Enhanced efficient Diamond Search algorithm for fast block motion estimation

In this paper, a modified diamond search (MDS) algorithm is proposed for fast motion estimation based on the well known diamond search (DS) algorithm. A set of computationally efficient algorithms that can be applied to any block matching algorithm and is applied to the DS as a study case achieves higher complexity reduction than DS algorithm without further relative PSNR (peak signal to noise ratio) degradation compared to full search (FS). First, dynamic internal stop search (DISS) algorithm is used to reduce the internal redundant SAD (sum of absolute difference) operations between the current and the candidate blocks using an accurate dynamic threshold. Second, a dynamic external stop search (DESS) greatly reduces the unnecessary operations by skipping all the irrelevant blocks in the search area. In addition, early search termination and adaptive pattern selections techniques are applied to the proposed MDS as initialization steps to achieve even higher complexity reduction. The accuracy of the proposed model threshold equations guarantee not to fall into a local minima. Experiments show that the proposed MDS algorithm reduces the computations greatly up to 99% and 20% compared with the conventional FS algorithm and DS respectively with no significant degradation in both the PSNR and the bit-rate.