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Now showing 1 - 10 of 26

A language model based on semantically clustered words in a Chinese character recognition system
(1997-08-01)
Lee, HJ
;
Tung, CH
;
資訊工程學系
;
Department of Computer Science
This paper presents a new method for clustering the words in a dictionary into ward groups. A Chinese character recognition system can then use these groups in a language model to improve the recognition accuracy. In the language model, the number of parameters we must train beforehand can be kept to a reasonable value. The Chinese synonym dictionary Tong2yi4ci2 ci2lin2 providing the semantic features is used to calculate the weights of the semantic attributes of the character-based word classes. The weights of the semantic attributes are next updated according to the words of the Behavior dictionary, which has a rather complete word set. Then, the word classes are clustered to In groups according to the semantic measurement by a greedy method. The words in the Behavior dictionary can finally be assigned to the m groups. The parameter space for the bigram contextual information of the character recognition system is m(2). From the experimental results, the recognition system with the proposed model has shown better performance than that of a character-based bigram language model. (C) 1997 Pattern Recognition Society. Published by Elsevier Science Ltd.
Typeface identification for printed Chinese characters
(1998-03-01)
Tseng, YH
;
Kuo, CC
;
Lee, HJ
;
資訊工程學系
;
Department of Computer Science
In this paper, we propose a methodology for identifying typefaces of printed Chinese characters in documents. Three kinds of features, stroke width means, stroke width variations, and aspect ratio, are first used to classify character typefaces as: Black, Li, Kai-Round, or Ming-Song. Each of the last two groups contains two typefaces. Vertical/horizontal stroke width ratios are used to distinguish between the Ming and Song typefaces and accumulative pixel ratio to distinguish between the Kai and Round typefaces. Six different typeface feature distributions measured from 5401 printed Chinese characters are considered, and a trapezoid-shaped membership function is constructed for each distribution. Based on these membership functions, we determine what typeface each input character belongs to using a two-level decision tree. To increase the identification rate, the typeface of a certain character is adjusted according to the typeface identification results of the front and the next characters. In the character recognition system, we use two statistical features: crossing counts and contour directional counts. We achieved an 89.87% typeface identification rate in our experiments, and a 95.60% character recognition rate.
An efficient algorithm for form structure extraction using strip projection
(1998-09-01)
Chen, JL
;
Lee, HJ
;
資訊工程學系
;
Department of Computer Science
This paper presents an efficient strip-projection-based approach to extracting form structures from form documents for office automation. To locate the data, we have to extract and interpret the form structure. In this paper, a strip projection method is presented for extracting the form structure. We first segment input form images into uniform vertical and horizontal strips. Since most form lines are vertical or horizontal, we project the image of each vertical strip horizontally and that of each horizontal strip vertically. The peak positions in these projection profiles denote possible locations of lines in form images. We then extract the lines starting with the possible line positions in the source image. After all lines have been extracted, redundant lines are removed using a line-verification algorithm and broken lines are linked using a line-merging algorithm. Experimental results show that the proposed method can extract form structures from A4-sized documents in about 3 seconds which is very efficient, compared with the methods based on Hough transformation and run-based line-detection algorithms. (C) 1998 Pattern Recognition Society. Published by Elsevier Science Ltd. All rights reserved.
Speeding up Chinese character recognition in an automatic document reading system
(1998-11-01)
Tseng, YH
;
Kuo, CC
;
Lee, HJ
;
資訊工程學系
;
Department of Computer Science
In this paper, we present two techniques for speeding up character recognition. Our character recognition system, including the candidate-cluster selection and modified branch-and-bound detail-matching modules, is implemented using two statistical features: crossing-counts and contour-direction counts. In the training stage, we divide characters into different clusters by using reference characters. To have a very high recognition rate, the candidate-cluster selection module selects the top 60 clusters with minimal distances from among 300 predefined clusters. To further speed-up the recognition speed, we use a modified branch-and-bound algorithm in the detail-matching module. In the automatic document reading system, characters and punctuation marks are first extracted from printed document images and sorted according to their positions and the document orientation. The system then recognizes all printed Chinese characters between pairs of punctuation marks. The results are then spoken aloud by a speech-synthesis system. The character recognition system and the text-to-speech synthesis system are integrated in the Windows-based document reading system, which provides a user-friendly environment. (C) 1998 Pattern Recognition Society. Published by Elsevier Science Ltd. All rights reserved.
Chinese handwritten character segmentation in form documents
(1999)
Chen, JL
;
Wu, CH
;
Lee, HJ
;
資訊工程學系
;
Department of Computer Science
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 small blocks 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 characters are tested during our experiments, the correct segmentation rates of 92.34% and 91.76% are obtained with and without the OCR module.
