指纹识别技术的研究与分析

本文详细介绍了指纹识别技术的原理、指纹识别中的图像采集、图像预处理、特征提取与特征匹配四个过程。指纹识别的关键技术是对指纹的特征提取与特征匹配,论文中详细分析了图像预处理的过程及特征点提取的各种方法,最后对各种指纹特征匹配算法的优缺点进行了分析与比较。     

角点检测技术综述

角点是图像很重要的特征,对图像图形的理解和分析有很重要的作用。对灰度图像、二值图像、边缘轮廓曲线的角点检测算法进行综述,分析了相关的算法,并对各种检测算法给出了评价。     

几种特征提取算法性能的评估

特征提取与匹配是图像识别、目标跟踪等计算机视觉问题的基础和关键。研究了不同的点特征提取算法性能。现有的评估方法大多是从速度、灵敏度等几个角度来评价算法的性能。现提供一个新的标准,以获得不同的特征提取算法在不同图像类型中的预期水平。主要研究包括：FAST、SIFT、PCA-SIFT、SURF 和 ORB特征提取算法。以算法提取到的正确匹配特征点对的数目作为主要评价标准,通过实验测试各种算法在不同类型的图像中的性能,总结出算法最适合应用的环境。     

SAR图像线特征提取方法的仿真

雷达图像的线条特征提取算法一般分为三步:首先作图像预处理,然后采用特定的边缘检测算子提取边缘点,最后形成各种有意义的线条特征。本文采用两步检测算子来直接检测边缘点,不需要对图像进行预处理。首先用比率线探测器对SAR图像进行线特征的提取,然后用互相关探测器进行提取,最后融合二者的结果。本文对该算法进行仿真,证实了该算法能够很好的提取图像的线特征。     

基于贡献矩阵的微钙化点检测

提出了基于贡献矩阵的特征提取方法。首先采用基于结构分析的统计方法构造贡献矩阵,利用贡献矩阵对图像预处理;通过二维主成分分析方法提取图像特征。将此算法用于微钙化点图像特征提取,利用支持向量机分类器进行分类。实验结果表明,该算法加快了训练速度,同时有效地降低了微钙化点检测的假阳性。     

一种高效的基于局部特征的显著区域检测算法

图像特征提取是图像/视频检索问题的关键。研究人员发现,假如对整张图像或视频帧做特征提取,会产生大量的特征信息,从而影响图像/视频帧的匹配时间。由于人们通常只对图像中部分关键的区域感兴趣,因此在对图像做局部特征提取时可以先对图像进行显著区域检测,排除非关键区域上的特征信息,从而减低匹配所需的特征点数,提高匹配的处理速度。但是由于传统的显著区域检测算法计算复杂,会对图像特征提取过程产生额外的时间开销。提出一种快速的显著区域检测算法,根据局部特征提取算法特征检测阶段得到的特征点分布,利用最大子矩阵和算法,在损失较小的准确度的情况下快速检测出图像的显著区。     

直方图均衡化与SURF重构的图像特征提取方法

针对SURF算法提取图像特征点较少的问题,提出了一种经直方图均衡化处理,重构SURF尺度空间（R-SURF）的图像特征提取方法。该方法能提高图像特征点检测数目,同时保持较高的匹配率,并且继承SURF算法的良好特性。将算法与SURF和C-SURF算法进行比较实验,结果表明R-SURF具有更好的特征检测能力。     

改进的Canny算子与SIFT算法相结合的医学图像特征提取

微创外科手术中的图像特征快速提取与分析,可以使计算机具备图像实时识别的能力,提高手术的成功率。对常用的边缘与角点特征进行了分析,提出了边缘与角点相结合的特征提取方法。以二尖瓣索修复微创手术图像为例,对常用的几种边缘算法和改进的Canny算法进行了分析比较,利用改进的Canny算子所得到的较为完整的检测边缘信息,运用SIFT算法提取图像角点,剔除了一些伪特征点,得到了图像匹配时所需要的更加精确的信息。为后续的图像融合与复原以及三维图像重建打下了良好的基础。     

