A new methodology for gray-scale character segmentation andrecognition

Generally speaking, through the binarization of gray-scale images, useful information for the segmentation of touched or overlapped characters may be lost in many cases. If we analyze gray-scale images, however, specific topographic features and the variation of intensities can be observed in the character boundaries. In this paper, we propose a new methodology for character segmentation and recognition which makes the best use of the characteristics of gray-scale images. In the proposed methodology, the character segmentation regions are determined by using projection profiles and topographic features extracted from the gray-scale images. Then a nonlinear character segmentation path in each character segmentation region is found by using multi-stage graph search algorithm. Finally, in order to confirm the nonlinear character segmentation paths and recognition results, a recognition-based segmentation method is adopted. Through the experiments with various kinds of printed documents, it is convinced that the proposed methodology is very effective for the segmentation and recognition of touched and overlapped characters     

基于笔划包围盒的脱机手写体汉字分割算法

汉字分割是脱机手写体汉字识别预处理的重要部分，改进了基于笔画包围盒的汉字分割算法。根据方向行程长度提取出汉字的笔画，对所得笔画建立包围盒。使用4种基本合并操作得到汉字的粗略的分割。最后使用动态规划的方法实现汉字的精细分割。实验结果表明，该算法较好地解决了汉字分割中的笔画粘连和重叠问题。     

带标记线的心脏核磁共振图象分析综述

多年来,对心脏核磁共振(MR)图象的分析研究一直是医学图象领域的一个重要课题,上世纪80年代末期出现的标记技术引起了医学图象界的重视,因为标记线的引入改变了传统的心脏左心室的运动跟踪方式,所以也使得对带标记线的心脏核磁共振图象分析成为当前医学图象领域的一个研究热点.为了使人们对带标记线的心脏核磁共振图象分析技术的现状有一个概略了解,首先简要介绍了标记线的运动跟踪原理;接着,详细介绍了对带标记线的心脏MR图象的分割技术,其中包括左心室内外轮廓的分割和标记线的跟踪;而在左心室的形状恢复和运动重建方面,则详细介绍了几种主要的方法,包括可形变模型、随机模型、B样条模型、调和相方法和光流方法,由于应变分析可为临床提供直观的量化信息,为此也讨论了相关的理论方法和重要成果;最后指出了现存技术中的几个问题,这对进一步的研究工作是有益的.     

Image data field for homogeneous region based segmentation

Some innovative methods for image segmentation inspired by physical world are presented in recent years. Aiming to find homogeneous regions and latent semantic information, the paper presents a novel image segmentation method based on image data field. Image data field, developed by simulating the short-range nuclear forces field theory in the physical world, can effectively represent the spatial interactions of neighborhood pixels. Then, the homogeneous regions are characterized by maximum tolerance classes, which induced by homogeneous attraction relation comparing the contributions of potential values in image data field. More specifically, the proposed method mainly focuses on the images with uneven lighting conditions. Compared with the existing relative methods on a variety of images, the experimental results suggest that the presented method is efficient and effective.     

图像分割算法研究综述

图像分割是图像处理中的一个经典难题,也是图像处理和计算机视觉领域中的基本技术。目前,广大研究者在图像分割领域里已提出了上百种分割方法,每种分割方法只局限特定的分割对象,至今没有一种通用的方法。本文综述了近年在图像分割技术上出现的常用图像分割算法以及它们的优缺点,展望了图像分割的前景和面临的挑战。     

Survey on liver CT image segmentation methods

The segmentation of liver using computed tomography (CT) data has gained a lot of importance in the medical image processing field. In this paper, we present a survey on liver segmentation methods and techniques using CT images, recent methods presented in the literature to obtain liver segmentation are viewed. Generally, liver segmentation methods are divided into two main classes, semi-automatic and fully automatic methods, under each of these two categories, several methods, approaches, related issues and problems will be defined and explained. The evaluation measurements and scoring for the liver segmentation are shown, followed by the comparative study for liver segmentation methods, pros and cons of methods will be accentuated carefully. In this paper, we concluded that automatic liver segmentation using CT images is still an open problem since various weaknesses and drawbacks of the proposed methods can still be addressed.     

Integrating multiple cues into adaptive hierarchical segmentation for high-resolution remote-sensing images

Image segmentation has been, and still is, a hot research topic in computer vision and pattern recognition. However, few existing segmentation algorithms are suitable for all objects presented in high-resolution remote-sensing (HRRS) images, because the relevant methods often implement segmentation in the same mode for the whole image rather than considering the different characteristics of various objects. Therefore, this article proposes an adaptive hierarchical segmentation framework for HRRS images by integrating multiple cues (e.g. intensity, texture and boundary). This two-stage framework first analyses the class of region presented in the study image, then according to this analysis, partitions each region class by adaptively utilizing the proper segmentation method with the most representative features. The distinctive characteristics of this framework are that the first stage simplifies the problem before using the segmentation method, and the second stage guarantees that the segmentation is carried out with the representative cues and corresponding suitable method for these cues. The performance of the proposed segmentation framework is demonstrated through a complete set of experimental results and substantiated using quantitative criteria.     

