【作者】 陈桂友；

【导师】 孙同景；

【作者基本信息】 山东大学 ， 控制理论与控制工程， 2005， 博士

【摘要】 随着社会和经济的发展,人们对身份鉴别的准确性、安全性与实用性提出了更高的要求。基于信物或口令的传统身份鉴别方式存在容易丢失、遗忘、被复制及盗用的隐患。通过辨识人的生理和行为特征进行身份认证的生物识别技术提供了一个方便可靠的解决方案。生物识别技术以生物特征为基础,以信息处理技术为手段,将生物技术和信息技术有机结合在一起。在众多的生物识别技术中,指纹识别技术以方便易用、高准确率和低成本等诸多优势备受关注,已经成为身份认证的最有效手段,在电子商务、犯罪识别、信息安全等领域得到广泛的应用。指纹是手指末端正面皮肤上凸凹不平的纹路。在人的生长早期形成后,终生保持不变。自动指纹识别系统是集光电技术、图像处理、计算机及网络、数据库技术、模式识别技术等于一体的综合性系统,一般包括指纹图像采集、指纹图像处理、特征提取、特征值的比对与匹配等过程。针对自动指纹识别系统的运行过程,在总结该领域现有研究成果的基础上,本文对自动指纹识别系统中的关键算法进行了研究,在指纹图像评测、增强、指纹分类、指纹识别等方面,提出了行之有效的解决算法,并将指纹识别技术成功地应用到养老金发放在线指纹识别系统中。本文的主要工作如下:1.首先对生物识别系统的基本概念以及常见的生物识别技术进行了较为详细的综述,并对不同种类的生物识别技术进行比较;阐述了自动指纹识别系统的结构、工作原理和目前的研究现状。在分析自动指纹识别系统的关键问题基础上,提出了论文的研究内容。2.研究指纹图像的预处理过程,包括指纹图像的综合评测、指纹图像的增强、二值化、细化和修复问题。指纹图像评测方面,在研究现有指纹图像评测方法的基础上,提出了一种实用的指纹图像综合评测方法。对指纹登记过程和识别过程分别采取不同的指纹图像质量评测策略。在指纹登更多还原

