CHARACTER RECOGNITION SYSTEMS

摘要

1383061 Character recognition systems SIEMENS AG 27 Sept 1972 [27 Sept 1971] 44643/72 Heading G4R A character recognition system which is insensitive to off-centring comprises a preprocessor in which image points in the scanned field are processed in parallel to provide a translationinvariant classification matrix. In one embodiment, illustrated by Fig. 4 which shows a simplified form of such a system using only 3 Î 3 image points, the outputs of the rows of 3 scanning photodetectors PD are connected as indicated to respective groups of 3 units SG. Each unit comprises an operational amplifier arranged to generate a required one of a number of Walsh functions, i.e. each generates an output which is formed by summing some of the 3 inputs and subtracting the others. The outputs represent a first transformation of the image matrix. The output from each unit in each row is connected to a respective second group of 3 units SG as shown, to provide a second 3 Î 3 transformed image matrix. The signals of this matrix pass to a resistor unit KP which feeds an arrangement of diodes DS providing a 2 x 2 matrix which is translationinvariant and is used in known manner to identify the character according to its significance probability. In another embodiment (Fig. 5, not shown), in which the outputs of each row of photodetectors PD are passed in turn to a store, the elements in the store store values representing Walsh functions, the elements being controlled by shift registers generating the appropriate add and subtract signals according to the row selected. The resulting signals undergo a second transformation to provide the 3 x 3 transformed image matrix from which the 2 x 2 matrix is derived as in the first embodiment.