A novel multiresolution fuzzy segmentation method on MR image

Multiresolution-based magnetic resonance (MR) image segmentation has attracted attention for its ability to capture rich information across scales compared with the conventional segmentation methods. In this paper, a new scale-space-based segmentation model is presented,where both the intra-scale and inter-scale properties are considered and formulated as two fuzzy energy functions. Meanwhile, a control parameter is introduced to adjust the contribution of the similarity character across scales and the clustering character within the scale. By minimiT.ing thecombined inter/intra energy function, the multiresolution fuzzy segmentation algorithm is derived.Then the coarse to fine leading segmentation is performed automatically and iteratively on a set of multiresolution images. The validity of the proposed algorithm is demonstrated by the test image and pathological MR images. Experiments show that by this approach the segmentation results,especially in the tumor area delineation, are more precise than those of the conventional fuzzy segmentation methods.     

利用Hough变换和先验知识的车牌字符分割算法

随着科技的发展，车牌识别系统得到了很多应用。车牌识别系统包含三个部分：车牌定位、字符分割和字符识别。车牌字符分割是车牌自动识别系统中的重要步骤。车牌字符分割中存在噪声干扰、边框影响、铆钉和间隔符影响、车牌旋转、光照不均等问题。这些问题容易造成分割不准确，甚至分割错误。针对这些问题，该文提出了一种先分段，再利用Hough变换拟合直线的水平分割方法和基于先验知识约束的垂直分割方法，同时提出目标增强的预处理方法。大量实验表明，该算法较好地解决了以上问题，适用于各种质量的车牌图像，分割的准确率较高。     

Hidden Markov measure field models for image segmentation

Parametric image segmentation consists of finding a label field that defines a partition of an image into a set of nonoverlapping regions and the parameters of the models that describe the variation of some property within each region. A new Bayesian formulation for the solution of this problem is presented, based on the key idea of using a doubly stochastic prior model for the label field, which allows one to find exact optimal estimators for both this field and the model parameters by the minimization of a differentiable function. An efficient minimization algorithm and comparisons with existing methods on synthetic images are presented, as well as examples of realistic applications to the segmentation of Magnetic Resonance volumes and to motion segmentation.     

pSnakes: A new radial active contour model and its application in the segmentation of the left ventricle from echocardiographic images

Active contours are image segmentation methods that minimize the total energy of the contour to be segmented. Among the active contour methods, the radial methods have lower computational complexity and can be applied in real time. This work aims to present a new radial active contour technique, called pSnakes, using the 1D Hilbert transform as external energy. The pSnakes method is based on the fact that the beams in ultrasound equipment diverge from a single point of the probe, thus enabling the use of polar coordinates in the segmentation. The control points or nodes of the active contour are obtained in pairs and are called twin nodes. The internal energies as well as the external one, Hilbertian energy, are redefined. The results showed that pSnakes can be used in image segmentation of short-axis echocardiogram images and that they were effective in image segmentation of the left ventricle. The echo-cardiologist's golden standard showed that the pSnakes was the best method when compared with other methods. The main contributions of this work are the use of pSnakes and Hilbertian energy, as the external energy, in image segmentation. The Hilbertian energy is calculated by the 1D Hilbert transform. Compared with traditional methods, the pSnakes method is more suitable for ultrasound images because it is not affected by variations in image contrast, such as noise. The experimental results obtained by the left ventricle segmentation of echocardiographic images demonstrated the advantages of the proposed model. The results presented in this paper are justified due to an improved performance of the Hilbert energy in the presence of speckle noise.     

词典驱动的联机手写日文病名识别研究

研究了一种有效的词典驱动的联机手写日文病名识别方法。病名词典以树结构存储,包含21 713个病名短语。在切分中,手写病名字符串通过分析相邻笔划之间的空间信息等特征被切分为原始的片段序列。连续的片段动态地合并为候选字符模式,不同的合并方式产生不同的候选字符序列,这样可构成一个切分候选网格。在识别过程中,结合病名词典匹配来限制候选字符模式的类别扩展,采用集束搜索策略来寻找到一条最优路径作为识别结果。用500个实际的手写病名样本做实验,平均每个病名的识别时间为0.87 s,识别正确率为83.16%。     

Segment confidence-based binary segmentation (SCBS) for cursive handwritten words

A novel segment confidence-based binary segmentation (SCBS) for cursive handwritten words is presented in this paper. SCBS is a character segmentation strategy for off-line cursive handwriting recognition. Unlike the approaches in the literature, SCBS is an unordered segmentation approach. SCBS is repetition of binary segmentation and fusion of segment confidence. Each repetition generates only one final segmentation point. The binary segmentation module is a contour tracing algorithm to find a segmentation path to divide a segment into two segments. A set of segments before binary segmentation is called pre-segments, and a set of segments after binary segmentation is called post-segments. SCBS uses over-segmentation technique to generate suspicious segmentation points on pre-segments. On each suspicious segmentation point, binary segmentation is performed and the highest fusion value is recorded. If the highest fusion value is greater than the one of pre-segments, the suspicious segmentation point becomes the final segmentation point for the iteration. If not, no more segmentation is required. Segment confidence is obtained by fusing mean character, lexical and shape confidences. The proposed approach has been evaluated on local and benchmark (CEDAR) databases.     