【Abstract】 Accurate, secure and practical personal identification methods are highly required with the development of the social and economy. The traditional personal identification methods based on token or password have the hidden troubles. The token or password is prone to being lost, forgotten, copied and stolen. The traditional personal identification methods cannot satisfy the security requirement of our highly interconnected information society. Biometrics based on the physiological or behavior traits identification provides a convenient and reliable scheme. Among the numerous biometrics, more attentions have been paid to the fingerprint identification technology due to its convenience, high accuracy and low cost. The technique of fingerprint identification has become one of the widest used biometric identification techniques. It has been widely used in electronic commerce, criminal identification, information safety etc.Fingerprints are scraggly lines on the tip of fingers, which are invariable in one’s whole life after they formed in the early times of a person’s life. The automatic fingerprint identification system (AFIS) is a synthetical system that integrates photoelectric technique, image process, computer and network, database technique and pattern identification technique. It commonly includes fingerprint image collection, fingerprint image process, minutiae extraction, minutiae matching etc. Aimed at the running process of the AFIS, some key algorithms used in AFIS are studied in this paper based on summarizing existed research results. The paper presents effective algorithms in the aspects of the synthesis evaluation and enhancement of fingerprint image, fingerprint classification, fingerprint identification, etc. The AFIS designed in this paper has been used in the on-line identification system of retirement pension payoff successfully.The main points are as follows:(1) The basic concept of the biometric identification system and thefamiliar biometric identification techniques are summarized. The structure, principle and the research status quo of AFIS are introduced. The key problems in AFIS are analyzed.(2) The preprocessing of fingerprint images is studied, which includes the synthesis evaluation of image, fingerprint enhancement, binarization, thinning and repair. Based on the study of existed image evaluation methods, a practical synthesis evaluation method of fingerprint image is proposed. Different evaluation strategies are applied in fingerprint registration and identification process. Rough evaluation and fine evaluation are used in registration process in order to ensure the reliability of fingerprint template, and rough evaluation is adopted in identification process. In the process of fingerprint image enhancement, the fingerprint image enhancement algorithm based on adaptive filter and fingerprint image enhancement algorithm based on the curvelet transform are presented in order to improve the definition of fingerprint ridges and eliminate the noises effectively. Compare of different algorithms is carried out. An expert-experience-based fingerprint image repair algorithm is presented in order to eliminate the burrs, bridges and complex connections in the skeleton image after thinning. Burrs, bridges and complex connections on the ridge are processed separately by improved angle calculation method and the ridge length threshold. The slope method is used in the repair of break ridges.(3) Minutiae extraction and classification algorithms of fingerprints are researched. The existed minutiae extraction and classification algorithms are reviewed. A tow-stage fingerprint classification algorithm based on the Support Vector Machine is presented. Using the superiority of SVM to solve tow-class classification problems, we designed a tow-stage fingerprint classifier, presented and realized a novel method about fingerprint classification.(4) The commonly fingerprint identification algorithms based on theminutiae matching are studied. In order to improve the robustness of fingerprint matching algorithm, a contour-based fingerprint identification algorithm is presented, in which contour sets are used as the matching parameters, and so the affect of noises is small.(5) The application of AFIS in the background of the identification system of retirement pension payoff is studied. The background, modeling programming and implementation of the system are expounded. The UML is used as the visual modeling language. The Rational Rose is used as modeling tool. The object-oriented analysis and design ideas are introduced in the on-line fingerprint-verification-based pension payoff system. Rational Unified Process (RUP) is used in the design process. Based on the analysis of the bank system mechanism, a communication protocol conversion device between AFIS and bank system is designed. The flow of pension payment is similar to the general payment in the bank. The retiree can receive the pension payment after pressing fingerprint when he receives the hint to input the password. The flow does not affect other operation of the bank. Thus, the on-line fingerprint identification of pension payment is implemented and the identity verification can be carried in real time. The system has been successfully operated in a region of Shandong province, which solved the imitating drawing problem of the retirement pension to a great extent. The system is of great social benefit, and of great spread value.(6) The work of this thesis is summarized, and the directions of future work are given.According to literature search and science and technology query, the following points have not been reported identically which are the main innovation points of this paper.(1) A practical synthesis evaluation method of fingerprint image is proposed. The parameters of rough evaluation and fine evaluation are introduced. Rough evaluation and fine evaluation are used in registrationprocess. So the reliability of fingerprint template is guaranteed. Only rough evaluation is adopted in identification process to accelerate the identification.(2) The fingerprint image enhancement algorithm based on adaptive filter is proposed and adopted. It is efficient and effective. It was compared with an algorithm based on the curvelet transform, which has the character of orientation. The edges of ridge and valley are enhanced through the modification of the curvelet transform parameters. The experimental results show that the algorithm based on the curvelet transform is effective but is very complicated, and its efficiency is lower than the algorithm based on adaptive filter.(3) An expert-experience-based fingerprint image repair algorithm is used to repair the fingerprint skeleton image. The calculation method of angles is improved. Combined with the ridge length threshold, burrs, bridges and complex connections on the ridge are processed separately. The slope method is used in the repair of break ridges.(4) A tow-stage fingerprint classification algorithm based on the Support Vector Machine is realized. Different characters of singular points are used as the distinguishing rule. Using the superiority of SVM to solve tow-class classification problems, we designed a tow-stage fingerprint classifier, presented and realized a novel method about fingerprint classification.(5) A contour-based fingerprint identification algorithm is presented, in which contour sets are used as the matching parameters. So the affect of noises is small and the robustness is high.(6) The fingerprint identification technique is successfully applied in the on-line fingerprint identification system of retirement pension payment.更多还原