PRELIMINARY PROCESSING OF CHARACTERS IN RECOGNITION SYSTEMS

Abstract : Several methods proposed by various authors for correcting distortions in typed characters are briefly reviewed. It is noted that typed characters differ primarily because of distortions caused by the composition of typewriter ribbon and paper, the ink color, and the presence of carbon paper. Consequently, the 'actual' character outlines (on the paper) differ considerably from the 'ideal' character and the reliability of their recognition by man or machine is reduced. In one of the schemes for correcting character distortion, for example, preliminary character processing at the recognition unit input i.e., quantization of the input signal at two or more levels with subsequent logical processing is proposed. In another scheme, the inclusion of the smoothing process into a character recognition algorithm is proposed. A three-dimensional-filtration method is described in greater detail. The essence of this method lies in the use, during the character-scanning process, of values of contrast function, not only from the scanning line but also from adjacent regions.