Image encoder, image decoder, image encoding method, image decoding method and image encoding/decoding system

摘要

It is an object of the invention to obtain a video encoder and a video decoder performing a highly.accurate prediction of a picture, transformed by other than translation, within a short.processing time in a small-scaled circuit. A video encoder for performing compression encoding of an input picture includes motion compensated prediction means for performing interframe motion detection. The motion compensated prediction means has a motion detector including a transformed block matching unit for transforming a reference picture portion into a picture portion having a predefined shape for performing motion detection and a motion compensator including a corresponding pel determinator for determining integer pels of real sample points of the transformed reference picture portion corresponding to an integer pel of the input picture block according to the motion parameters supplied from the motion detector as a result of the comparison so as to supply prediction picture data. The video encoder of the present invention can be combined with a video decoder having a motion compensator which performs the same operations as those in the video encoder to configure a video encoding and decoding system. Further, the video decoder uses half-pels of the reference picture in the motion compensator as well as integer pels, computes pel positions using plural motion vectors, and transforms the obtained pel value into a predefined form by the transformation pattern.