Improved intra angular prediction by DCT-based interpolation filter

This paper proposes a new intra angular prediction method exploiting interpolation technique whose tap length is greater than two. Intra prediction direction of High efficiency video coding (HEVC) standard is finer than that of H.264/AVC. A method to make reference samples for the intra angular prediction plays an important role in the coding performance. In this proposal, the reference samples are generated by the conventional 2-tap filter or a 4-tap DCT-based interpolation filter. The proposal improves the intra prediction performance especially for small prediction units such as 4×4 and 8×8. The average coding gains against the anchor of HEVC test model (HM5.0) were about 0.3%, 0.5%, and 0.5% for Y, Cb, and Cr. The maximum coding gains were about 1.8%, 2.5%, and 3.4% for each component. The average run-times of encoding and decoding were about 99.87% and 99.49%, respectively.