Method and apparatus for processing video signal
A method for decoding a video according to the present invention may comprise: determining an intra prediction mode of a current block, deriving reference samples from neighboring samples of the current block, obtaining a first prediction sample for the current block, based on the intra prediction mode and the reference samples, determining an offset for the first prediction sample, and obtaining a second prediction sample by applying the offset to the first prediction sample.
1. A method for decoding a video, comprising:
determining an intra prediction mode of a current block;
obtaining an intra prediction sample of the current block, based on the intra prediction mode of the current block; and
determining whether to modify the intra prediction sample of the current block,
wherein a determination of whether to modify the intra prediction sample is based on whether the intra prediction mode of the current block is one of pre-defined intra prediction modes,
wherein the pre-defined intra prediction modes comprise a planar mode,
wherein, in response to a determination of the intra prediction mode of the current block is the planar mode, the intra prediction sample of the current block is modified based on an offset,
wherein the offset is derived based on a weighted sum of a first reference sample and a second reference sample adjacent to the current block, and
wherein a first weight applied to the first reference sample is determined based on an x-coordinate of the intra prediction sample and a variable obtained based on a size of the current block, and a second weight applied to the second reference sample is determined based on a y-coordinate of the intra prediction sample and the variable.
2. The method according to claim 1 , wherein:
in a first region in the current block, modified intra prediction sample is output while, in a second region in the current block, an intra prediction sample obtained by intra prediction is output as it is, and
a pattern formed by the first region and the second region is different between when the intra prediction mode of the current block is the planar mode and when the intra prediction mode of the current block is a directional mode.
3. The method according to claim 2 , wherein:
the pattern of the current block is selected among a plurality of candidate patterns, and
the plurality of candidate patterns comprises a polygonal pattern under which the second region is defined as a block whose a width and a height is less than the current block and the first region is defined as a remaining region of the current block excluding the second region.
4. The method according to claim 1 , wherein:
the first reference sample is a left neighboring sample on a same horizontal line as the intra prediction sample and the second reference sample is a top neighboring sample on a same vertical line as the intra prediction sample.
5. The method according to claim 1 , wherein:
when the intra prediction mode of the current block is a vertical mode, the intra prediction sample is modified by using an offset derived based on a difference between neighboring samples adjacent to the current block, and
a number of lines in which intra prediction samples to be modified are included is determined based on a size of the current block.
6. A method for encoding a video, comprising:
determining an intra prediction mode of a current block;
obtaining an intra prediction sample of the current block, based on the intra prediction mode of the current block; and
determining whether to modify the intra prediction sample of the current block,
wherein a determination of whether to modify the intra prediction sample is based on whether the intra prediction mode of the current block is one of pre-defined intra prediction modes,
wherein the pre-defined intra prediction modes comprise a planar mode,
wherein, in response to a determination of the intra prediction mode of the current block is the planar mode, the intra prediction sample of the current block is modified based on an offset,
wherein the offset is derived based on a weighted sum of a first reference sample and a second reference sample adjacent to the current block, and
wherein a first weight applied to the first reference sample is determined based on an x-coordinate of the intra prediction sample and a variable obtained based on a size of the current block, and a second weight applied to the second reference sample is determined based on a y-coordinate of the intra prediction sample and the variable.
7. The method according to claim 6 , wherein:
in a first region in the current block, modified intra prediction sample is output while, in a second region in the current block, an intra prediction sample obtained by intra prediction is output as it is, and
a pattern formed by the first region and the second region is different between when the intra prediction mode of the current block is the planar mode and when the intra prediction mode of the current block is a directional mode.
8. The method according to claim 7 , wherein:
the pattern of the current block is selected among a plurality of candidate patterns, and
the plurality of candidate patterns comprises a polygonal pattern under which the second region is defined as a block whose a width and a height is less than the current block and the first region is defined as a remaining region of the current block excluding the second region.
9. The method according to claim 6 , wherein:
the first reference sample is a left neighboring sample on a same horizontal line as the intra prediction sample and the second reference is a top neighboring sample on a same vertical line as the intra prediction sample.
10. The method according to claim 6 , wherein:
when the intra prediction mode of the current block is a vertical mode, the intra prediction sample is modified by using an offset derived based on a difference between neighboring samples adjacent to the current block, and
a number of lines in which intra prediction samples to be modified are included is determined based on a size of the current block.
11. An apparatus for decoding a video, comprising:
an intra prediction unit configured to:
determine an intra prediction mode of a current block;
obtain an intra prediction sample of the current block, based on the intra prediction mode of the current block; and
determine whether to modify the intra prediction sample of the current block,
wherein a determination of whether to modify the intra prediction sample is based on whether the intra prediction mode of the current block is one of pre-defined intra prediction modes,
wherein the pre-defined intra prediction modes comprise a planar mode,
wherein, in response to a determination of the intra prediction mode of the current block is the planar mode, the intra prediction sample of the current block is modified based on an offset,
wherein the offset is derived based on a weighted sum of a first reference sample and a second reference sample adjacent to the current block, and
wherein a first weight applied to the first reference sample is determined based on an x-coordinate of the intra prediction sample and a variable obtained based on a size of the current block, and a second weight applied to the second reference sample is determined based on a y-coordinate of the intra prediction sample and the variable.
12. A non-transitory computer-readable medium for storing data associated with a video signal, comprising:
a data stream stored in the non-transitory computer-readable medium, the data stream being encoded by an encoding method which comprising:
determining an intra prediction mode of a current block;
obtaining an intra prediction sample of the current block, based on the intra prediction mode of the current block; and
determining whether to modify the intra prediction sample of the current block,
wherein a determination of whether to modify the intra prediction sample is based on whether the intra prediction mode of the current block is one of pre-defined intra prediction modes,
wherein the pre-defined intra prediction modes comprise a planar mode,
wherein, in response to a determination of the intra prediction mode of the current block is the planar mode, the intra prediction sample of the current block is modified based on an offset,
wherein the offset is derived based on a weighted sum of a first reference sample and a second reference sample adjacent to the current block, and
wherein a first weight applied to the first reference sample is determined based on an x-coordinate of the intra prediction sample and a variable obtained based on a size of the current block, and a second weight applied to the second reference sample is determined based on a y-coordinate of the intra prediction sample and the variable.