Adaptive interpolation filter for H.264/AVC

In order to reduce the bit-rate of video signals, current coding standards apply hybrid coding with motion-compensated prediction and transform coding of the prediction error. In former publications, it has been shown that aliasing components contained in an image signal, as well as motion blur are limiting the prediction efficiency obtained by motion compensation. In this paper, we show that the analytical calculation of an optimal interpolation filter at particular constraints is possible, resulting in total coding improvements of 20% at broadcast quality compared to the H.264/AVC High Profile. Furthermore, the spatial adaptation to local image characteristics enables further improvements of 0.15 dB for CIF sequences compared to globally adaptive filter or up to 0.6 dB, compared to the standard H.264/AVC. Additionally, we show that the presented approach is generally applicable, i.e., also motion blur can be exactly compensated, if particular constraints are fulfilled.