Sub-pixel motion estimation with 3-D recursive search block-matching

Recently the 3-D Recursive Search Block-Matching algorithm was introduced as a high quality, low-cost, true-motion estimation method suitable for critical field rate conversion applications. In this article an extension of the algorithm is presented that provides a sub-pixel accuracy of the estimated motion vectors. This significantly broadens the applicability of the algorithm in the area of interlaced-to-sequential scan conversion and coding. The extension is such that it hardly adds any calculational complexity, which implies that the attractiveness of the algorithm for a VLSI implementation remains high. Even more, a simplified version of the algorithm, the Y-prediction block-matcher, is suggested that offers sub-pixel accuracy, a large range of motion vectors, and an extremely low complexity requiring only four candidate vectors per block. An evaluation of this estimator is included in the paper.