Vector-tracing algorithms for motion estimation in large search windows

Despite several efforts aimed at reducing the complexity, block-based motion estimation remains the most computationally demanding stage of video compression algorithms. This is particularly evident when sequences contain large displacements; very large search windows are needed to achieve high-quality coding when such critical conditions occur. This paper presents a new block-motion-estimation algorithm based on the systematic application of the tracing of motion trajectories on a modified genetic search heuristic. The described technique is able to provide motion estimates in very large search windows with optimal coding results. The complexity-reduction factor ranges up to more than two orders of magnitude. The technique can be applied to any macroblock-based video compression standard and to any group of picture structure