Off-line handwritten Korean character recognition based on stroke extraction and representation

In this paper, we propose an off-line recognition method for handwritten Korean characters based on stroke extraction and representation. To recognize handwritten Korean characters, it is required to extract strokes and stroke sequence to describe an input of two-dimensional character as one-dimensional representation. We define 28 primitive strokes to represent characters and introduce 300 stroke separation rules to extract proper strokes from Korean characters. To find a stroke sequence, we use stroke code and stroke relationship between consecutive strokes. The input characters are recognized by using character recognition trees. The proposed method has been tested for the most frequently used 1000 characters by 400 different writers and showed recognition rate of 94.3%.     

在线草图识别中用户手绘习惯建模方法

手绘草图是概念设计和思路外化的一种高效的表达方式。用户绘制草图时存在的多种形式，及其随意性和模糊性使得用户适应性问题逐渐成为草图识别的核心课题。本文提出了一种在线草图识别的用户建模方法来捕捉绘制草图时的用户习惯，主要包括两个方面的内容：一是基于SVM的主动式增量学习方法，二是基于动态用户建模的手绘复杂图形的识别方法。前者与传统的增量式学习方法相比，在识别精度相同的情况下所需的训练时间和训练数据集要少得多。后者则是基于笔划信息以及笔划间的顺序和空间关系信息，采用增量式决策树捕捉用户的输入习惯和过程信息。实验证明了本文方法在在线草图识别中的有效性和高效性。     

一种无笔序手写体汉字在线识别方法

文中介绍了一种无笑序手写汉字在线识别方法，提出了基于汉字笔画数的编码方法。整个识别过程为两大部分，首先进行笔画分类，然后根据笔画序列码和汉字的结构完成入手 写何不在于识别。由于本系统要求可以无笔序地进行汉字输入，给汉分类带的来很大的困难，为此，在汉字结构匹配时，提出了一种结构特征搜索及排索算法，很好地解决了要求无笔序输入所带来的问题，实践证明，这种方法用于无笔序手汉字的在线识别是非常有效的。     

Model-based stroke extraction and matching for handwritten Chinese character recognition

This paper proposes a model-based structural matching method for handwritten Chinese character recognition (HCCR). This method is able to obtain reliable stroke correspondence and enable structural interpretation. In the model base, the reference character of each category is described in an attributed relational graph (ARG). The input character is described with feature points and line segments. The strokes and inter-stroke relations of input character are not determined until being matched with a reference character. The structural matching is accomplished in two stages: candidate stroke extraction and consistent matching. All candidate input strokes to match the reference strokes are extracted by line following and then the consistent matching is achieved by heuristic search. Some structural post-processing operations are applied to improve the stroke correspondence. Recognition experiments were implemented on an image database collected in KAIST, and promising results have been achieved.     

在线草图识别中的用户适应性研究

提出一种在线草图识别用户适应性解决方法，该方法分别采用支撑向量机主动式增量学习和动态用户建模技术进行笔划和复杂图形的识别．支撑向量机主动式增量学习方法通过主动“分析”用户增量数据，并根据用户反馈从中选择重要数据作为训练样本，可有效地鉴别用户手绘笔划特征，快速地识别用户输入笔划．动态用户建模技术则采用增量决策树记录草图的笔划构成及其手绘过程，有效捕捉用户的复杂图形手绘习惯，进而利用模糊匹配在草图绘制过程中预测和识别复杂图形．实验表明：该方法具有很好的效果，为解决在线草图识别及其用户适应性问题提供参考．     

计算机实时手写中文自动识别

本文介绍用于联机手写中文字自动识别的新方法与新算法.由于下述各点的实现,手写 文字时可以减少许多限制,增加书写自由.①笔划的抽取经由两次分段实现:首先连续采样, 将输入笔划变换成线段组成,再对线段的长度进行比较,删去相对不重要的成份.②用笔划校 正技术将不应分离的笔划重新组合成规范笔划,或者将不应联写的复合笔划重新分解成基本 笔划.③用非完全匹配技术使失真字可以识别.④用混序笔划重排算法可使一个混序笔划输 入的字重新排列笔顺.⑤笔划位置和长度作为进一步特征,可区别模糊字.     

