METHOD AND APPARATUS FOR RECOGNISING HANDWRITTEN CHARACTERS IN AN OPTICAL CHARACTER RECOGNITION MACHINE

摘要

1454813 Character recognition systems OPTICAL BUSINESS MACHINES Inc 6 Feb 1974 [25 July 1973] 05535/74 Heading G4R An array of binary signals representing a scanned character in a field is normalized by combining bits in pairs of rows and columns to produce a normalized array of bits representing a reduced size character. The pairs are selected in accordance with the degree of reduction necessary, as determined by the height and width of the character. Signals representing a scanned field containing a handwritten character are stored as an array of bits in 32 columns of 64-bit shift registers. Circuitry determines the position, height and width of the character by developing signals corresponding to the horizontal and vertical projections of the character as the signals are written serially into the registers. For example when a series of 64 bits, corresponding to a vertical slice of the field, contains one or more black (character-portion) bits a 1-bit is set in a width shift register. If the register contains 5 or more consecutive black bits to the right of a white bit the left hand edge of the character is assumed to have just entered the store. The position of the right hand edge of the character, as indicated by the right hand end of the series of black bits, indicates the character width and is used to select the degree of reduction needed. As indicated in Fig. 67, if the character is 15 bits wide no reduction is needed. If it is 19 bits wide a 5 : 4 reduction is needed and is obtained by combining the bits in corresponding rows of columns 4, 5; 9,10; 14, 15; 18, 19 of the store. Similar combination takes place for other reduction ratios. In a generally similar manner _the height of the character is obtained. To ensure that voids or specks do not adversely effect the height determination the determination is inhibited until 5 successive columns con- .taining blacks have been detected and is maintained until 2 successive columns containing no blacks have been detected. The pairs of rows to be combined to reduce the character height are as indicated in Fig. 68. The signals representing the character thus normalized are stored in 15 columns of 24-bit registers. In addition the normalized character is shifted right to centralize it in the normalized store. Electronic masking is used to detect 7 line features of the character. One such mask is 15 bits wide by 4 bits high. If a black bit occurs in any of the four mask rows and across 8 consecutive columns the presence of a horizontal line is indicated. The mask is scanned vertically down the store character to detect such a line in the top, middle, and bottom regions of the store. Other masks, each comprising a number of sub-masks (Figs. 39-66, not shown) detect lines in the upper and lower left and right portions of the store. The 7-bit signal from the masks passes to recognition circuitry comprising gates which detect particular combinations of mask outputs to identify the character or to indicate an error in the case of unresolvable ambiguity. The recognition circuitry provides a signal on one of a number of leads corresponding to the various characters which can be recognized and feeds a coding unit which provides a corresponding parallel-bit signal to a utilization device.