A hybrid wavelet-based fingerprint matcher

In this work we present a hybrid fingerprint matcher system based on the multi-resolution analysis of the fingerprint pattern and on minutiae-based registration module. Two fingerprints are first aligned using their minutiae, then the images are divided in sub-windows and each sub-window is decomposed into frequency sub-bands at different decomposition levels using a set of wavelet functions, finally a distinct classifier is trained on each sub-band to distinguish matching pairs of fingerprint from non-matching one (defining a two-class matching problem). The features extracted for the matching are the standard deviation of the image convolved with 16 Gabor filters. The selection among the pool of matchers, is performed by running Sequential Forward Floating Selection. The retained matchers are weighted by a novel localized quality measure and combined by a fusion rule. Extensive experiments conducted over the four FVC2002 fingerprint databases show the effectiveness of the proposed approach.     

Combining flat and structured representations for fingerprint classification with recursive neural networks and support vector machines

We present new fingerprint classification algorithms based on two machine learning approaches: support vector machines (SVMs) and recursive neural networks (RNNs). RNNs are trained on a structured representation of the fingerprint image. They are also used to extract a set of distributed features of the fingerprint which can be integrated in the SVM. SVMs are combined with a new error-correcting code scheme. This approach has two main advantages: (a) It can tolerate the presence of ambiguous fingerprint images in the training set and (b) it can effectively identify the most difficult fingerprint images in the test set. By rejecting these images the accuracy of the system improves significantly. We report experiments on the fingerprint database NIST-4. Our best classification accuracy is of 95.6 percent at 20 percent rejection rate and is obtained by training SVMs on both FingerCode and RNN-extracted features. This result indicates the benefit of integrating global and structured representations and suggests that SVMs are a promising approach for fingerprint classification.     

Local binary patterns for a hybrid fingerprint matcher

In this work, we present a novel hybrid fingerprint matcher system based on local binary patterns. The two fingerprints to be matched are first aligned using their minutiae, then the images are decomposed in several overlapping sub-windows, each sub-window is convolved with a bank of Gabor filters and, finally, the invariant local binary patterns histograms are extracted from the convolved images.Extensive experiments conducted over the four FVC2002 fingerprint databases show the effectiveness of the proposed hybrid approach with respect to the well-known Tico's minutiae matcher and other image-based approaches. Moreover, a BioHashing approach have been designed using the proposed fixed-length feature vector and very interesting performance has been obtained by combining it with the Tico's minutiae matcher.     

Dynamic registration selection for fingerprint verification

Information fusion is a powerful approach to increasing the accuracy of biometric authentication systems, and is currently an active area of research. The majority of studies focus on combining the results from multiple verification systems at the match score level using either a classification or combination scheme. However, there are advantages to performing the fusion at an earlier stage of processing. Fingerprint registration involves finding the translation and rotation parameters that align two fingerprints; a challenging problem that can be approached in a number of ways. The fusion of fingerprint alignment algorithms is introduced in the form of dynamic registration selection. A Bayesian statistical framework is used to select the most probable alignment produced by competing algorithms. The results of the proposed technique are tested on multiple FVC 2002 databases, and are shown to outperform methods based on match score combination.     

Personal identity verification by serial fusion of fingerprint and face matchers

The use of personal identity verification systems with multi-modal biometrics has been proposed in order to increase the performance and robustness against environmental variations and fraudulent attacks. Usually multi-modal fusion of biometrics is performed in parallel at the score-level by combining the individual matching scores. This parallel strategy exhibits some drawbacks: (i) all available biometrics are necessary to perform fusion, thus the verification time depends on the slowest system; (ii) some users could be easily recognizable using a certain biometric instead of another one and (iii) the system invasiveness increases. A system characterized by the serial combination of multiple biometrics can be a good trade-off between verification time, performance and acceptability. However, these systems have been poorly investigated, and no support for designing the processing chain has been given so far. In this paper, we propose a novel serial scheme and a simple mathematical model able to predict the performance of two serially combined matchers as function of the selected processing chain. Our model helps the designer in finding the processing chain allowing a trade-off, in particular, between performance and matching time. Experiments carried out on well-known benchmark data sets made up of face and fingerprint images support the usefulness of the proposed methodology and compare it with standard parallel fusion.     

Learning fingerprint minutiae location and type

For simplicity of pattern recognition system design, a sequential approach consisting of sensing, feature extraction and classification/matching is conventionally adopted, where each stage transforms its input relatively independently. In practice, the interaction between these modules is limited. Some of the errors in this end-to-end sequential processing can be eliminated, especially for the feature extraction stage, by revisiting the input pattern. We propose a feedforward of the original grayscale image data to a feature (minutiae) verification stage in the context of a minutiae-based fingerprint verification system. This minutiae verification stage is based on reexamining the grayscale profile in a detected minutia's spatial neighborhood in the sensed image. We also show that a feature refinement (minutiae classification) stage that assigns one of two class labels to each detected minutia (ridge ending and ridge bifurcation) can improve the matching accuracy by ∼1% and when combined with the proposed minutiae verification stage, the matching accuracy can be improved by ∼3.2% on our fingerprint database.     

支持向量机处理大规模问题算法综述

支持向量机在处理大规模问题时存在训练时间过长和内存空间需求过大的问题.分析了支持向量机在处理大规模问题时存在的局限性;对利用支持向量机处理大规模问题的各种算法进行了分类,并对每种算法的研究状况进行了较全面而深入的综述;对该领域内值得进一步研究的问题进行了讨论.     

