A proposal for analogue cum digital character recognition

An analogue-digital device for the recognition of hand printed capital block letters and numerals is proposed. The unknown characters are projected onto a grid of photo­ diodes. The edges and corners of the character are then emphasized by a detail filter and the output voltages of the diodes are normalized. Each of the 36 characters is placed in one of four subsets to reduce the number of samples required for identification. Then the characters are examined for the presence or absence of eighteen characteristics. Up to this stage the operation has been analogue in nature but since a large memory capacity is required the operation is transferred to an on-line digital computer. The computer operates on the above information. The analogue signals are quantized and codes for each character are established during the learning phase of the computer programme. During the testing or identification stage the computer programme employs three criteria to identify the unknown presented on the grid.of photo-diodes.