MACHINE RECOGNITION OF PATTERNS

摘要

1523272 Character recognition NATIONAL RESEARCH DEVELOPMENT CORP 4 June 1975 [5 June 1974] 24973/74 Heading G4R To determine whether a pattern such as a handwritten character corresponds to one of a predetermined set of reference characters the reference characters are each divided into a notional grid and a binary matrix is produced and stored for each reference character to indicate the presence or absence of a mark in respective locations or cells of the grid. A similar matrix is produced for the pattern. To allow the grid to be fairly coarse a given cell s hj in the pattern is compared with a corresponding cell t hj in each reference character and with the eight cells surrounding t hj and a given cell t hj in each reference character is compared with the corresponding cell s hj in the pattern and with the eight cells surrounding s hj . To implement the comparison sets Qgh, are defined, where g is a superscript and each Q hJ four pairs of cells and has s hj in each pair and t hj and three of the other eight cells surrounding t hj , e.g. Qg44 might contain cell pairs (s 44 , t 44 ), (s 44, t 54 ), (s 44 , t 43 ), (s 44 , t 53 ). A similar set is defined in which t hj is paired with s hj and three of the eight cells around s hj . As a consequence g has eight values g‹ to g7. Fixed pairs of cells q8 are examined each of which contain a mark and which contain s hj and a respective one of the eight cells surrounding t hj . A set E is defined which contains all pairs cells q both of which contain a mark. The cells are examined and if they don't correspond are eliminated from E. If a pair of cells correspond, e.g. qn then only pairs of cells q that are situated in the corresponding Q, e.g. Qn are examined. Variables Yg are defined as Y g = 1 if no pair qg are eliminated from E; Y g = 0 otherwise. A similar procedure is performed for cells t hj and sets P hjg which correspond to Q hjg . Quantities z8 and yg are determined whic are 1 if a particular set Qg contains at least one pair q in E. For a given unknown pattern the following procedure is carried out for each specimen pattern. Initially each Y0 ... Y7 is set equal to 1. For each g=0,..., 7 Yg is set equal to zero if This is repeated for each g = 0,.. 7 until no y g is set equal to zero. The unknown pattern is asssigned to the class of the specimen pattern for which the process ends with at least one of y 1 , . . ., y 7 equal to 1 when # has a minimum value.