基于线段融合的空间非合作目标稳健特征提取算法

相对位姿测量是空间非合作目标态势感知的主要内容,在位姿测量中,需要先对目标图像进行特征提取,而特征提取的精度和鲁棒性直接影响位姿测量性能。为了提高空间非合作目标特征提取的鲁棒性,本文给出一种基于线段融合的特征提取算法。该算法首先采用基于梯度的滤波器来消除空间目标图像的背景干扰,然后采用LSD直线检测算法、Hough Lines直线检测算法和Shi-Tomasi角点检测算法提取三组特征点,再用K-D空间划分树以及K最近邻搜索算法融合这三组特征点,保留包含显著特征的较少数量特征点,进一步组合成线段结构,并对线段进行融合,以此来提取反映目标整体几何框架的信息,从而提升稳健性。仿真实验和半物理仿真实验测试结果表明,本文提出的基于线段融合的特征提取方法在空间目标特征提取中具有更好的稳健性。     

特征提取算法在工件识别中的研究

特征提取在工件识别中具有重要的意义. 运用灰度变换与平滑去噪对获取到的原始图像进行图像预处理. 提出改进的工件特征提取方法. SURF算法作为SIFT算法的加速版,不仅能够确保检测到的特征点的稳定性,而且能很大程度地加快特征提取的时间,满足了工件识别过程中实时性的需求. 采用改进的SURF算法的特征匹配方法进行工件的识别. 实验表明,改进的特征匹配方法对工件识别精确且速度较快.     

高光谱图像压缩质量评价技术研究进展

众所周知,数据量的庞大,致使高光谱图像数据的应用受到很大限制。这种庞大的数据量对于许多情况,尤其对于卫星数据链路,由于受带宽和星上存储能力的局限,致使不能实时进行数据传输,因此必须使用有损压缩方式来减小高光谱图像的数据量。但由于有损压缩带来的信息丢失,对高光谱数据的不同后续应用影响不同,因此压缩图像的质量评价技术得到了广泛重视。为使人们对这一质量评价技术有一定了解,首先对高光谱图像压缩方法进行简单介绍;然后对现存的客观失真参数评价、应用算法统计结果评价、相似敏感度标准抽取评价等主要的压缩质量评价技术进行综述,同时比较它们的优缺点,并在此基础上,提出了一种基于最优性能的质量评估框架;最后对该技术今后的研究发展进行了展望。     

非刚性三维模型检索特征提取技术研究

三维模型特征描述符是一种简洁且信息量丰富的表示方式.特征提取是许多三维模型分析处理任务的关键步骤.近年来,针对非刚性三维模型特征提取技术的研究引起了人们的广泛关注.本文首先汇总了常用的非刚性三维模型基准数据集和算法评价标准.然后在广泛调研大量文献和最新成果的基础上,将非刚性三维模型特征分为人工设计的特征描述符和基于学习的特征描述符两大类并分别加以介绍.对每类方法所包含的典型算法,尤其是最近几年基于深度学习的特征提取算法的基本思想、优缺点进行了分析、对比和总结.最后进行总结,并对未来可能的发展趋势加以展望.     

A generalisation of model selection criteria

In this article we generalise some of the existing model selection criteria used in statistics and computer vision. Model selection criteria are mostly used to decide which model is more appropriate for explaining a specific data set. We adapt these criteria in a way that they can be used for the evaluation of models fitted to different data sets and for the evaluation of sets of models. We found this adaption especially useful in situations where we have a set of models with domains that may overlap and where we need to find an optimal subset of models for explaining the whole data set. Adapted model selection criteria were then succesfully used in range image segmentation application (reverse engineering), based on the recover-and-select paradigm.     

A new mathematical model and a Lagrangean decomposition for the point-feature cartographic label placement problem

This paper proposes a 0-1 integer linear programming model for the point-feature cartographic label placement problem based on labeling of the largest number of free labels. In addition, one non-trivial valid inequality is presented to strengthen this proposed model. Even with the strengthened model, a commercial solver was not able to solve a representative sample of known instances presented in the literature. Thus, we also present a Lagrangean decomposition technique based on graph partitioning. Our added approaches established optimal solutions for practically all the used instances and the results significantly improved the ones presented in recent studies concerning the problem.     

