1. An artificial neural network based system adapted to process an input pattern to generate an output pattern related thereto but having a different number of components than the input pattern; said system comprising: means for generating input patterns; an artificial neural network composed of neurons capable of storing input patterns as prototypes with a category associated therewith in the learning phase; memory means configured for storing an intermediate pattern for each stored prototype wherein the components of said intermediate pattern are the coefficients allowing determination of the estimated values of the output pattern, and outputting this intermediate pattern upon receipt of the corresponding category; and processor means for receiving said input and intermediate patterns and for processing said input and intermeidate patterns them in order to produce said output pattern in the recognition phase.