Intra block copy-based encoding/decoding method, device, and bitstream storage medium
An image encoding/decoding method and apparatus are disclosed. The image decoding method includes acquiring prediction mode information of a current block from a bitstream, decoding an intra block copy prediction mode of the current block using the prediction mode information of the current block, and reconstructing the current block based on the intra block copy prediction mode. The intra block copy prediction mode is at least one of a block copy based SKIP mode, a block copy based MERGE mode or a block copy based AMVP mode.
1. A method of decoding an image, the method comprising:
constructing a block vector candidate list of a current block;
deriving a block vector of the current block based on one of block vector candidates included in the block vector candidate list; and
obtaining prediction samples of the current block based on the block vector of the current block,
wherein constructing the block vector candidate list comprises,
in response to a number of block vector candidates included in the block vector candidate list being less than a maximum number, adding at least one of history-based block vector candidates included in a history-based block vector candidate list to the block vector candidate list; and
wherein whether a history-based block vector candidate is added to the block vector candidate list is determined by comparing the history-based block vector candidate with a block vector candidate already included in the block vector candidate list.
2. The method of claim 1 , wherein the history-based block vector candidates in the history-based block vector candidate list are derived from a block decoded prior to the current block.
3. The method of claim 2 , wherein whether the history-based block vector candidate list is updated with the block vector of the current block is determined based on a size of the current block.
4. The method of claim 3 , wherein when the size of the current block is 4×4, the history-based block vector candidate list is not updated with the block vector of the current block.
5. The method of claim 4 , wherein when the size of the current block is greater than 4×4, the history-based block vector candidate list is updated with the block vector of the current block.
6. The method of claim 1 , wherein the one of the block vector candidates is selected based on an L0 motion vector predictor flag, and
wherein when the maximum number of block vector candidates that can be included in the block vector candidate list is not greater than 1, decoding the L0 motion vector predictor flag is omitted, and a value of the L0 motion vector predictor flag is inferred to 0.
7. The method of claim 1 , wherein when a size of the current block is 4×4, the history-based block vector candidate is added to the block vector candidate list without inserting a spatial block vector candidate to the block vector candidate list.
8. A method of encoding an image, the method comprising:
constructing a block vector candidate list of a current block;
deriving a block vector of the current block based on one of block vector candidates included in the block vector candidate list; and
obtaining prediction samples of the current block based on the block vector of the current block,
wherein constructing the block vector candidate list comprises in response to a number of block vector candidates included in the block vector
candidate list being less than a maximum number, adding at least one of history-based block vector candidates included in a history-based block vector candidate list to the block vector candidate list; and
wherein whether a history-based block vector candidate is added to the block vector candidate list is determined by comparing the history-based block vector candidate with a block vector candidate already included in the block vector candidate list.
9. A non-transitory computer-readable recording medium storing a bitstream generated by the encoding method, wherein the encoding method comprising:
constructing a block vector candidate list of a current block;
deriving a block vector of the current block based on one of block vector candidates included in the block vector candidate list; and
obtaining prediction samples of the current block based on the block vector of the current block,
wherein constructing the block vector candidate list comprises
in response to a number of block vector candidates included in the block vector candidate list being less than a maximum number, adding at least one of history-based block vector candidates included in a history-based block vector candidate list to the block vector candidate list; and
wherein whether a history-based block vector candidate is added to the block vector candidate list is determined by comparing the history-based block vector candidate with a block vector candidate already included in the block vector candidate list.