一种基于点特征的异源SAR图像配准方法

适配性分析是合成孔径雷达(Synthetic aperture radar, SAR)图像匹配的重要研究内容, 它研究图像是否适合选作基准图的问题. 本文研究基于点特征配准方法的异源SAR图像适配性分析, 以特征点的数目及稳健程度来度量SAR图像适配性, 提出基于点特征的异源图像适配性评价算法, 并构建出一种评价特征点稳定性的准则, 以指导选取合适的退化模型.实验结果表明本文所提出的点特征适配性评价机制能有效地度量指定SAR图像的适配性, 从而近似得出保障图源的适配性排序结果.     

Automated text-based analysis for decision-making research

We present results from a study on constructing and evaluating a support tool for the extraction of patterns in distributed decision -making processes, based on design criteria elicited from a study on the work process involved in studying such decision-making. Specifically, we devised and evaluated an analysis tool for C² researchers who study simulated decision-making scenarios for command teams. The analysis tool used text clustering as an underlying pattern extraction technique and was evaluated together with C² researchers in a workshop to establish whether the design criteria were valid and the approach taken with the analysis tool was sound. Design criteria elicited from an earlier study with researchers (open-endedness and transparency) were highly consistent with the results from the workshop. Specifically, evaluation results indicate that successful deployment of advanced analysis tools requires that tools can treat multiple data sources and offer rich opportunities for manipulation and interaction (open-endedness) and careful design of visual presentations and explanations of the techniques used (transparency). Finally, the results point to the high relevance and promise of using text clustering as a support for analysis of C² data.     

一种基于相似性的规则集一致性度量的新方法

规则学习算法通过学习样本产生规则集,如何判断规则集的好坏?目前规则集的评估标准有很多,如一致性、可测量性和易理解性评估,但它们有各自的缺点。提出一种新的评估规则集方法:相似性度量。这种度量方法可以计算出两个规则集之间的正相似性与负相似性。实验说明这种新的度量方法可以被用来评估规则集间的一致性,并且可以决定使用哪种算法解决某类问题或选择组合分类模型中的基模型。     

Heuristics for cartographic label placement problems

The cartographic label placement problem is an important task in automated cartography and Geographical Information Systems. Positioning the texts requires that overlap among texts should be avoided, that cartographic conventions and preference should be obeyed. This paper examines the point-feature cartographic label placement problem (PFCLP) as an optimization problem. We formulate the PFCLP considering the minimization of existing overlaps and labeling of all points on a map. This objective improves legibility when all points must be placed even if overlaps are inevitable. A new mathematical formulation of binary integer linear programming that allows labeling of all points is presented, followed by some Lagrangean relaxation heuristics. The computational tests considered instances proposed in the literature up to 1000 points, and the relaxations provided good lower and upper bounds.     

A Survey of Web Information Extraction Systems

The Internet presents a huge amount of useful information which is usually formatted for its users, which makes it difficult to extract relevant data from various sources. Therefore, the availability of robust, flexible Information Extraction (IE) systems that transform the Web pages into program-friendly structures such as a relational database will become a great necessity. Although many approaches for data extraction from Web pages have been developed, there has been limited effort to compare such tools. Unfortunately, in only a few cases can the results generated by distinct tools be directly compared since the addressed extraction tasks are different. This paper surveys the major Web data extraction approaches and compares them in three dimensions: the task domain, the automation degree, and the techniques used. The criteria of the first dimension explain why an IE system fails to handle some Web sites of particular structures. The criteria of the second dimension classify IE systems based on the techniques used. The criteria of the third dimension measure the degree of automation for IE systems. We believe these criteria provide qualitatively measures to evaluate various IE approaches.     

Signal extraction and knowledge discovery based on statistical modeling

In the coming post IT era, the problems of signal extraction and knowledge discovery from huge data sets will become very important. For these problems, the use of good model is crucial and thus the statistical modeling will play an important role. In this paper, we show two basic tools for statistical modeling, namely the information criteria for the evaluation of the statistical models and generic state-space model which provides us with a very flexible tool for modeling complex and time-varying systems. As examples of these methods we shall show some applications in seismology and macro economics.