Method and device for processing video signal

A method of decoding a video, the method comprising:

• determining an intra prediction mode of a current block based on a candidate list including a plurality of intra prediction mode candidates, at least one intra prediction mode candidate being derived by an intra prediction mode of a neighboring block adjacent to the current block, a number of intra prediction mode candidates included in the candidate list being more than 3;
• deriving reference samples of the current block;
• obtaining first prediction samples of the current block by performing intra prediction based on the intra prediction mode of the current block and the reference samples;
• and
• determining whether an update process is applied to the current block or not,
• wherein when it is determined to apply the update process, second prediction samples are obtained by modifying the first prediction samples using respective offsets,
• wherein, in a first sub-region in the current block, an offset is adaptively determined based on at least one reference sample adjacent to the current block,
• wherein, in a second sub-region in the current block, an offset is derived to 0 regardless of the at least one reference sample adjacent to the current block,
• wherein at least one of a size or a shape of the first sub-region is different between when the intra prediction mode of the current block is a non-directional mode and when the intra prediction mode of the current block is a directional mode, and
• wherein at least one of a size or a shape of the second sub-region is different between when the intra prediction mode of the current block is a non-directional mode and when the intra prediction mode of the current block is a directional mode.

A method of encoding a video, the method comprising:

• determining an intra prediction mode of a current block based on a candidate list including a plurality of intra prediction mode candidates, at least one intra prediction mode candidate being derived by an intra prediction mode of a neighboring block adjacent to the current block, a number of intra prediction mode candidates included in the candidate list being more than 3;
• deriving reference samples of the current block;
• obtaining first prediction samples of the current block by performing intra prediction based on the intra prediction mode of the current block and the reference samples;
• and
• determining whether an update process is applied to the current block or not,
• wherein when it is determined to apply the update process, second prediction samples are obtained by modifying the first prediction samples using respective offsets,
• wherein, in a first sub-region in the current block, an offset is adaptively determined based on at least one reference sample adjacent to the current block,
• wherein, in a second sub-region in the current block, an offset is derived to 0 regardless of the at least one reference sample adjacent to the current block,
• wherein at least one of a size or a shape of the first sub-region is different between when the intra prediction mode of the current block is a non-directional mode and when the intra prediction mode of the current block is a directional mode, and
• wherein at least one of a size or a shape of the second sub-region is different between when the intra prediction mode of the current block is a non-directional mode and when the intra prediction mode of the current block is a directional mode.

A non-transitory computer-readable medium for storing computer-readable instructions such that, when executed, cause a process of a computer to perform a method of encoding a video, the method comprising:

• determining an intra prediction mode of a current block based on a candidate list including a plurality of intra prediction mode candidates, at least one intra prediction mode candidate being derived by an intra prediction mode of a neighboring block adjacent to the current block, a number of intra prediction mode candidates included in the candidate list being more than 3;
• deriving reference samples of the current block;
• obtaining first prediction samples of the current block by performing intra prediction based on the intra prediction mode of the current block and the reference samples;
• and
• determining whether an update process is applied to the current block or not,
• wherein when it is determined to apply the update process, second prediction samples are obtained by modifying the first prediction samples using respective offsets,
• wherein, in a first sub-region in the current block, an offset is adaptively determined based on at least one reference sample adjacent to the current block,
• wherein, in a second sub-region in the current block, an offset is derived to 0 regardless of the at least one reference sample adjacent to the current block,
• wherein at least one of a size or a shape of the first sub-region is different between when the intra prediction mode of the current block is a non-directional mode and when the intra prediction mode of the current block is a directional mode, and
• wherein at least one of a size or a shape of the second sub-region is different between when the intra prediction mode of the current block is a non-directional mode and when the intra prediction mode of the current block is a directional mode.