A handwritten Chinese character recognition system.pdf

? .Pattern Recognition Letters 19 1998 595–604 A handwritten Chinese character recognition system using hierarchical displacement extraction based on directional features Y. Mizukami Faculty of Engineering, Yamaguchi Uni?ersity, 2557 Tokiwadai, Ube, Yamaguchi 755, Japan Received 20 August 1997; revised 20 February 1998 Abstract A recognition system using displacement extraction based on directional features is proposed for handwritten Chinese characters. In the system, after extracting the features from an input image, the displacement is extracted by the minimization of an energy functional, which consists of the Euclidean distance and the smoothness of the extracted displacement. The coarse-to-fine strategy is adopted to escape local minima and reduce computational costs. The statistical classification is performed based on the estimated variance. In addition, the smoothness of the extracted displacement is utilized. An improvement in recognition performance is achieved as compared with the method without displacement extraction. q 1998 Elsevier Science B.V. All rights reserved. Keywords: Handwritten Chinese character recognition; Displacement extraction; Coarse-to-fine strategy; Directional feature; Statistical classification 1. Introduction The recognition of handwritten Chinese characters ?has been studied by many researchers e.g., Hilde- ? ..brandt and Liu 1993 . However, it is still one of the difficult pattern recognition problems because of the complex character shapes and the large number of categories as compared with the Roman alphabet. The shape variation of handwritten characters causes the misclassification, therefore the extraction problem of the displacement presented in an input pattern is important for the correct recognition. How- ever we should note that the problem of displace- ment extraction is ill-posed, since the solution is not unique. In the field of computer vision, various early vision problems, which are essentially ill-posed, have bee