Patent US 4,754,493

A set of stores contains reference information representing a reference pattern. A scene is scanned and information derived from each of a succession of portions of the scene is fed to the stores which produce correlation signals if the scene information of that portion correlates with the reference information. The position of the portion of the scene which is fed to the stores is tracked, and the position associated with the highest correlation score is used as a representation of the position in the scene of the reference pattern.