Recognition-based handwritten Chinese character segmentation using a probabilistic Viterbi algorithm
(1999-08-01)
Tseng, YH
;
Lee, HJ
;
資訊工程學系
;
Department of Computer Science
This paper presents a recognition-based character segmentation method for handwritten Chinese characters. Possible non-linear segmentation paths are initially located using a probabilistic Viterbi algorithm. Candidate segmentation paths are determined by verifying overlapping paths, between-character gaps, and adjacent-path distances. A segmentation graph is then constructed using candidate paths to represent nodes and two nodes with appropriate distances are connected by an are. The cost in each are is a function of character recognition distances, squareness of characters and internal gaps in characters. After the shortest path is detected from the segmentation graph, the nodes in the path represent optimal segmentation paths. In addition, 125 text-line images are collected from seven form documents. Cumulatively, these text-lines contain 1132 handwritten Chinese characters. The average segmentation rate in our experiments is 95.58%. Moreover, the probabilistic Viterbi algorithm is modified slightly to extract text-lines from document pages by obtaining non-linear paths while gaps between text-lines are not obvious. This algorithm can also be modified to segment characters from printed text-line images by adjusting parameters used to represent costs of arcs in the segmentation graph. (C) 1999 Elsevier Science B.V. All rights reserved.
Scalable rate control for MPEG-4 video
(2000-09-01)
Lee, HJ
;
Chiang, T
;
Zhang, YQ
;
交大名義發表
;
National Chiao Tung University
This paper presents a scalable rate control (SRC) scheme based on a more accurate second-order rate-distortion model. A sliding-window method for data selection is used to mitigate the impact of a scene change. The data points for updating a model are adaptively selected such that the statistical behavior is improved. For video object (VO) shape coding, we use an adaptive threshold method to remove shape-coding artifacts for MPEC-4 applications. A dynamic bit allocation among VOs is implemented according to the coding complexities for each VO, SRC achieves more accurate bit allocation with low latency and limited buffer size. In a single framework, SRC offers multiple layers of controls for objects, frames, and macroblocks (MBs), At MB level, SRC provides finer bit rate and buffer control. At multiple VO level, SRC offers superior VO presentation for multimedia applications. The proposed SRC scheme has been adopted as part of the International Standard of the emerging ISO MPEG-I standard [1], [2].
On end-to-end architecture for transporting MPEG-4 video over the Internet
(2000-09-01)
Wu, DP
;
Hou, YWT
;
Zhu, WW
;
Lee, HJ
;
Chiang, TH
With the success of the Internet and flexibility of MPEG-4, transporting MPEG-4 video over the Internet is expected to be an important component of many multimedia applications in the near future. Video applications typically have delay and loss requirements, which cannot be adequately supported by the current Internet, Thus, it is a challenging problem to design an efficient MPEG-4 video delivery system that can maximize the perceptual quality while achieving high resource utilization. This paper addresses this problem by presenting an end-to-end architecture for transporting MPEG-4 video over the Internet, We present a framework for transporting MPEG-4 video, which includes source rate adaptation, packetization, feedback control, and error control. The main contributions of this paper are: 1) a feedback control algorithm based on Real Time Protocol (RTP) and Real Time Control Protocol (RTCP); 2) an adaptive source-encoding algorithm for MPEG-4 video which is able to adjust the output rate of MPEG-4 video to the desired rate; and 3) an efficient and robust packetization algorithm for MPEG video bit-streams at the sync layer for Internet transport. Simulation results show that our end-to-end transport architecture achieves good perceptual picture quality for MPEG-4 video under low bit-rate and varying network conditions and efficiently utilizes network resources.
Field data extraction for form document processing using a gravitation-based algorithm
(2001-09-01)
Chen, JL
;
Lee, HJ
;
資訊工程學系
;
Department of Computer Science
This paper presents a novel approach to grouping Chinese handwritten field data filled in form documents using a gravitation-based algorithm. An algorithm is developed to extract handwritten field data which may be written out of form fields. First, form lines are extracted and removed from input form images. Connected-components are then detected from remaining data, and the gravitation for each connected-component is computed by using the black pixel counts as their mass. Next, we move connected-components according to their gravitation. As generally known, filled-in data have the locality property, i.e., data of the same field are normally written in a local area consecutively. Therefore, the relationship of these connected-components can be determined by this property. Repeatedly moving these connected-components according to their neighbor components allows us to determine which connected-components should be extracted for a particular field. Experimental results demonstrate the effectiveness of the proposed method in grouping field data, (C) 2001 Pattern Recognition Society. Published by Elsevier Science Ltd. All rights reserved.
X-ray reflectivity and FTIR measurements of N-2 plasma effects on the density profile of hydrogen silsesquioxane thin films
(2001-10-01)
Lee, HJ
;
Lin, EK
;
Wu, WL
;
Fanconi, BM
;
Lan, JK
The density depth profile and chemical bond structure of hydrogen silsesquioxane (HSQ) thin films treated with an N-2 plasma with varying power and exposure time were measured using specular X-ray reflectivity (SXR) and Fourier transform infrared (FTIR) spectroscopy. The SXR data indicated that the density profile of an untreated HSQ film is not uniform. At least four layers with different electron densities were required to fit the SXR data. For HSQ films treated with either increasing plasma power or plasma exposure time, the film roughness increased and a densified layer was observed at the film/air interface. The thickness of the densified layer increased with both plasma power and plasma exposure time. In the FTIR spectra of the plasma-treated films, the intensities of the Si-O peaks due to the network structure and the Si-OH peak due to water absorption increased and the intensities of the Si-H peaks decreased. The FTIR data show that the plasma converts the HSQ structure into a SiO2-like structure and are consistent with the densification observed in the SXR measurements. In general, the HSQ film is more sensitive to increasing plasma power than to increasing plasma exposure time. (C) 2001 The Electrochemical Society.

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