关键词: 运动估计, UMHexagons算法, 自适应十字形模板

Abstract: This paper proposes an adaptive unsymmetrical cross search pattern to perform fast block matching.The pattern solves the disadvantage of single pattern in searching vertical moving objects.It predicts the motion of the current block and chooses the pattern adaptively.This enables us to add the number of search points more efficiently and thus improves the search speed.Meanwhile，the new algorithm also adopts the advanced-stop criteria and linear search technology.Simulation results show that the new algorithm can reduce the search time above 20% compared with the UMHexagons algorithm adopted by H.264 standard.

Key words: motion estimation, UMHexagons algorithm, adaptive unsy-mmetrical cross search pattern