Process and device for global motion estimation in a sequence of images and a computer program product therefor

Abstract

A process for realizing an estimate of global motion based on a sequence of subsequent video images, such as those received via an optical mouse (M) for the purposes of detecting its movement. Subsequent video images are represented by digital signals arranged in frames and for each estimate of a frame with respect to another, the procedure provides operations for choosing, from amongst a series of vectors originating from linear combinations of motion vectors resulting from estimates of previous frames and/or constant vectors, a vector considered as the best match for estimating the motion occurring between the two frames, the said selection operation in turn including the operations of performing a virtual overlay of the two frames to be compared (T, T−1) mutually offset both horizontally and vertically by amounts identified by the motion vector subjected to testing, applying a selective grid of pixels to be subjected to testing, and calculating, for all pixels selected via the grid, a cost function to determine the effectiveness of the predictor, identifying the vector with the lowest cost function value as the best for the purposes of estimation.