Chinese Handwritten Character Segmentation in Form Documents

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1 Chinese andwritten Character Segmentation in Form Documents Jiun-Lin Chen, Chi-ong Wu and si-jian Lee Department of Computer Science and Information Engineering National Chiao Tung University, sinchu, Taiwan Abstract. This paper presents a projection based method for segmenting handwritten Chinese characters in form documents with known structures. In the preprocessing phase, a noise removal method is proposed that preserves stroke connections and character edge points. In the character segmentation phase, the projection profile analysis method is used to segment a text line image into projection blocks. In addition, projection blocks are classified into one of four types: mark, half-word, single -word, and two -word. Large blocks are then split and smallblocks are merged. In addition, an OCR system is adopted to eliminate errors resulting from the inappropriate merging of Chinese numerical characters with other characters. As for 1319 Chinese charactersaretestedduring our experiments,the correct segmentation rates of 92.34% and 91.76% are obtained with and without the OCR module. Keywords:Noise removal,projectionprofile analysis,formdocumentprocessing, Character segmentation, Optical character recognition. 1. Introduction Organizations receive many form documents daily, and processing these form documents requires much human effort. Automatic form document processing systems can reduce the human effort involved and increase efficiency. A typical automatic document processing system typically consists of six modules: preprocessing, document layout analysis, character segmentation, feature extraction, character recognition, and content understanding [5]. Character segmentation has long been a critical topic in document analysis. The performance of a character segmentation process significantly affects recognition results of an OCR (optical character recognition system. A typical form document normally consists of three components: form frames, label fields, and data fields. In this paper, we present a projection based character segmentation algorithm for extracting handwritten characters from input form data fields. The form structures are assumed here to be known, i.e., form frames and label fields with printed characters have been extracted. Although many systems have been proposed for recognizing printed documents [1] [2] [3] [4], only a few were designed for recognizing handwritten documents. The difficulties of the segmentation of handwritten Chinese characters include the following: (1 skewed and curved text lines, (2 different sizes of characters mixed in a text line, and (3 ill-separated characters. Figure 1 presents several examples which are difficult for character segment. S.-W. Lee and Y. Nakano (Ed.: DAS'98, LNCS 1655, pp , Springer-Verlag Berlin eidelberg 1999

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15 362 Jiun-Lin Chen et al. References [1] Srihari, S.N., "Document Image Understanding," Proc. IEEE Computer Society Fall Joint Computer Conf., pp.87-96, [2] Wang, D. and S.N. Srihari, "Analysis of Form Images," Proc. 1st Internat. Conf. Document Anal. Recognition, pp , [3] Casey, R.G., D.R. Ferguson, K. Mohiuddin and E. Walach, "Intelligent forms processing system," Machine Vision and Applications, Vol. 5, pp , [4] Lam, S.W., L. Javanbakht, and S.N. Srihari, "Anatomy of a form reader," Proc. 2nd Intern. Conf. on Document Analysis and Recognition, pp , [5] L.A. Fletcher and R. Kasturi, "A robust algorithm for text string separation from mixed text/graphic images," IEEE Transactions on Pattern Analysis and Machine Intelligence, Vol. 10, No. 6, pp , [6] R.G. Casey and E. Lecolinet, "Survey of methods and strategies in character segmentation," IEEE Transaction on Pattern Analysis and Machine Intelligence, Vol. 18, No. 7, pp , July [7] Y. Lu, "Machine printed character segmentation - An overview," Pattern Recognition, Vol. 28, No. 1, pp , [8] G. Seni and E. Cohen, "External word segmentation of off-line handwritten text lines," Pattern Recognition, Vol. 27, No. 1, pp , [9] C.C. Chiang and S. S. Yu, "An iterative character segmentation method for irregularly formatted Chinese documents," in Proceedings of the 5th Optical Character Recognition and Document Analysis, Chung Li, Taiwan, 1996, pp [10] E. Lecolinet and J. V. Moreau, "A new system for automatic segmentation and recognition of unconstrained zip codes," in Proceedings Sixth Scandinavian Conference Image Analysis, Oulu, Finland, June 1989, pp [11] Y. Lu and M. Shridhar, "Character segmentation in handwritten words - An overview," Pattern Recognition, Vol. 29, No. 1, 1996, pp [12] W. Niblack, An Introduction to Digital Image Processing, Prentice all, [13] J. L. Chen and. J. Lee, "An efficient algorithm for Form Structure Extraction using Strip Projection," Pattern Recognition, Vol. 31, No. 9, pp , 1998.

Recognition-based Segmentation of Nom Characters from Body Text Regions of Stele Images Using Area Voronoi Diagram

Author manuscript, published in "International Conference on Computer Analysis of Images and Patterns - CAIP'2009 5702 (2009) 205-212" DOI : 10.1007/978-3-642-03767-2 Recognition-based Segmentation of