Block-adaptive interpolation filter for sub-pixel motion compensation

Adaptive interpolation filtering for sub-pel motion estimation is one of several superior techniques of ITU-T KTA CODEC to the H.264/AVC CODEC. However, the adaptive interpolation filtering has a limitation in coding efficiency because of its frame-based update strategy of filter coefficients. In order to overcome such a problem, this paper presents a block-adaptive interpolation filtering using learning-based super-resolution. The proposed block-adaptive interpolation filtering for quarter-pel motion estimation consists of two steps: two-times up-scaling of half-pel accuracy and subsequent two-times up-scaling of quarter-pel accuracy. The dictionary optimized for each step is employed to produce the precise up-scaled blocks. Simulation results show that the proposed algorithm improves coding efficiency up to 5.3% in comparison with the previous adaptive interpolation filtering for KTA.