DIGITAL DATA PROCESSING

A method of processing digital data in a digitised image matrix in order to detect the positions of any sharp intensity variations present in adjacent ones of the pixels representing said image, the method comprising the steps of comparing the intensity of each primary pixel with those of the secondary pixels which surround it, calculating whether said primary pixel can be classified as having a constant, and edge-like or a corner-like value, and collating this information to give positions of both edge and corner features which are present in said image matrix. The processing method can be used for example in detecting images, for instance in a burglar alarm system or for the cytological scanning of cell material.