基于小波和最近邻凸包分类器的人脸识别

本文提出一种新型的人脸识别方法.该方法首先通过二维小波变换提取人脸图像的低频特征,然后采用最近邻凸包分类器对该特征进行分类.二维小波变换是提取图像特征的有效方法之一,在保留原始图像的主要特征的同时,还能够有效降低图像维数;最近邻凸包分类器是一种以测试样本点到各类别训练样本凸包的距离作为相似性度量的分类算法.本文将这两项技术相结合在ORL人脸识别数据库上取得了良好的实验效果.     

核最近邻凸包分类算法

为了增强最近邻凸包分类器的非线性分类能力,提出了基于核函数方法的最近邻凸包分类算法。该算法首先利用核函数方法将输入空间映射到高维特征空间,然后在高维特征空间采用最近邻凸包分类器对样本进行分类。最近邻凸包分类器是一类以测试点到各类别凸包的距离为相似性度量,并按最近邻原则归类的分类算法。人脸识别实验结果证实,这种核函数方法与最近邻凸包分类算法的融合是可行的和有效的。     

基于对称核主成分分析的人脸识别

为了提高人脸识别技术的实用性,结合人脸镜像对称性和核主成分分析提出了一种新的人脸识别方法。首先利用小波变换压缩人脸图像数据,获取小波分解的低频分量,再通过镜像变换得到镜像偶对称图像和镜像奇对称图像,然后分别对奇偶对称图像进行核主成分分析提取奇偶特征,并且通过加权因子对奇偶特征进行融合,最后采用最近邻分类器分类。基于ORL人脸数据库的实验结果表明：该算法增大了样本容量,在一定程度上克服了光照、姿态的不利因素,提高了人脸识别率。     

核子类凸包选样的核最近邻凸包分类器

为了保证核最近邻凸包分类器有效地处理大训练集的应用问题,本文提出一种与该分类器相结合的核子类凸包样本选择方法.核子类凸包样本选择方法是一个类内迭代算法,该算法在核空间里每次迭代选择一个距离选择集样本张成子类凸包最远的样本.在Head Pose Image Database系列1图像集上的实验中,本文方法不但可以取得较高的识别率,而且与未经选样的核最近邻凸包分类器相比,其执行速度要快许多.     

一种改进的基于奇异值扰动的单样本人脸识别方法

针对单训练样本情况下人脸识别性能不佳的问题,本文提出了一种改进的基于奇异值扰动的人脸识别方法。首先通过奇异值扰动方法扩展人脸样本,然后运用小波变换压缩扩展样本,选择小波变换分解后的低频分量作为子图像,再采用核主成分分析提取人脸的高阶特征,最后根据最近邻分类器分类。在ORL和Yale数据库上的仿真实验证明了本文方法的识别性能优于对比方法。     

核仿射子空间最近点分类算法

受支持向量机的几何解释和最近点问题启发,提出一种新型的模式分类算法——核仿射子空间最近点分类算法。该算法在核空间中,将支持向量机几何模型中的最近点搜索区域由2类训练特征集凸包推广到2类特征样本各自生成的仿射子空间,以仿射子空间作为特征样本分布的粗略估计,通过仿射子空间中的最近的2个点构造平分仿射子空间间隔的最优分类超平面。该算法在ORL人脸识别数据库上的比较实验中取得了较好的识别效果。     

Levy变异ABC算法优化二阶Volterra核的鲁棒人脸识别

针对人脸识别中由于人脸表情、姿态、尺度、光照和其他环境参数变化而影响识别性能的问题,提出了一种随机优化算法。首先,将原始图像划分成特定空间子块,并使用二阶Volterra核寻找非线性函数映射;然后,使用人工蜂群算法获取最优Volterra核,从而在特征空间内最大化类间距离并最小化类内距离;最后,利用投票策略和最近邻分类器完成人脸的分类。在两个通用人脸数据集Yale A和扩展Yale B上对该算法进行了评估,并将其与其他统计学习算法和几种最新提出的方法进行了比较。实验结果表明了Levy变异人工蜂群算法优化Volterra核的有效性,识别效果明显优于许多现有算法。     

基于深度学习与二维离散小波分解特征相融合的adaboost人脸识别模型

为了提高人脸识别的效率,本文提出了一种将小波分析、深度学习和adaboost分类器相结合的人脸识别方法。传统的基于小波变换的人脸识别算法仅仅提取了小波分解的低频分量用于分类图像的特征,为了更有效地提取人脸图像特征,提出了一种将传统特征和深度特征相融合的人脸识别算法。首先,通过二维离散小波变换函数对人脸图像进行二维离散小波变换,提取出人脸图像的低频部分作为特征值,接着通过深度残差网络提取人脸深度特征,最后将融合后的特征应用adaboost分类器进行分类识别。通过在ORL人脸库实验证明,融合后的方法能有效地提高分类识别率。     

