A review of phosphorescent and fluorescent phosphors for fingerprint detection

Currently, the efficient detection of fingerprints is essential for the crime investigations. Revealing fingerprints is commonly achieved with fluorescent organic compounds but they are not efficient for fingerprint detection on porous or reflective surfaces. In order to solve the problem of collecting fingerprints on porous/reflective surfaces, inorganic phosphors have been employed, since they have characteristics of variable color emission, afterglow, high chemical stability and nano-size, which allow the fingerprint detection on any porous or non-porous surfaces. Due to these last properties, this review presents a summary about the use of phosphorescent and fluorescent phosphors for the detection of latent fingerprints. First, we discussed the main physical and chemical characteristics of the fingerprints which permit their detection and collection from any surface. After this, we presented the main morphological, structural and luminescent properties of the phosphorescent and fluorescent phosphors that allow their use for fingerprint detection. Later, we demonstrated with pictures of fingerprints (with and without light emission from the phosphors deposited on them) that both, phosphorescent and fluorescent phosphors can be used to visualize fingerprints with high resolution and high contrast without interference of the background surface, which is ideal for its collection and registration in the Automated Fingerprint Identification System (AFIS). We believe that this review could be useful to understand how to select an appropriate phosphorescent or fluorescent material for fingerprint detection depending on the type of surface (porous or non-porous, reflective or not reflective) where the fingerprint is deposited.     

基于模糊判别的指纹识别算法探讨

指纹识别在社会各个领域应用都非常广泛.本文从指纹识别的原理和应用出发,介绍一种基于模糊判别的指纹识别算法.     

指纹细节特征提取与剪枝

指纹图像经预处理后，由于各种原因，会产生数以百计的特征。为了图像匹配的精确和快速，提出一套在细化后的指纹点线图上提取细节特征并对其剪枝的方法，并根据细节特征的拓扑特性，设计了验证其可靠性的算法。通过实验，证明了该后处理过程在去除指纹图像伪特征方法面具有良好的效果。     

Two-class fingerprint matcher

We present a system for fingerprint verification that approaches the problem as a two-class pattern recognition problem. The features extracted by “FingerCode” are used to capture the ridge strength. This feature vector is then classified as genuine or impostor according to a novel approach to handle the fingerprint verification as a two-class problem. Moreover, we show that extracting the features from sub-images around the core permits to better represent the local information.     

指纹图像预处理的研究

对一种基于Gabor滤波的指纹图像增强方法进行讨论并加以实现。由于局部指纹纹线脊谷交错,近似平面正弦波,其傅立叶频谱具有明显的峰值,且峰值的方向和位置取决于纹线的方向和频率,因此采用具有良好方向和频率选择特性的Gabor滤波器可以实现较好的增强效果。在这种指纹图像增强方法中,关键是如何准确地计算指纹纹线方向和纹线频率。详细介绍指纹图像的预处理方法包括指纹图像的分割和增强,并给出增强算法的流程及实验结果。     

基于指纹认证的行车安全系统设计

汽车应用的普及带来汽车安全的隐患,基于指纹认证的行车安全系统可实现对驾驶员信息认证、汽车行驶过程、行驶状况、道路状况和交通信息的实时监控,有效预防汽车行驶的安全问题。详细阐述行车安全系统的功能、系统模块设计、硬件系统设计和软件系统设计,分析汽车终端模块的硬件结构和软件功能实现方法,给出基于VC＋＋的汽车终端功能实现的数据类。通过测试,系统能实时、准确地获取汽车行驶的动态数据,有效实现汽车安全管理。     

An alignment-free fingerprint bio-cryptosystem based on modified Voronoi neighbor structures

Bio-cryptography is an emerging security technology which combines cryptography with biometrics. A good bio-cryptosystem is required to protect the privacy of the relevant biometric data as well as achieving high recognition accuracy. Fingerprints have been widely used in bio-cryptosystem design. However, fingerprint uncertainty caused by distortion and rotation during the image capturing process makes it difficult to achieve a high recognition rate in most bio-cryptographic systems. Moreover, most existing bio-cryptosystems rely on the accurate detection of singular points for fingerprint image pre-alignment, which is very hard to achieve, and the image rotation transformation during the alignment process can cause significant singular point deviation and minutiae changes. In this paper, by taking full advantage of local Voronoi neighbor structures (VNSs), e.g. local structural stability and distortion insensitivity, we propose an alignment-free bio-cryptosystem based on fixed-length bit-string representations extracted from modified VNSs, which are rotation- and translation-invariant and distortion robust. The proposed alignment-free bio-cryptosystem is able to provide strong security while achieving good recognition performance. Experimental results in comparison with most existing alignment-free bio-cryptosystems using the publicly-available databases show the validity of the proposed scheme.     

3D fingerprint reconstruction system using feature correspondences and prior estimated finger model

The paper studies a 3D fingerprint reconstruction technique based on multi-view touchless fingerprint images. This technique offers a solution for 3D fingerprint image generation and application when only multi-view 2D images are available. However, the difficulties and stresses of 3D fingerprint reconstruction are the establishment of feature correspondences based on 2D touchless fingerprint images and the estimation of the finger shape model. In this paper, several popular used features, such as scale invariant feature transformation (SIFT) feature, ridge feature and minutiae, are employed for correspondences establishment. To extract these fingerprint features accurately, an improved fingerprint enhancement method has been proposed by polishing orientation and ridge frequency maps according to the characteristics of 2D touchless fingerprint images. Therefore, correspondences can be established by adopting hierarchical fingerprint matching approaches. Through an analysis of 440 3D point cloud finger data (220 fingers, 2 pictures each) collected by a 3D scanning technique, i.e., the structured light illumination (SLI) method, the finger shape model is estimated. It is found that the binary quadratic function is more suitable for the finger shape model than the other mixed model tested in this paper. In our experiments, the reconstruction accuracy is illustrated by constructing a cylinder. Furthermore, results obtained from different fingerprint feature correspondences are analyzed and compared to show which features are more suitable for 3D fingerprint images generation.     

一种基于稀疏表示的WLAN室内定位算法

随着科技进步和人民生活水平的提高,越来越多的用户对定位技术需求变得日益迫切。基于WLAN的室内定位技术研究在此背景下应运而生,但是该技术容易受非视距离以及多径影响。而位置指纹算法有效地克服了上述缺点,并得到了广泛应用。提出一种基于稀疏表示的WLAN室内定位算法,以解决位置指纹算法K近邻方法中参数选择问题、不能综合利用全局参考点信息问题,并对其进行了实验仿真。     

基于MATLAB指纹图像处理与识别的研究

该文利用专门的指纹采集设备获取指纹基本图像,基于MATLAB对指纹图像进行预处理,包括图像增强、图像二值化、分割和归一化。对指纹特征提取指纹类型、坐标和方向参数后,利用BP神经网络进行训练识别。识别实验效果明显,识别率高。