Intra angular prediction with weight function and modification filter

Standardization of a new video coding standard, High Efficiency Video Coding (HEVC version 1), has been completed and its compression ratio is twice as much as that of H.264/AVC under the condition of the same subjective quality. In HEVC, many coding tools contribute to the improvement of the coding efficiency. One example is the intra angular prediction mode that has finer prediction directions compared to H.264/AVC. In this paper, we propose two modified intra angular prediction methods: (A) reference pixels that are closer to the predicted pixels than the original reference pixels are exploited, and (B) a blending filter similar to the filter used in the intra DC mode is enhanced and applied. In the proposed method, the predicted signals of the angular prediction mode are generated by blending the predicted signals of the selected angular prediction mode and those of the other mode which has the opposite prediction direction. The overall average coding gain against the HM9.0.1 RExt 1.0 anchor was about 0.5% for the combined method. The maximum coding gain was about 1.0%. The average encoding and decoding run-times were 104.1% and 103.4%, respectively.