Off-Line Character Recognition Using HMM by Multiple Directional Feature Extraction and Voting with Bagging Algorithm

  • Authors:
  • Hiromitsu Nishimura;Makoto Kobayashi;Minoru Maruyama;Yasuaki Nakano

  • Affiliations:
  • -;-;-;-

  • Venue:
  • ICDAR '99 Proceedings of the Fifth International Conference on Document Analysis and Recognition
  • Year:
  • 1999

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Abstract

The purpose of our research is to improve the recognition rate of off-line character recognition systems using the HMM (Hidden Markov Model) without increasing a number of HMM parameters too much. Some 2-dimensional HMM character recognition systems have been proposed to increase representational power. However, since 2-D HMM has much more complex structure and thus requires much more parameters than 1-dimensional HMM, it becomes very hard to gather sufficient samples in order to guarantee the successful generalization. To overcome the problem, we propose a method for character recognition using 1-D HMMs in multiple directions with 2-dimensional feature extraction. To further improve the performance, bagging algorithm is also exploited. The voting by the bagging algorithm, which is reported effective in some neural-network and decision tree classifier systems, has never been used in HMM character recognition systems yet. In our experiment, the recognition rate is increased by about 1% with the multiple directional HMM character recognition system compared to the 1-D HMM character recognition system. The recognition rate is further increased by about 1% with the HMM character recognition system using bagging algorithm.