快速运动估计UMHexagonS算法的探讨与改进

视频编码标准H.264已经正式采纳了UMHexagonS算法作为整像素的快速运动估计算法。该算法的运算量相对于快速全搜索算法可节约90%以上,同时能保持较好的率失真性能。文章对UMHexagonS算法进行了介绍,对其特点及造成其独特优越性能的原因进行了初步分析,并提出了一种改进方法,即在预测起点处增加一个内容自适应的中止搜索阈值判断,以判断是否可立即结束搜索。模拟实验表明,相比原算法,改进后的算法明显减少了搜索点数,并保持了原算法率失真特性良好的特点。

An Improvement on the Motion Estimation Algorithm: UMHexagonS

The video coding standards H.264 have adopted Unsymmetrical cross Multi Hexagon grid Search (UMHexagonS) algorithm for integer pels motion estimation.UMHexagonS algorithm shows very good capability in keeping the rate distortion performance,as well as a great computation reduction up to 90% compared to Fast Full Search can be achieved.However,further investigation on fast motion estimation method is still necessary.In this paper,based on the study of the principles of the UMHexagonS algorithm,an improved method is proposed,in which the idea of a new adaptive factor is introduced in initial search point prediction step for early termination.Simulation Results show that the improved UMHexagonS algorithm can averagely reduce more than 10% of search points with minimal loss in bitrate and reconstructed quality compared with those of the original UMHexagonS algorithm.