Analysis of stroke structures of handwritten Chinese characters

Most handwritten Chinese character recognition systems suffer from the variations in geometrical features for different writing styles. The stroke structures of different styles have proved to be more consistent than geometrical features. In an on-line recognition system, the stroke structure can be obtained according to the sequences of writing via a pen-based input device such as a tablet. But in an off-line recognition system, the input characters are scanned optically and saved as raster images, so the stroke structure information is not available. In this paper, we propose a method to extract strokes from an off-line handwritten Chinese character. We have developed four new techniques: 1) a new thinning algorithm based on Euclidean distance transformation and gradient oriented tracing, 2) a new line approximation method based on curvature segmentation, 3) artifact removal strategies based on geometrical analysis, and 4) stroke segmentation rules based on splitting, merging and directional analysis. Using these techniques, we can extract and trace the strokes in an off-line handwritten Chinese character accurately and efficiently.     

Improving mixture of experts for view-independent face recognition using teacher-directed learning

In this paper we develop a new learning method, called teacher-directed learning (TDL), for mixture of experts (ME) to perform view-independent face recognition. In the basic form of ME the problem space is automatically divided into several subspaces for the experts, and the outputs of experts are combined by a gating network. In our proposed method, the ME is directed to adapt to a particular partitioning corresponding to predetermined views. To do this, we apply a new learning method to ME, called TDL, in a way that according to the pose of the input training sample, only the weights of the corresponding experts are updated. We apply TDL to MEs, composed of MLP experts and a radial basis function gating network, with different representation schemes: global, single-view and overlapping eigenspace. We test them with previously intermediate unseen views of faces. The experimental results support our claim that directing the experts to a predetermined partitioning of the face space improves the performance of the conventional ME for view-independent face recognition. Comparison with some of the most related methods indicates that the proposed model yields excellent recognition rate in view-independent face recognition.     

Statistical character structure modeling and its application to handwritten Chinese character recognition

This paper proposes a statistical character structure modeling method. It represents each stroke by the distribution of the feature points. The character structure is represented by the joint distribution of the component strokes. In the proposed model, the stroke relationship is effectively reflected by the statistical dependency. It can represent all kinds of stroke relationship effectively in a systematic way. Based on the character representation, a stroke neighbor selection method is also proposed. It measures the importance of a stroke relationship by the mutual information among the strokes. With such a measure, the important neighbor relationships are selected by the nth order probability approximation method. The neighbor selection algorithm reduces the complexity significantly because we can reflect only some important relationships instead of all existing relationships. The proposed character modeling method was applied to a handwritten Chinese character recognition system. Applying a model-driven stroke extraction algorithm that cooperates with a selective matching algorithm, the proposed system is better than conventional structural recognition systems in analyzing degraded images. The effectiveness of the proposed methods was visualized by the experiments. The proposed method successfully detected and reflected the stroke relationships that seemed intuitively important. The overall recognition rate was 98.45 percent, which confirms the effectiveness of the proposed methods.     

基于增量学习支持向量机的音频例子识别与检索

音频例子识别与检索的主要任务是构造一个良好的分类学习机，而在构造过程中，从含有冗余样本的训练库中选择最佳训练例子、节省学习机的训练时间是构造分类机面临的一个挑战，尤其是对含有大样本训练库音频例子的识别．由于支持向量是支持向量机中的关键例子，提出了增量学习支持向量机训练算法．在这个算法中，训练样本被分成训练子库按批次进行训练，每次训练中，只保留支持向量，去除非支持向量．与普通和减量支持向量机对比的实验表明，算法在显著减少训练时间前提下，取得了良好的识别检索正确率．     

