoding method of claim 1 ,
wherein whether the prediction mode of the neighboring block is the MIP mode is determined based on an MIP mode indicator for the neighboring block, and
wherein the MIP mode indicator is obtained from a bitstream.
4. The image decoding method of claim 1 ,
wherein the candidate intra prediction mode list is generated based on a first candidate intra prediction mode and a second candidate intra prediction mode,
wherein the first candidate intra prediction mode is determined based on a prediction mode of a first neighboring block located around the current block, and
wherein the second candidate intra prediction mode is determined based on a prediction mode of a second neighboring block located around the current block.
5. The image decoding method of claim 4 , wherein, based on the first candidate intra prediction mode and the second candidate intra prediction mode being the same and the first candidate intra prediction mode being an intra prediction mode having a greater value than a prediction mode value specifying a DC mode, the candidate intra prediction mode list is determined to include the value of the first candidate intra prediction mode.
6. The image decoding method of claim 4 , wherein the candidate intra prediction mode list is determined to have a predetermined candidate intra prediction mode, based on both the prediction mode of the first neighboring block and the prediction mode of the second neighboring block being an MIP mode.
7. The image decoding method of claim 6 , wherein the predetermined candidate intra prediction mode comprises at least one of a DC mode or a vertical mode.
8. The image decoding method of claim 4 , wherein, based on the prediction mode of the first neighboring block being an MIP mode, the first candidate intra prediction mode and the second candidate intra prediction mode being different from each other and the second candidate intra prediction mode being an intra prediction mode having a greater value than a prediction mode value specifying a DC mode, the candidate intra prediction mode list is determined to include the second candidate intra prediction mode.
9. The image decoding method of claim 1 , wherein the determining the intra prediction mode of the current block based on the candidate intra prediction mode list is performed by determining any one of candidate intra prediction modes included in the candidate intra prediction mode list to be an intra prediction mode of the current block based on an intra prediction mode indicator obtained from a bitstream.
10. The image decoding method of claim 1 , comprising:
determining a reference mode for determining an intra prediction mode of a chroma block corresponding to the current block; and
determining the intra prediction mode of the chroma block based on the reference mode,
wherein the current block is a luma block, and
wherein the reference mode is determined to be a planar mode based on the intra prediction mode of the current block being the MIP mode.
11. The image decoding method of claim 10 , wherein the intra prediction mode of the chroma block is determined to be the reference mode.
12. The image decoding method of claim 11 , wherein the reference mode is determined based on the intra prediction mode of the current block, based on the intra prediction mode of the current block not being the MIP mode.
13. An image encoding method performed by an image encoding apparatus, the image encoding method comprising:
identifying a prediction mode of a current block;
identifying whether an intra prediction mode of the current block is an MIP (matrix-based intra prediction) mode, based on the prediction mode of the current block being the intra prediction mode;
determining a candidate intra prediction mode based on a prediction mode of a neighboring block located around the current block, based on the intra prediction mode of the current block not being the MIP mode;
generating a candidate intra prediction mode list of the current block based on the candidate intra prediction mode; and
encoding an intra prediction mode indicator specifying the intra prediction mode of the current block based on the candidate intra prediction mode list,
wherein the candidate intra prediction mode is determined to be a predetermined intra prediction mode, based on the prediction mode of the neighboring block being an MIP mode,
wherein the candidate intra prediction mode is determined to be the predetermined intra prediction mode, based on the neighboring block not being available.
14. A non-transitory computer-readable recording medium storing a bitstream generated by the image encoding method of claim 13 .
15. A method of transmitting a bitstream generated by an image encoding method, the image encoding method comprising:
identifying a prediction mode of a current block;
identifying whether an intra prediction mode of the current block is an MIP (matrix-based intra prediction) mode, based on the prediction mode of the current block being the intra prediction mode;
determining a candidate intra prediction mode based on a prediction mode of a neighboring block located around the current block, based on the intra prediction mode of the current block not being the MIP mode;
generating a candidate intra prediction mode list of the current block based on the candidate intra prediction mode; and
encoding an intra prediction mode indicator specifying the intra prediction mode of the current block based on the candidate intra prediction mode list,
wherein the candidate intra prediction mode is determined to be a predetermined intra prediction mode, based on the prediction mode of the neighboring block being an MIP mode,
wherein the candidate intra prediction mode is determined to be the predetermined intra prediction mode, based on the neighboring block not being available.