古代汉字文献切分研究

针对古代汉字文档的特点,提出了适合于古文档的列切分方法和字切分方法。提出的列切分方法直接对文档的笔画投影进行分析,采用一种基于分层投影过滤和变长间隙阈值的递归切分算法。该算法在列间隔较小、列与格线存在粘连、文档具有一定程度的倾斜的情况下,也能准确地抽取出列,尤其对短列的切分达到了较好的效果。提出的字切分方法分为两步,进行粗切分确定大致的切分位置,采用基于连通域分析与粘连点判断的方法做进一步的细切分。该算法对具有较多粘连和重叠汉字的列,也能较好地切分出完整的单字。实验结果表明,提出的方法用于古代汉字文档切分能够获得较好的效果。     

Efficient character segmentation approach for machine-typed documents

In this paper an efficient approach for segmentation of the individual characters from scanned documents typed on old typewriters is proposed. The approach proposed in this paper is primarily intended for processing of machine-typed documents, but can be used for machine-printed documents as well. The proposed character segmentation approach uses the modified projection profiles technique which is based on using the sliding window for obtaining the information about the document image structure. This is followed by histogram processing in order to determine the spaces between lines, words and characters in the document image. The decision-making logic used in the process of character segmentation is describes and represents the most an integral aspect of the proposed technique. Beside the character segmentation approach, the ultra-fast architecture for geometrical image transformations, which is used for image rotation in the process of skew correction, is presented, and its fast implementation using pointer arithmetic and a highly optimized low-level machine routine is provided. The proposed character segmentation approach is semi-automatic and uses threshold values to control the segmentation process. Provided results for segmentation accuracy show that the proposed approach outperforms the state-of-the-art approaches in most cases. Also, the results from the aspect of the time complexity show that the new technique performs faster than state-of-the-art approaches and can process even very large document images in less than one second, which makes this approach suitable for real-time tasks. Finally, visual demonstration of the proposed approach performances is achieved using original documents authored by Nikola Tesla.     

中文信息检索引擎中的分词与检索技术

文中论述了在开发中文信息检索系统中所涉及到的两项关键技术，即中文分词技术和检索技术。针对中文分词技术，介绍了一种改进的正向最大匹配切分算法，以及为消除歧义引入的校正策略，并在此基础上结合统计方法处理未登录词。针对检索技术，综述了几种最常用的检索模型的原理，并对每种模型的优缺点进行了简要分析。最后对给出的分词算法进行了测试，测试结果表明该分词算法准确度和效率能够满足实用的要求。     

光谱比值在细胞多光谱图像分割中的应用

为了对细胞多光谱图像进行快速、准确的分割，首先探讨了光谱比值在细胞多光谱显微图像分割中的应用，然后提出了利用多光谱图像的光谱信息，并结合传统分割方法的一种新的细胞自动分割方法。该方法首先通过从扣除背底后的多光谱图像中选择两个波段图像进行光谱比值操作来生成一幅比率图像，然后对该图像进行自动多阈值分割、二值形态学操作，最终获得了细胞的胞浆和胞核覆盖层。该方法首次将光谱比值技术应用到细胞多光谱显微图像分割中，对骨髓细胞图像的自动分割实验表明，该方法具有分割准确、分割速度快、受外界干扰少的特点，该方法也可以推广到其他多光谱显微图像的分割中。     

Two-stage segmentation of unconstrained handwritten Chinese characters

Correct segmentation of handwritten Chinese characters is crucial to their successful recognition. However, due to many difficulties involved, little work has been reported in this area. In this paper, a two-stage approach is presented to segment unconstrained handwritten Chinese characters. A handwritten Chinese character string is first coarsely segmented according to the background skeleton and vertical projection after a proper image preprocessing. With several geometric features, all possible segmentation paths are evaluated by using the fuzzy decision rules learned from examples. As a result, unsuitable segmentation paths are discarded. In the fine segmentation stage that follows, the strokes that may contain segmentation points are first identified. The feature points are then extracted from candidate strokes and taken as segmentation point candidates through each of which a segmentation path may be formed. The geometric features similar to the coarse segmentation stage are used and corresponding fuzzy decision rules are generated to evaluate fine segmentation paths. Experimental results on 1000 Chinese character strings from postal mail show that our approach can achieve a reasonable good overall accuracy in segmenting unconstrained handwritten Chinese characters.