Fast Block Matching Algorithm in Walsh Hadamard Domain

A fast block matching algorithm, namely Fast Walsh Search, is proposed for motion estimation in block-based video coding. In our approach, target blocks in current frame and their candidates in reference frame are projected onto Walsh Hadamard domain, allowing early rejection of mismatch candidates to reduce computation requirement. Moreover, we introduce a new method called block pyramid matching that re-uses many previous calculations to further lessen the computation load of our approach. Experimental results show that the proposed algorithm can achieve more accurate motion estimation than the popular three-step-search and diamond search with slight increase in computation requirement only.