核子空间样本选择方法的核最近邻凸包分类器

为了保证核最近邻凸包分类器有效地处理大训练集的应用问题,提出一种核子空间样本选择方法与该分类器相结合。核子空间样本选择方法是一个类内迭代算法,该算法在核空间里每次迭代选择一个距离选择集样本张成子空间最远的样本。在MIT-CBCL人脸识别数据库的training-synthetic子库上的实验中,该方法不但可以取得100%的识别率,而且与未经选样的核最近邻凸包分类器相比,其执行速度要快许多。     

优化的小波变换和改进的LDA相融合的人脸识别算法

提出了一种优化的小波变换与改进的LDA相融合的人脸识别算法。首先对经过预处理的人脸图像进行2层小波变换并提取特征,然后对小波分解后的高频子带进行融合,并在改进的LDA下利用交替方向法求出投影矩阵和最优融合系数,再结合低频子带在改进的LDA下的特征表示,利用最近邻分类器进行分类。实验结果表明,该算法在ORL及YALE人脸库上的识别效果较传统的人脸识别算法更优。     

Face recognition using spectral features

Face recognition is a challenging task in computer vision and pattern recognition. It is well-known that obtaining a low-dimensional feature representation with enhanced discriminatory power is of paramount importance to face recognition. Moreover, recent research has shown that the face images reside on a possibly nonlinear manifold. Thus, how to effectively exploit the hidden structure is a key problem that significantly affects the recognition results. In this paper, we propose a new unsupervised nonlinear feature extraction method called spectral feature analysis (SFA). The main advantages of SFA over traditional feature extraction methods are: (1) SFA does not suffer from the small-sample-size problem; (2) SFA can extract discriminatory information from the data, and we show that linear discriminant analysis can be subsumed under the SFA framework; (3) SFA can effectively discover the nonlinear structure hidden in the data. These appealing properties make SFA very suitable for face recognition tasks. Experimental results on three benchmark face databases illustrate the superiority of SFA over traditional methods.     

Learning the kernel matrix by maximizing a KFD-based class separability criterion

The advantage of a kernel method often depends critically on a proper choice of the kernel function. A promising approach is to learn the kernel from data automatically. In this paper, we propose a novel method for learning the kernel matrix based on maximizing a class separability criterion that is similar to those used by linear discriminant analysis (LDA) and kernel Fisher discriminant (KFD). It is interesting to note that optimizing this criterion function does not require inverting the possibly singular within-class scatter matrix which is a computational problem encountered by many LDA and KFD methods. We have conducted experiments on both synthetic data and real-world data from UCI and FERET, showing that our method consistently outperforms some previous kernel learning methods.     

A classifier for Bangla handwritten numeral recognition

This paper presents a novel pattern classification approach - a kernel and Bayesian discriminant based classifier which utilizes the distribution characteristics of the samples in each class. A kernel combined with Bayesian discriminant in the subspace spanned by the eigenvectors which are associated with the smaller eigenvalues in each class is adopted as the classification criterion. To solve the problem of the matrix inverse, the smaller eigenvalues are substituted by a small threshold which is decided by minimizing the training error in a given database. Application of the proposed classifier to the issue of handwritten numeral recognition demonstrates that it is promising in practical applications.     

Online face recognition system based on multi-view algorithm and Kernel PCA

An online face recognition system is presented in the paper. To online face recognition system, we should consider the recognition rate, the image compression and image size. In the paper we researched the innovation technologies for face recognition system, including Kernel Principal Component Analysis （Kernel PCA）, Delta low-pass wavelet filter, and face recognition algorithm using multiple images. Kernel PCA is derived to classify the characteristics of training images in the database. Delta low-pass wavelet filter is used to reduce the image size. A face recognition algorithm using multiple images is presented to improve the recognition rate. Simulation experiment shows that in the case of packet loss recognition rate is improved highly.     

Face recognition using difference vector plus KPCA

In this paper, a novel approach for face recognition based on the difference vector plus kernel PCA is proposed. Difference vector is the difference between the original image and the common vector which is obtained by the images processed by the Gram-Schmidt orthogonalization and represents the common invariant properties of the class. The optimal feature vectors are obtained by KPCA procedure for the difference vectors. Recognition result is derived from finding the minimum distance between the test difference feature vectors and the training difference feature vectors. To test and evaluate the proposed approach performance, a series of experiments are performed on four face databases: ORL, Yale, FERET and AR face databases and the experimental results show that the proposed method is encouraging.     

