This paper presents a fast hierarchical feature matching-motion estimation scheme (HFM-ME) that can be used in H.263, H.261, MPEG 1, MPEG 2, and HDTV applications. In the HFM-ME scheme, the sign truncated feature (STF) is defined and used for block template matching, as opposed to the pixel intensity values used in conventional block matching methods. The STF extraction process can be considered as a zero-crossing phase detection with the mean as the bias and binary sign pattern as the phase deviation. Using the STF definition, a data block can be represented by a mean and a set of binary features 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 full-search block matching ME because binary phase matching only involves Boolean logic operations. This feature also significantly reduces the data transfer time between the frame buffer and motion estimator. The proposed HFM-ME algorithm is implemented and compared with the conventional full-search block matching schemes. Our test results using three full-motion MPEG sequences indicate that the performance of the HFM-ME is comparable with the full-search block matching under the same search ranges, however, HFM-ME can be implemented about 64 times faster than the conventional full-search schemes. The proposed scheme can be combined with other fast algorithms to further reduce the computational complexity, at the expense of picture quality.
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