Quantitative Evaluation of Print Quality for Optical Character Recognition Systems

Objective, mechanical, and quantitative evaluation of printed characters is discussed. Print quality can be quantified by the peak value of the print contrast signal (PCS), the average stroke width, the noise factor, and the centroid deviation. An instrument for evaluating a large number of printed characters has been constructed. This instrument consists of a scanner, a minicomputer, and its peripherals. Strains imposed on the scanned data are corrected by using the characteristics of the scanner. Two types of documents are processed by the instrument, and results of evaluation are compared with the performance of an optical character recognition (OCR) system. Experimental results clarify that the proposed evaluation method of print quality can be applied in practice. Also described are a quantitative expression of print quality for a set of input characters and the feasibility of an absolute determination of print quality.