A cross octagonal search algorithm for fast block motion estimation

A cross octagonal search algorithm (COSA) is proposed in this paper to perform block motion estimation in video sequence compression. In contrast with the classical fast block motion algorithm, cross and octagonal search pattern is adopted in search process in this algorithm. Based on the characteristic of motion vector's cross center biased distribution, the correlation of the ending points in the searching pattern can be reduced. So in this paper octagonal pattern is used and cross pattern is used in COSA to reduce the number of searching points. The experimental results show that the cross octagonal search algorithm performs better than HEXBS and hybrid unsymmetrical cross multi-hexagon-grid search (UMHexagonS) which is adopted by joint modal for near four years and still be used in the latest version JM9.6.