Intra prediction mode based image processing method, and apparatus therefor
The present invention provides an image processing method on the basis of an intra prediction mode and an apparatus therefor. Specifically, a method for processing an image on the basis of an intra prediction mode may comprise the steps of: identifying whether weighted intra prediction is allowed for a current block and whether the weight intra prediction is applied to the current block; identifying whether reference sample filtering is applied to the current block when the weighted intra prediction is not allowed for the current block or when the weighted intra prediction is not applied to the current block; and performing reference sample filtering of reference samples neighboring the current block when the reference sample filtering is applied.
1. A method of processing an image based on an intra prediction mode, the method comprising:
identifying, by a processor, whether a weighted intra prediction is allowed in a current block and whether the weighted intra prediction is applied to the current block;
identifying, by the processor, whether reference sample filtering is applied to the current block when the weighted intra prediction is not allowed in the current block or the weighted intra prediction is not applied to the current block;
determining, by the processor, not to perform the reference sample filtering on the current block when the weighted intra prediction is allowed in the current block and the weighted intra prediction is applied to the current block; and
performing, by the processor, reference sample filtering on reference samples neighboring the current block when the reference sample filtering is applied.
2. The method of claim 1 ,
wherein a syntax element indicating whether the weighted intra prediction is allowed is signaled in a sequence, picture or slice unit.
3. The method of claim 1 ,
wherein identifying whether the reference sample filtering is applied to the current block comprises identifying whether an intra prediction mode of the current block is not a DC mode and the intra prediction mode of the current block is one of directional modes of a predetermined angular range.
4. The method of claim 3 ,
wherein performing the reference sample filtering comprises determining a filter used for the reference sample filtering by comparing a difference value between reference samples at specific locations neighboring the current block with a predetermined threshold.
5. The method of claim 1 ,
wherein identifying whether the reference sample filtering is applied to the current block comprises identifying a reference sample adaptive filtering flag.
6. The method of claim 1 ,
wherein the weighted intra prediction is a position-dependent intra prediction combination.
7. The method of claim 1 ,
wherein identifying whether the reference sample filtering is applied to the current block comprises identifying whether the reference sample filtering is applied to the current block based on at least one of a size of the current block, a number of transform coefficients not 0 within a residual block of the current block, a size of the residual block of the current block or whether a non-separable secondary transform is applied to the current block.
8. An apparatus for processing a video based on an intra prediction mode, the apparatus comprising:
a processor configured to:
identify whether a weighted intra prediction is allowed in a current block and whether the weighted intra prediction is applied to the current block;
identify whether reference sample filtering is applied to the current block when the weighted intra prediction is not allowed in the current block or the weighted intra prediction is not applied to the current block;
determine not to perform the reference sample filtering on the current block when the weighted intra prediction is allowed in the current block and the weighted intra prediction is applied to the current block; and
perform reference sample filtering on reference samples neighboring the current block when the reference sample filtering is applied.