Copyright © 2004 Elsevier Ltd. All rights reserved.
Off-line isolated handwritten Thai OCR using island-based projection with n-gram model and hidden Markov models*1
Available online 15 June 2004.
Abstract
Many traditional works on off-line Thai handwritten character recognition used a set of local features including circles, concavity, endpoints and lines to recognize hand-printed characters. However, in natural handwriting, these local features are often missing due to rough or quick writing, resulting in dramatic reduction of recognition accuracy. Instead of using such local features, this paper presents a method called multi-directional island-based projection to extract global features from handwritten characters. As the recognition model, two statistical approaches, namely interpolated n-gram model (n-gram) and hidden Markov model (HMM), are proposed. The experimental results indicate that the proposed scheme achieves high accuracy in the recognition of naturally-written Thai characters with numerous variations, compared to some common previous feature extraction techniques. Another experiment with English characters also displays quite promising results.
Author Keywords: Thai character recognition; Island-based projection; n-gram model; Hidden Markov models
Article Outline
- 1. Introduction
- 2. Previous feature extraction methods
- 3. Multi-directional island-based projection
- 4. n-gram and HMM for character recognition
- 4.1. Basic formulation of character recognition problem
- 4.2. Statistical approach
- 4.3. n-gram models for character recognition
- 4.4. HMMs for character recognition
- 5. The recognition scheme
- 6. Experimental results
- 6.1. Data set & model parameters
- 6.2. Basic experiments
- 6.3. Comparison to other feature extraction methods
- 6.4. Effect of the number of clusters and states
- 7. Summary and result analysis
- 8. Conclusion and future works
- Appendix A. Discussion materials
- References






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