Fast Half Pixel Motion Estimation Based on the Spatial Correlation

Abstract

Motion estimation is an important part of video encoding systems, because it can significantly affect the output quality of an encoded sequence. Most of the advanced techniques for motion estimation consist of two stages, the integer pixel motion estimation and the half pixel motion estimation. Although many fast integer pixel motion estimation algorithms have been developed, the performance of current methods for half pixel motion estimation still has room for improvement. In this paper, we propose a new algorithm for half pixel motion estimation which exploits the spatial correlation between integer and half pixle motion vectors. The proposed algorithm adaptively decides the search range of half pixel points considering the correlation of the motion vectors around the point of interest. The experiment results show that the proposed method outperforms most of existing methods in computaion time by reducing the number of search points with little or no degradation in image quality. Even when compared to the full half pixel search method, it shows the search point reducton upto 95% with only 0.01 ~ 0.09 (dB) degradation of image quality in terms of PSNR.