Face recognition using common faces method

In this paper, we propose a face recognition method called the commonface by using the common vector approach. A face image is regarded as a summation of a common vector which represents the invariant properties of the corresponding face class, and a difference vector which presents the specific properties of the corresponding face image such as face appearance, pose and expression. Thus, by deriving the common vector of each face class, the common feature of each person is obtained which removes the differences of face images belonging to the same person. For test face image, the remaining vector with each face class is derived with the similar procedure to the common vector, which is then compared with the common vector of each face class to predict the class label of query face by finding the minimum distance between the remaining vector and the common vector. Furthermore, we extend the common vector approach (CVP) to kernel CVP to improve the performance of CVP. The experimental results suggest that the proposed commonface approach provides a better representation of individual common feature and achieves lower error rates in face recognition.     

A reformative kernel Fisher discriminant analysis

A reformative kernel Fisher discriminant method is proposed, which is directly derived from the naive kernel Fisher discriminant analysis with superiority in classification efficiency. In the novel method only a part of training patterns, called “significant nodes”, are necessary to be adopted in classifying one test pattern. A recursive algorithm for selecting “significant nodes”, which is the key of the novel method, is presented in detail. The experiment on benchmarks shows that the novel method is effective and much efficient in classifying.     

Multiple Empirical Kernel Learning with dynamic pairwise constraints

Unlike the traditional Multiple Kernel Learning (MKL) with the implicit kernels, Multiple Empirical Kernel Learning (MEKL) explicitly maps the original data space into multiple feature spaces via different empirical kernels. MEKL has been demonstrated to bring good classification performance and to be much easier in processing and analyzing the adaptability of kernels for the input space. In this paper, we incorporate the dynamic pairwise constraints into MEKL to propose a novel Multiple Empirical Kernel Learning with dynamic Pairwise Constraints method (MEKLPC). It is known that the pairwise constraint provides the relationship between two samples, which tells whether these samples belong to the same class or not. In the present work, we boost the original pairwise constraints and design the dynamic pairwise constraints which can pay more attention onto the boundary samples and thus to make the decision hyperplane more reasonable and accurate. Thus, the proposed MEKLPC not only inherits the advantages of the MEKL, but also owns multiple folds of prior information. Firstly, MEKLPC gets the side-information and boosts the classification performance significantly in each feature space. Here, the side-information is the dynamic pairwise constraints which are constructed by the samples near the decision boundary, i.e. the boundary samples. Secondly, in each mapped feature space, MEKLPC still measures the empirical risk and generalization risk. Lastly, different feature spaces mapped by multiple empirical kernels can agree to their outputs for the same input sample as much as possible. To the best of our knowledge, it is the first time to introduce the dynamic pairwise constraints into the MEKL framework in the present work. The experiments on a number of real-world data sets demonstrate the feasibility and effectiveness of MEKLPC.     

核典型相关分析特征融合方法及应用

构建了一种基于核函数的典型相关分析的特征融合算法。首先,利用核函数将图像矩阵映射到核空间,再抽取同一模式的两组特征向量,在两组特征向量之间建立描述它们的相关性的判据准则函数;然后依此准则函数抽取两组典型投影矢量集;最后通过给定的特征融合策略抽取组合的典型相关特征以用于分类识别。该算法将两组特征向量之间的相关性特征作为有效鉴别信息,既可以很好地融合信息,又可以有效地去除特征之间的信息冗余,并且避免了对映射后的数据矩阵进行分解,从而简化了数据运算。在AR、PIE、ORL、Yale人脸数据库及UCI手写体数字库上的实验结果证明了该方法的有效性和稳定性。     

核方法在人脸识别中的应用

1 引言人脸识别技术广泛应用于身份验证、门检系统以及人员监视等方面,在过去的几年里,人脸识别技术有了很大的发展。人脸识别技术与普通的模式识别不同,主要是因为在一般的模式识别中,有几个分类,每个分类中有很多样本,这样可以安排大量样本进行训练;相反,人脸识别中通常会有很多不同的人脸,每个人脸代表一个分类,而每个分类中的样本数都比较少,在很多情况下,甚至每个人只有一张图片(如身份证照片),在文[4]中提出了处理只有一个样本情况下的人脸识别。