Method of classifying signals, especially image signals

Abstract

Artificial Intelligence (AI) techniques are used for processing data having multiple possible values, for example, gray-scale values of pixels of an image. This is useful in scanning of digitally-coded image data to detect anomalies, for example defects in some of a series of manufactured products. The preferred processing apparatus has either one processing channel or multiple parallel processing channels. The apparatus samples or scans incoming signals to produce a matrix of scan values, selects subsets of the scan values to define samples, extracts at least one feature, such as mean image brightness (MM), activity (MA), gradient absolute value (MG) and/or gradient direction (MD) from each sample, uses the at least one feature as an address to retrieve, from a table, a corresponding probability-of-occurrence value, derives, from the probability-of-occurrence values of a plurality of the samples, a decision value, and compares the decision value with a predetermined threshold value. The probability-of-occurrence values are stored in the table during a 'learning' procedure.