JPS634230B

PURPOSE:To enable highly accurate correlation, to cope with irregular local variation of hand written letters etc. and to read complicated letter patterns by correlating characteristics extracted from an input pattern successively from general to details. CONSTITUTION:The directional property of a line is extracted by a preparation section A from an object input pattern is accordance with information of a point and points around it. Using the extracted directional property pattern, higher order characteristics by directional projection of large area and lower order characteristics by derectional projection of smaller area are extracted by a characteristic extraction section B. Further, matching between input pattern and mask for conception to be classified is made by a matching section C. The degree of matching is measured by correlation of higher order characteristics using the higher order characteristics provided beforehand and input pattern. Then, characteristic point is shifted in accordance with the result of correlation in higher order, and correlation and valuation of lower order characteristics are made. Thus, irregular letter patterns are read correctly.