In this paper, we propose a fast block motion estimation scheme by exploiting the correlations of motion vectors (MV) existing in spatially- and temporally-adjacent as well as hierarchically-related blocks. The basic idea is to use the information obtained from the corresponding block at a coarser resolution level and spatio-temporal neighboring blocks at the same level in order to select a good set of initial MV candidates and then perform further local search to find the best matching MV. In order to further reduce computational complexity, the sign pattern vector (SPV) is defined and used for block matching, as opposed to the pixel intensity values used in the conventional block matching methods. By using the SPV definition, a data block can be presented by a mean and a set of binary sign patterns with a much reduced data set. The block matching motion estimation is then divided into mean matching and binary phase matching. The proposed technique enables a significant reduction in computational complexity compared with the conventional block matching motion estimation (ME) because binary phase matching only involves Boolean logic operations. This scheme also significantly reduces the data transfer time between the frame buffer and motion estimator. Our test results indicate that the performance of the proposed scheme is comparable with the full-search block matching under the same search ranges, however, the proposed scheme has a speed-up factor ranging from 250 to 370 in comparison with full search.
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