Patent GB-1440517-A (GB)
Title: Character-identification device
IPC: G06K9/68
Filed: 1973-06-19
Abstract: 1440517 Character recognition systems SOC HONEYWELL BULL 19 June 1973 [30 June 1972] 29111/73 Heading G4R The system attempts to identify an unknown character by inspection of preselected regions of it. The inspection reveals whether the character is more likely to be akin to one reference character n than to each of one or more other reference characters i, j .... If this is the case, a further inspection of other regions takes place to identify the character certainly as n. The electrical image of the character is held in a store (10, Fig. 2, not shown) which feeds N identification circuits. Each circuit identifies one of N characters and comprises up to N-1 discrimination circuits. Fig. 4 shows one identification circuit n and two (i, j) of the discrimination circuits in it. Each discrimination circuit comprises two operators P1, P2 and an OR gate L. The operators are fed from the store (via connections, not shown) with digital signals representing regions of the image. The operator P1(i)n provides an output at 22 if the state of the regions shows that the unknown character is more likely to be a character i than n, and an output at 23 if more likely to be n than i. If each of the discrimination circuits i, j . . . either opts in favour of n, or does not opt for any character, gate M1 provides an output to a corresponding stage 17 of a first register (11) and to AND gate M2. Each discrimination circuit provides an input to gate M2 if P1 has opted for n or if P2 decides n is present. The output of gate M2 passes to a corresponding stage 18 of a second register (12). By examination of the stages of the registers the character is identified or rejected. For example, if only one stage of the first register (11) is set the character is identified as the corresponding reference character. If not stage is set a rejection is signalled. However if more than one stage is set the stages of the second register (12) are examined. If only one is set this identifies the character. If none or more than one is set a rejection is signalled. In a modification of Fig. 4 (Fig. 5, not shown) each n output of the operators P1 of an identification circuit n is connected to a unit (32) which enables gate M1 only if more than a given number of the operators have opted for n. Thus a character can be identified as n only if less than a certain number of operators P1 have been unable to exercise an option, i.e. find the character ambiguous. In a further modification (Fig. 6, not shown) the first register (11), comprised of stages 17, is omitted. Fig. 9b shows a circuit defining an operator P1(2)0 for distinguishing between numerals 2 and 0 in OCRA form. The regions inspected are C, D and E, Fig. 9a. Signals representing the state of the regions are summed at 34. The signals from a region, e.g. C, and C1, C2. If the region is wholly black C1=C2=1, if partly black C1#C2, and if white C1=C2=0. The sum S is compared with thresholds #1, #2. If S<2 the operator indicates the character is more likely to be 2 than 0: if S #4 the character is more likely to be 0. The operator P2 is defined by a circuit (e.g. as in Fig. 11d, 11h, not shown) which distinguishes one character from another by, for example, inspecting several elongated regions which fall within or without the character boundary, depending on the character, as described with reference to Fig. 11 (not shown). The regions selected for P1 and P2 may be adjacent the normal ends of character strokes.