1. A method for determining a metric for use in motion estimation in motion compensated video coding of a scene comprising frames, the method comprising: employing at least one Single Instruction Multiple Data (SIMD) processor for determining the metric, comparing a first image block contained in a reference frame and a second image block contained in a current frame, comprising: generating a pattern matrix having the same number of rows and columns as the first and second image blocks, said pattern matrix specifying a subset of pixels to be selected in the first and second image blocks; the subset of pixels being divided into a plurality of groups of successive pixels, each group of successive pixels comprising an uninterrupted sequence of two or more pixels in a row, a number of pixels in said each group of successive pixels being selected so that to be operable in a single instruction of the SIMD processor; positions of the groups of successive pixels within the first and second image blocks being selected so as to maximize a span of block coverage, wherein: vertical distances between any two adjacent groups are substantially equal; and horizontal distances between any two adjacent groups are also substantially equal; obtaining characteristics of pixels in the subset of pixels for the first and second images blocks; and determining the metric based on the obtained characteristics.