Feature dimensionality reduction for the verification of handwritten numerals

A novel method based on multi-modal discriminant analysis is proposed to reduce feature dimensionality. First, each class is divided into several clusters by the k-means algorithm. The optimal discriminant analysis is implemented by multi-modal mapping. Our method utilizes only those training samples on and near the effective decision boundary to generate a between-class scatter matrix, which requires less CPU time than other nonparametric discriminant analysis (NDA) approaches [Fukunaga and Mantock in IEEE Trans PAMI 5(6):671–677, 1983; Bressan and Vitria in Pattern Recognit Lett 24(5):2473–2749, 2003]. In addition, no prior assumptions about class and cluster densities are needed. In order to achieve a high verification performance of confusing handwritten numeral pairs, a hybrid feature extraction scheme is developed, which consists of a set of gradient-based wavelet features and a set of geometric features. Our proposed dimensionality reduction algorithm is used to congregate features, and it outperforms the principal component analysis (PCA) and other NDA approaches. Experiments proved that our proposed method could achieve a high feature compression performance without sacrificing its discriminant ability for classification. As a result, this new method can reduce artificial neural network (ANN) training complexity and make the ANN classifier more reliable.