Image signal encoding/decoding method and non-transitory computer-readable medium
View Patent ↗An image decoding method according to the present disclosure comprises the steps of: generating a merge candidate list in a current block; specifying one of a plurality of merge candidates included in the merge candidate list; deriving a first affine seed vector and a second affine seed vector of the current block on the basis of a first affine seed vector and a second affine seed vector of the specified merge candidate; deriving an affine vector for a subblock in the current block, using the first affine seed vector and the second affine seed vector of the current block; and performing motion compensation prediction for the subblock on the basis of the affine vector.
1. A video decoding method, comprising:
in response to that a top boundary of a current block is in contact with a top boundary of a coding tree unit of the current block, obtaining a first affine seed vector of a bottom-left corner control point of a top affine neighboring block of a current block and a second affine seed vector of a bottom-right corner control point of the top affine neighboring block;
deriving a third affine seed vector of the current block and a fourth affine seed vector of the current block based on the first affine seed vector and the second affine seed vector of the top affine neighboring block;
deriving an affine vector for a subblock in the current block by using the third affine seed vector of the current block and the fourth affine seed vector of the current block, wherein the subblock is a region of a size smaller than that of the current block; and
performing a motion compensation prediction for the subblock based on the affine vector.
2. The method of claim 1 , wherein a sample positioned on a right side of a bottom-right sample of a bottom-right subblock of the top affine neighboring block is set as a reference sample for the bottom-right corner control point, and the bottom-right subblock is set as an affine subblock for the bottom-right corner control point.
3. The method of claim 1 , wherein a sample positioned on a left side of a bottom-left sample of a bottom-left subblock of the top affine neighboring block is set as a reference sample for the bottom-left corner control point, and the bottom-left subblock is set as an affine subblock for the bottom-left corner control point.
4. A video encoding method, comprising:
in response to that a top boundary of a current block is in contact with a top boundary of a coding tree unit of the current block, obtaining a first affine seed vector of a bottom-left corner control point of a top affine neighboring block of a current block and a second affine seed vector of a bottom-right corner control point of the top affine neighboring block;
deriving a third affine seed vector of the current block and a fourth affine seed vector of the current block based on the first affine seed vector and the second affine seed vector of the top affine neighboring block;
deriving an affine vector for a subblock in the current block by using the third affine seed vector of the current block and the fourth affine seed vector of the current block, wherein the subblock is a region of a size smaller than that of the current block; and
performing a motion compensation prediction for the subblock based on the affine vector.
5. The method of claim 4 , wherein a sample positioned on a right side of a bottom-right sample of a bottom-right subblock of the top affine neighboring block is set as a reference sample for the bottom-right corner control point, and the bottom-right subblock is set as an affine subblock for the bottom-right corner control point.
6. The method of claim 4 , wherein a sample positioned on a left side of a bottom-left sample of a bottom-left subblock of the top affine neighboring block is set as a reference sample for the bottom-left corner control point, and the bottom-left subblock is set as an affine subblock for the bottom-left corner control point.
7. A video decoder configured to perform following operations:
in response to that a top boundary of a current block is in contact with a top boundary of a coding tree unit of the current block, obtaining a first affine seed vector of a bottom-left corner control point of a top affine neighboring block of a current block and a second affine seed vector of a bottom-right corner control point of the top affine neighboring block;
deriving a third affine seed vector of the current block and a fourth affine seed vector of the current block based on the first affine seed vector and the second affine seed vector of the top affine neighboring block;
deriving an affine vector for a subblock in the current block by using the third affine seed vector of the current block and the fourth affine seed vector of the current block, wherein the subblock is a region of a size smaller than that of the current block; and
performing a motion compensation prediction for the subblock based on the affine vector.
8. The video decoder of claim 7 , wherein a sample positioned on a right side of a bottom-right sample of a bottom-right subblock of the top affine neighboring block is set as a reference sample for the bottom-right corner control point, and the bottom-right subblock is set as an affine subblock for the bottom-right corner control point.
9. The video decoder of claim 7 , wherein a sample positioned on a left side of a bottom-left sample of a bottom-left subblock of the top affine neighboring block is set as a reference sample for the bottom-left corner control point, and the bottom-left subblock is set as an affine subblock for the bottom-left corner control point.