GB1423010A - Character recognition apparatus - Google Patents

Abstract

1423010 Character recognition systems INTERNATIONAL BUSINESS MACHINES CORP 2 May 1973 [9 May 1972] 20958/73 Heading G4R A character recognition apparatus includes means for performing a sequence of tests upon the character to be identified. Each test for a feature of the character depends upon the presence or absence of the feature tested for by the preceding test. The test sequence thus takes the form of a decision tree. The apparatus disclosed may use a column of photo-sensors moved over the character or a single cell which receives light from successively illuminated parts of the character. The signals are digitized and passed to a shift register storage matrix. As the character steps through the matrix signals from a square array of the image points are fed from the matrix to a store and may be used for removal of spurii. The store can hold at least two charaictets. The matrix store also passes the character signals to circuitry which determines the horizontal and vertical extent and position of the character. The information is used to centre a notional grid on the character, and the series of tests is performed with reference to the grid points. The tests determine character features such as the directions of stroke elements, and the presence of bays. The decision tree identifies a character by performing only the tests necessary for the relevant features, e.g. as shown in Fig. 6, for the identification of a numeral 4. The succession of tests is controlled by a set of instructions held in a store. Each instruction for a current test includes the addresses of two more instructions. One or other of these addresses, dependent on the result of the current test operation, is used to obtain the next instruction, and so on.