Character recognition system utilizing feature extraction

Claim 1

A character recognition system comprising means for scanning fields on a document, a video shift register having a plurality of stages for serially storing and shifting a binary quantization of a character pattern sampled within said field on said document and a mask matrix comprising a plurality of gates each connected to a different combination of said video shift register stages wherein the improvement comprises connecting said gates only to selected ones of said video shift register stages which correspond to an area of said document field, said gates being enabled continuously to sense predetermined binary combinations in said video shift register as said binary quantization is shifted through said video shift register, feature extraction logic comprising a plurality of feature detectors each of which is connected to a different combination of said mask matrix gates, timing means connected to said feature detectors to enable each detector only during a predetermined time interval related to the location of the feature associated with the respective feature detector within a character, said timing means enabling said features to be detected by said feature detectors only during the time interval in which the respective feature passes through said selected ones of said video shift register stages, and a vertical data column, said data column comprising a recirculating shift register having a plurality of stages equal in number to the number of samples taken in the vertical column within a field, said video shift register and said recirculating shift register each being responsive to shift pulses provided at the same rate, input means for the recirculating shift register being responsive to the signals of one stage of said video shift register so that as said character pattern passes through said one stage of said shift register, the vertical profile of said character pattern is inserted in said recirculating shift register, means responsive to signals from said recirculating register for determining the position of said character within a scanned field, said scanning means responsive to signals from said position determining means so that the position of said scanning means is moved if said character is not in a preferred position of said field.