Non-local refinement of directional intra predictor

The key objective in video coding is to eliminate redundant information. To address spatial redundancy, which is a representative redundancy, intra prediction utilizes spatial neighboring information. to use spatial neighboring sample information, techniques such as directional prediction, non-directional prediction, and offline-trained matrix-based prediction is currently applied in beyond VVC capability. To achieve better intra prediction in beyond VVC capability, both improvements to the existing modes and the adoption of new tools have been implemented. Despite the improvments of existing modes and the adoption of new tools in beyond VVC capability, tools utilizing the directional intra mode still only rely on the local information for the prediction of the current block. To improve the predictors of the tools using the directional intra mode, this paper proposes a non-local refinement method of the predictor coded by directional intra mode. Block vector from adjacent sample of the current block is utilized to construct a non-local neightbor area for the refinement of the predictor. Using the constructed non-local neighbor area, the refinement process for the predictor is conducted. the refinement is performed on a row and column basis by using predefined weights. Our experiment is conducted under the all intra configuration using the first 65 frames of natural content sequences of ECM-11.0. The experiment result shows that there was 0.02% gain in Y channel, but 0.04% and 0.09% loss in Cb and Cr channel.