Video signal processing method and device for intra prediction of coding or prediction blocks based on sample position based parameters

A method of encoding a video, the method comprising:

• generating a prediction sample of a current block based on an intra prediction mode of the current block;
• determining whether to modify the prediction sample or not;
• when it is determined to modify the prediction sample, deriving a first sample position based parameter for modifying the prediction sample in the prediction block;
• obtaining a modified prediction sample based on the prediction sample and the first sample position based parameter;
• obtaining a residual sample of the current block;
• and
• obtaining a reconstruction sample based on the modified prediction sample and the residual sample,
• wherein the first sample position based parameter being derived based on a multiplication of a reference sample adjacent to the current block and a first weight,
• wherein the first weight is derived by shifting a constant value based on a value derived based on a coordinate of the prediction sample and a shift parameter,
• wherein the shift parameter is derived based on a width and a height of the current block, and
• wherein the shift parameter is derived based on a sum of log2 width and log2 height.

A non-transitory computer readable recoding medium comprising a video signal bitstream, the video signal bitstream included in the recoding medium is encoded by a video encoding method comprising:

• generating a prediction sample of a current block based on an intra prediction mode of the current block;
• determining whether to modify the prediction sample or not;
• when it is determined to modify the prediction sample, deriving a first sample position based parameter for modifying the prediction sample in the prediction block;
• obtaining a modified prediction sample based on the prediction sample and the first sample position based parameter;
• obtaining a residual sample of the current block;
• and
• obtaining a reconstruction sample based on the modified prediction sample and the residual sample,
• wherein the first sample position based parameter being derived based on a multiplication of a reference sample adjacent to the current block and a first weight,
• wherein the first weight is derived by shifting a constant value based on a value derived based on a coordinate of the prediction sample and a shift parameter,
• wherein the shift parameter is derived based on a width and a height of the current block, and
• wherein the shift parameter is derived based on a sum of log2 width and log2 height.