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Abstract

An image sequence transmission method and apparatus transmit a sequence of successive images over a bandwidth limited channel. The transmitter has a motion estimator for estimating the motion displacement between successive image frames of the sequence. The motion estimator divides each image into nonoverlapping blocks, each block including a plurality of picture elements. The apparatus then successively selects, in accordance with a steepest descent estimation technique, an initial value of a motion vector displacement for each successive block. Thereafter, an iterative process determines using the steepest descent approach, successive values of the motion displacement vector for a block and the iteration process is terminated when an iteration error measure, which is associated with the steepest descent method, is less than a predetermined threshold value. In particular embodiments of the invention, an adaptive approach is used wherein the step size parameter is incremented in accordance with a gradient error used in the steepest descent technique. In addition, methods and apparatus for determining an initial motion vector field value based upon of the motion displacements in adjacent blocks advantageously determine the initial displacement vector for a block.

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First Claim