A Compact On-line and Off-line Combined Recognizer

This paper describes a compact on-line/off-line combined handwriting recognizer for Japanese characters. Conventional combined recognizers mainly consider the recognition accuracy, though recognition speed and memory size are important as well. Especially, the off-line method requires a large prototype dictionary, and therefore the on-line/off-line combined recognizers are difficult to use practically in a small computer. In order to tackle this problem, we propose an on-line/offline combined recognizer where an off-line recognizer is composed of the Modified Quadratic Discriminant Function whose dictionary size is significantly reduced. Moreover, its on-line recognizer is composed of a structured character pattern representation (SCPR) dictionary which reduces the total size of memory and Linear-time Elastic Matching (LTM) which reduces the computation time. Experimental results show that the cumulative recognition rate of top 5 candidates of a proposed 1MB dictionary is 97.3% (almost the same as that of a conventional 90MB dictionary) and that the recognition speed of the 1MB dictionary is 1.75 times faster then that of the 90MB dictionary.

[1]  A. Tanaka,et al.  Online recognition of freely handwritten Japanese characters using directional feature densities , 1992, Proceedings., 11th IAPR International Conference on Pattern Recognition. Vol.II. Conference B: Pattern Recognition Methodology and Systems.

[2]  Fumitaka Kimura,et al.  Modified Quadratic Discriminant Functions and the Application to Chinese Character Recognition , 1987, IEEE Transactions on Pattern Analysis and Machine Intelligence.

[3]  Sargur N. Srihari,et al.  Decision Combination in Multiple Classifier Systems , 1994, IEEE Trans. Pattern Anal. Mach. Intell..

[4]  Jiri Matas,et al.  On Combining Classifiers , 1998, IEEE Trans. Pattern Anal. Mach. Intell..

[5]  Yoav Freund,et al.  A decision-theoretic generalization of on-line learning and an application to boosting , 1997, EuroCOLT.

[6]  Kazuhiko Yamamoto,et al.  On-line Handwriting Character Recognition using Directional Features and Direction-Change Features , 1999 .

[7]  Masaki Nakagawa,et al.  A Model of On-line Handwritten Japanese Text Recognition Free from Line Direction and Writing Format Constraints , 2005, IEICE Trans. Inf. Syst..

[8]  Masaki Nakagawa,et al.  'Online recognition of Chinese characters: the state-of-the-art , 2004, IEEE Transactions on Pattern Analysis and Machine Intelligence.

[9]  Jin Hyung Kim,et al.  A probabilistic framework for combining multiple classifiers at abstract level , 1997, Proceedings of the Fourth International Conference on Document Analysis and Recognition.

[10]  Tin Kam Ho,et al.  The Random Subspace Method for Constructing Decision Forests , 1998, IEEE Trans. Pattern Anal. Mach. Intell..

[11]  K. Yamada,et al.  On-line Japanese character recognition experiments by an off-line method based on normalization-cooperated feature extraction , 1993, Proceedings of 2nd International Conference on Document Analysis and Recognition (ICDAR '93).

[12]  Leo Breiman,et al.  Bagging Predictors , 1996, Machine Learning.

[13]  Masaki Nakagawa,et al.  Collection of on-line handwritten Japanese character pattern databases and their analyses , 2004, Document Analysis and Recognition.

[14]  E. Mandler,et al.  Combining the Classification Results of Independent Classifiers Based on the Dempster/Shafer Theory of Evidence , 1988 .

[15]  K. Ishigaki,et al.  Hybrid pen-input character recognition system based on integration of online-offline recognition , 1999, Proceedings of the Fifth International Conference on Document Analysis and Recognition. ICDAR '99 (Cat. No.PR00318).

[16]  Ching Y. Suen,et al.  A Method of Combining Multiple Experts for the Recognition of Unconstrained Handwritten Numerals , 1995, IEEE Trans. Pattern Anal. Mach. Intell..

[17]  Masaki Nakagawa,et al.  A new warping technique for normalizing likelihood of multiple classifiers and its effectiveness in combined on-line/off-line japanese character recognition , 2002, Proceedings Eighth International Workshop on Frontiers in Handwriting Recognition.