Structural feature extraction on multiple bases with application to handwritten character recognition systems

H. Nishida and S. Mori (1992) proposed a clear, rigorous, and powerful method for the structural description of character shapes in terms of quasi-topological features (convexity and concavity), directional features, and singular points (branch points and crossings). Shapes are described by few components with rich features and shape prototypes (structural models) can be constructed automatically from the training data. However, the number of directions is fixed to 4, and more directions such as 8 or 16 cannot be dealt with. For various applications of Nishida and Mori´s method, the author presents a method for structural analysis and description of simple arcs or closed curves based on 2^m (m = 2,3,4,...) directional features and convex/concave features. Software OCR systems without specialized hardware have attracted much attention recently. Based on the method of structural analysis and description, the author describes a software implementation of a handwritten character recognition system with a multi-stage strategy