Motion estimation and representation for arbitrarily shaped image regions

This paper discusses the problem of motion compensated prediction in a segmentation based video coding scheme. The problem is considered in the framework of a generic video coder utilizing spatial image segmentation and a polynomial model of the motion vector field for each image region. It is shown that very impressive reductions in prediction error can be achieved by this approach compared to traditional block matching. The cost of encoding the motion information is also addressed. We derive an analytical method for the reduction of the number of motion coefficients, which is optimal is the sense of the least increase in the prediction error. Finally, we derive a low complexity method for motion assisted merging of regions resulting from spatial segmentation which leads to a dramatic reduction in the number of regions.