Teacher-directed learning in view-independent face recognition with mixture of experts using overlapping eigenspaces

A model for view-independent face recognition, based on Mixture of Experts, ME, is presented. In the basic form of ME the problem space is automatically divided into several subspaces for the experts, and the outputs of experts are combined by a gating network. In our proposed model, the ME is directed to adapt to a particular partitioning corresponding to predetermined views. To force an expert towards a particular partitioning corresponding to predetermined views, a new representation scheme, overlapping eigenspaces, is introduced, that provides each expert with an eigenspace computed from the faces in the corresponding neighboring views. Furthermore, we use teacher-directed learning, TDL, in a way that according to the pose of the input training sample, only the weights of the corresponding experts are updated. The experimental results support our claim that directing the experts to a predetermined partitioning of the face space improves the performance of the conventional ME for view-independent face recognition. Comparison with some of the most related methods indicates that the proposed model yields excellent recognition rate in view-independent face recognition.     

基于参照模型的联机手写汉字笔划提取及识别

本文提出一种基于参照模型的联机手写汉字的笔划提取及识别的新方法 ,在该方法中不但考虑了流字识别中笔划的提取、匹配 ,还充分考虑到笔划间的连接关系 ,在手写汉字识别中取得了较好的效果。     

New grouping and fitting methods for interactive overtraced sketches

This paper describes a new method for recognizing overtraced strokes to 2D geometric primitives, which are further interpreted as 2D line drawings. This method can support rapid grouping and fitting of overtraced polylines or conic curves based on the classified characteristics of each stroke during its preprocessing stage. The orientation and its endpoints of a classified stroke are used in the stroke grouping process. The grouped strokes are then fitted with 2D geometry. This method can deal with overtraced sketch strokes in both solid and dash linestyles, fit grouped polylines as a whole polyline and simply fit conic strokes without computing the direction of a stroke. It avoids losing joint information due to segmentation of a polyline into line-segments. The proposed method has been tested with our freehand sketch recognition system (FSR), which is robust and easier to use by removing some limitations embedded with most existing sketching systems which only accept non-overtraced stroke drawing. The test results showed that the proposed method can support freehand sketching based conceptual design with no limitations on drawing sequence, directions and overtraced cases while achieving a satisfactory interpretation rate.     

Online recognition of handwritten music symbols

In this paper, we propose an effective online method to recognize handwritten music symbols. Based on the fact that most music symbols can be regarded as combinations of several basic strokes, the proposed method first classifies all the strokes comprising an input symbol and then recognizes the symbol based on the results of stroke classification. For stroke classification, we propose to use three types of features, which are the size information, the histogram of directional movement angles, and the histogram of undirected movement angles. When combining classified strokes into a music symbol, we utilize their sizes and spatial relation together with their combination. The proposed method is evaluated using two datasets including HOMUS, one of the largest music symbol datasets. As a result, it achieves a significant improvements of about 10% in recognition rates compared to the state-of-the-art method for the datasets. This shows the superiority of the proposed method in online handwritten music symbol recognition.     

The complete analysis of the discrete time finite DBMAP/G/1/N queue

A comprehensive analysis of the DBMAP/G/1/N queueing system for both the “arrival first” and “departure first” policies is given including detailed proofs and latest results on an algorithmic recipe to compute the z-transform of the waiting time probability function as well as the probability function itself. Additionally, expressions for the probability of simultaneous arrivals and departures and an algorithm to compute them are presented for the first time. The framework presented allows dealing with a superposition DMAP+DBMAP as an input process. For both streams in the superposition, per stream waiting time probability functions are given for the case of a deterministic service time, which is relevant for the modeling of ATM networking (both wired and wireless). Together with findings for the continuous time case, this paper completes the insights into finite queueing systems of the M/G/1-type. In comparison with the method of the unfinished work, which can be used to analyze finite queueing systems with deterministic service-time only and, besides other semi-Markovian input processes, with the DBMAP as an input, the M/G/1-paradigm provides much faster algorithms to compute loss probabilities and waiting time moments, due to the smaller system matrix. Note that the D[B]MAP has proved a versatile stochastic process, which can also be tuned to represent periodic correlation functions and not only geometrically decaying ones.     