基于支持向量机的人脸识别方法

1.引言人脸是人类视觉中的常见模式,人脸识别在安全验证系统、公安(犯罪识别等)、医学、视频会议、交通量控制等方面有着广阔的应用前景。现有的基于生物特征的识别技术,包括语音识别、虹膜识别、指纹识别等,都已用于商业应用。然而最吸引人的还是人脸识别,因为从人机交互的方式来看,人脸识别更符合人们的理想。虽然人能毫不费力地识别出人脸及其表情,但人脸的机器自动识别仍然是一个具挑战性的研究领域。由于人脸结构的复杂性以及人脸表情的多样性、成像过     

最小方差支撑向量回归

基于支撑向量回归(SVR)可以通过构建支撑向量机分类问题实现的基本思想,推广最小类方差支撑向量机(MCVSVMs)于回归估计,提出了最小方差支撑向量回归(MVSVR)算法.该方法继承了MCVSVMs鲁棒性和泛化能力强的优点,分析了MVSVR和标准SVR之间的关系,讨论了在散度矩阵奇异情况下该方法的求解问题,同时也讨论了MVSVR的非线性情况.实验表明,该方法是可行的,且表现出了更强的泛化能力.     

一种确定高斯核模型参数的新方法

支持向量机中核函数及其参数的选择非常重要,该文提出了一种利用支持向量之间的距离求取高斯核函数参数的有效方法。该方法充分利用了支持向量机方法的最优判别函数仅仅与支持向量有关,并且支持向量为高斯核中心的特点。实验结果表明,该方法较好地反映了图像特征的本质,解决了高斯核函数参数在实际使用中不易确定的问题。     

Cycle-breaking acceleration for support vector regression

Support vector regression (SVR) is a powerful tool in modeling and prediction tasks with widespread application in many areas. The most representative algorithms to train SVR models are Shevade et al.'s Modification 2 and Lin's WSS1 and WSS2 methods in the LIBSVM library. Both are variants of standard SMO in which the updating pairs selected are those that most violate the Karush-Kuhn-Tucker optimality conditions, to which LIBSVM adds a heuristic to improve the decrease in the objective function. In this paper, and after presenting a simple derivation of the updating procedure based on a greedy maximization of the gain in the objective function, we show how cycle-breaking techniques that accelerate the convergence of support vector machines (SVM) in classification can also be applied under this framework, resulting in significantly improved training times for SVR.     

A kernel trick for sequences applied to text-independent speaker verification systems

This paper presents a principled SVM based speaker verification system. We propose a new framework and a new sequence kernel that can make use of any Mercer kernel at the frame level. An extension of the sequence kernel based on the Max operator is also proposed. The new system is compared to state-of-the-art GMM and other SVM based systems found in the literature on the Banca and Polyvar databases. The new system outperforms, most of the time, the other systems, statistically significantly. Finally, the new proposed framework clarifies previous SVM based systems and suggests interesting future research directions.     

基于支持向量机的多分类增量学习算法

支持向量机被成功地应用在分类和回归问题中，但是由于其需要求解二次规划，使得支持向量机在求解大规模数据上具有一定的缺陷，尤其是对于多分类问题，现有的支持向量机算法具有太高的算法复杂性。该文提出一种基于支持向量机的增量学习算法，适合多分类问题，并将之用于解决实际问题。     

基于Matlab的支持向量机工具箱

介绍了基于MATLAB的支持向量机工具箱,详细说明了工具箱中用于支持向量分类和支持向量回归的函数.并通过两个具体的实例来说明利用SVM工具箱进行分类和回归方面的方法.     

互补支持向量机

基于支持向量机的修正模型,得到一个互补支持向量机。利用Fischer-Burmeister互补函数,提出了一个新的下降算法。该算法不是基于支持向量机最优化问题本身,而是一个与之等价的互补问题。新算法不需要计算任何Hesse矩阵或矩阵求逆运算,实现简单,计算量小,克服了Mangasarian等人提出的LSVM算法需要求逆矩阵而造成不适合求解大规模非线性分类问题的缺陷。在不需要任何假设的情况下,证明了算法的全局收敛性。仿真实验表明算法是可行有效的。     

A comparative study of combining multiple enrolled samples for fingerprint verification

In fingerprint verification systems, there are usually multiple (from two to four) enrolled impressions for a same finger. The performance of the systems can be improved by combining these impressions through feature fusion or decision fusion strategy. In this paper, different schemes to combine multiple enrolled impressions are comparatively studied. Experimental results show that a larger improvement can be obtained by using decision fusion scheme than feature fusion. In all decision fusion rules, sum rule outperforms voting rule a little whether using similarity or Neyman-Pearson rule. Based on the observation that the performance of these two strategies can complement each other, we also propose a novel fusion scheme to further combine feature fusion and decision fusion, which can produce an even better result.     

最小二乘双支持向量机的在线学习算法

针对具有两个非并行分类超平面的最小二乘双支持向量机,提出了一种在线学习算法。通过利用矩阵求逆分解引理,所提在线学习算法能充分利用历史的训练结果,避免了大型矩阵的求逆计算过程,从而降低了计算的复杂性。仿真结果验证了所提学习算法的有效性。