【作者】 刘锐；

【导师】 王学明；

【作者基本信息】 宁夏大学 ， 计算机软件与理论， 2014， 硕士

【摘要】 随着社会信息化的发展,个人信息的安全性承受着巨大的挑战,以指纹识别技术为代表的生物特征识别技术以其高准确性和可信度的特点成为解决信息安全性的方法之一。随着指纹技术的应用越来越广泛,大型指纹数据库成为当前研究的热点.如果不能构建有效的数据库索引机制,输入的指纹图像将必须同数据库中大量指纹数据逐一进行比对,系统将处于高负荷运转状态。为减少搜索时间和算法复杂度,必须使用关键字对数据库多级分类。因此,本文以基于大容量指纹库的指纹自动分类检索技术研究为主线,设计了一个三级指纹分类系统,大大提高了指纹检索效率。在指纹图像预处理、指纹特征提取、指纹分类检索等方面作了研究,主要研究成果有：1、在指纹的预处理阶段,在分析和吸取了国内外学者在指纹预处理算法的基础上,实现了指纹预处理过程中关键的处理步骤,包括指纹方向场求取、图像分割、图像增强、二值化和细化等,得到比较精确的图像数据。2、研究了一种基于全局特征与局部特征相结合的指纹质量评测方法。该方法根据不同的评测指标对指纹图像质量进行分级评估,对于质量不合格的指纹,立即终止其评估流程,提示用户重新输入指纹图像。3.研究了指纹特征提取算法,提出了一种分级式奇异点提取方法。先通过指纹图像的曲率估计初步确定奇异区,然后在奇异区内采用改进的Poincare索引值方法进行奇异点的精确定位。改进后的Poincare索引值方法的算法提高了指纹奇异点提取速度和精度,从而提高了指纹分类速度和正确率。4、对指纹分类算法进行了研究,为匹配大容量指纹数据库的快速匹配识别,提出了一种基于指纹纹形、奇异点间的脊线数目和脊线平均频率的三级指纹分类算法。通过实验数据对比和算法的性能分析,本算法检索效率高、鲁棒性强,为大数据量指纹库提供了一种高效的索引匹配机制。更多还原

【Abstract】 With the development of information society,Security of Personal Information faced tremendous challenge.Fingerprint recognition technology as the representative of biometrics technology for its high accuracy and reliability features is becoming one of the ways to solve the information security. When the application of fingerprint technology more is widely used, the research of large fingerprint database becomes a hotspot.If we don’t build a indexing mechanism for the databases input fingerprint image will be contrasted one by one with a large database of fingerprint and he system will be in a high-load operation state.To reduce the search time and complexity of the algorithm, the database must use the keyword to multi-levelly classify.Therefore.with the main research line of automated fingerprint classification and retrieval technology based on large-capacity fingerprint database, the paper designed a three-tier system of fingerprint classification.The efficiency of fingerprint retrieval is greatly improved.The paper gets a achievement in Ithe fingerprint image preprocessing, fingerprint feature extraction and fingerprint classification and retrieval.The main achievement are:1.In the pre-processing stage of fingerprints,the paper achieved the key process steps of Fingerprint preprocessing in the basis of analyzing and learning fingerprint preprocessing algorithm from domestic and foreign scholars.Including the fingerprint orientation computation, image segmentation, image enhancement, binarization and thinning to two and getting accurate results of image data.2.A new method based on the combination of global and local features is studied to evaluate the quality of fingerprints.The quality of fingerprint images is evaluated hierarchically through different evaluation indices. If the fingerprint image is not qualified, the process of evaluation is ended and the user is reminded to re-enter another one.3.Fingerprint feature extraction algorithm is studied, putting forward a method for extracting hierarchical singularity.In order to initially identify the singular region,the curvature of fingerprint image is estimated, then using improved algorithm of the Poincare index accurate positioning of the singular point value in the singular region.So that the modified version of poincare Index can locate the singularities quickly and exactly, and it can improve the speed and accuracy of Fingerprint Classification.4.The fingerprint classification algorithms is studied.In order to match fast matching recognition of large capacity fingerprint database,designing a three-level Fingerprint Classification System, which using fingerprint pattern,Ridge Count and the average ridge frequency as general characteristics of the fingerprint to classify fingerprint. Through the experiment data comparison and analysis algorithm, the retrieval algorithm of high efficiency, strong robustness, provides an efficient indexing mechanism for a large amount of data matching fingerprint database.更多还原