On-line handwritten Chinese character recognition via a fuzzy attribute representation

Chinese characters are constructed by strokes according to structural rules. Therefore, the geometric configurations of characters are important features for character recognition. In handwritten characters, stroke shapes and their spatial relations may vary to some extent. The attribute value of a structural identification is then a fuzzy quantity rather than a binary quantity. Recognizing these facts, we propose a fuzzy attribute representation (FAR) to describe the structural features of handwritten Chinese characters for an on-line Chinese character recognition (OLCCR) system. With a FAR. a fuzzy attribute graph for each handwritten character is created, and the character recognition process is thus transformed into a simple graph matching problem. This character representation and our proposed recognition method allow us to relax the constraints on stroke order and stroke connection. The graph model provides a generalized character representation that can easily incorporate newly added characters into an OLCCR system with an automatic learning capability. The fuzzy representation can describe the degree of structural deformation in handwritten characters. The character matching algorithm is designed to tolerate structural deformations to some extent. Therefore, even input characters with deformations can be recognized correctly once the reference dictionary of the recognition system has been trained using a few representative learning samples. Experimental results are provided to show the effectiveness of the proposed method.     

An approach for real-time recognition of online Chinese handwritten sentences

With the advances of handwriting capturing devices and computing power of mobile computers, pen-based Chinese text input is moving from character-based input to sentence-based input. This paper proposes a real-time recognition approach for sentence-based input of Chinese handwriting. The main feature of the approach is a dynamically maintained segmentation–recognition candidate lattice that integrates multiple contexts including character classification, linguistic context and geometric context. Whenever a new stroke is produced, dynamic text line segmentation and character over-segmentation are performed to locate the position of the stroke in text lines and update the primitive segment sequence of the page. Candidate characters are then generated and recognized to assign candidate classes, and linguistic context and geometric context involving the newly generated candidate characters are computed. The candidate lattice is updated while the writing process continues. When the pen lift time exceeds a threshold, the system searches the candidate lattice for the result of sentence recognition. Since the computation of multiple contexts consumes the majority of computing and is performed during writing process, the recognition result is obtained immediately after the writing of a sentence is finished. Experiments on a large database CASIA-OLHWDB of unconstrained online Chinese handwriting demonstrate the robustness and effectiveness of the proposed approach.     

基于连笔消除的空间手写字符识别方法

信息的连续采集会造成部分字符存在连笔,进而影响字符识别率.为此,提出一种基于连笔消除的空间手写字符识别方法.将空间手写字符平面化,提取字符拐点和笔画方向特征.为避免笔画的误消除,利用支持向量机把未知字符分为带连笔字符和非连笔字符,通过连笔的书写特征消除连笔,将空间字符轨迹转化为平面字符轨迹,直接用平面字符分类器进行字符识别.实验结果表明,该方法连笔消除效果显著,利用现有字符库即可获得较高的字符识别率.     

脱机手写汉字识别的最优采样特征新方法

在脱机手写汉字识别中，笔画形变是造成识别率下降的主要原因，减少笔画形变的影响是提高脱机手写汉字识别率的关键。针对上述问题，提出了最优采样特征。该特征以目前被广泛应用的方向线素特征为基础，在一定的约束条件下，通过移动采样点的位置，可以适应笔画的形变。从而减少特征的类内方差，提高特征的可分性，改进了识别性能。通过在THCHR样本集上进行实验，并对最优采样特征和方向线素特征的实验结果进行比较，验证了最优采样特征的识别率优于方向线索特征。