Video coding using affine motion compensated prediction

The aim in variable block size and object based video coding is to motion compensate as large regions as possible. Whereas the translational motion model is adequate to motion compensate small regions even if the image sequence involves complex motion, it is no longer capable of delivering satisfactory results for large regions. A more sophisticated motion model is required in such regions. In this paper, we extend our previous approach by proposing a multiple layer video codec which uses affine model for large regions to improve motion compensation. The translational model is still used for small regions to reduce the bit overhead. A multi-resolution robust Hough transform based motion estimation technique is used to estimate the affine motion parameters. The experimental results show that the proposed method gives better results in terms of the bit rate under the same PSNR constraint for most of the tested sequences as compared with our previous approach and an implementation of the standard H.261.