基于粒子群优化的支持向量机人脸识别

针对传统主成分分析(PCA)算法提取人脸特征时效率低下的问题,对其求解样本协方差矩阵的特征值和特征向量的过程进行改进,提出一种基于快速PCA降维算法的人脸识别方法。使用交叉验证方法,将支持向量机(SVM)模型训练时的识别准确率作为粒子群的适应度值,利用粒子群优化算法对SVM惩罚参数和核函数参数进行全局寻优,得到参数的全局最优解,用于训练最终的分类器模型进行人脸识别。通过对ORL和Yale数据库中的人脸图像进行实验,结果表明,与传统PCA算法结合SVM模型的识别方法相比,该方法对于人脸图像具有更高的特征提取效率及识别准确率。     

一种基于人脸垂直对称性的变形2DPCA算法

本文分析了人脸的对称性和主成分分析法(PCA)、二维主成分分析法(2DPCA)的特性,证明了2DPCA协方差矩阵就是PCA协方差矩阵的主角线的平均值,同时表明2DPCA减少了对人脸识别有用的协方差信息。提出了一种基于人脸垂直对称性的变形2DPCA算法(S2DPCA),该算法最大程度地利用了协方差鉴别信息,用更少的系数表示一张人脸图像。通过在ORL的实验比较表明,该算法与PCA算法相比降低了计算复杂性,与2DPCA方法和PCA方法相比提高了人脸识别率,在识别率方面优于传统算法(PCA(Eigenfaces)、ICA、Kernel Eigenfaces),同时也压缩了人脸的存储空间。     

基于多级纹理频谱特征与PCA的人脸识别算法

针对主成分分析(PCA)算法在人脸识别中识别率低的问题,提出一种图像纹理频谱特征与PCA相结合的人脸识别算法。该算法利用纹理单元算子提取人脸图像纹理频谱特征,然后用PCA对所提取的特征降维,最后利用最近邻(KNN)分类器进行人脸识别。在ORL人脸库和Yale人脸库上对所提出的算法进行了测试,识别率均高于PCA、模块化二维PCA(M2DPCA)等方法,分别为96.5%和95%。实验结果表明了该算法的有效性和准确性。     

改进的PCA-LDA人脸识别算法的研究

主成分分析算法(PCA)和线性鉴别分析算法(LDA)被广泛用于人脸识别技术中,但是PCA由于其计算复杂度高,致使人脸识别的实时性达不到要求.线性鉴别分析算法存在"小样本"和"边缘类"问题,降低了人脸识别的准确性.针对上述问题,提出使用二维主成分分析法(2DPCA)与改进的线性鉴别分析法相融合的方法.二维主成分分析法提取...     

小波变换和特征加权融合的人脸识别

在人脸识别领域,提取人脸特征和降低维数是人脸识别的关键。传统的基于小波变换的人脸识别算法仅在小波分解的低频分量上提取用于分类的图像特征,造成了高频分量中部分对识别有利信息的丢失。为了更有效地提取人脸图像特征,提出一种基于小波变换和特征加权融合的人脸识别算法。首先通过小波变换对人脸图像进行降维处理,然后对4个小波子图分别运用主成分分析法(PCA)提取特征,并把这4部分特征加权融合,最后利用支持向量机(SVM)进行分类识别。在ORL人脸库上进行实验验证,识别准确率可达到97.5%,实验结果表明该算法能够有效提高人脸识别能力,与传统识别算法相比具有较高的识别准确率和识别速度。     

基于稀疏化双向二维主成分分析的人脸识别

双向二维主成分分析((2D)~2PCA)易受异常值影响,鲁棒性差,且所提取的特征向量是非稀疏的。针对上述不足,提出基于L_1范数的稀疏双向二维主成分分析方法(2D)~2PCA-L1S。在(2D)~2PCA目标函数中加入L_1范数约束,以提高算法的抗干扰能力,同时引入弹性网约束,通过Lasso与Ridge惩罚函数实现稀疏性。在Feret和Yale数据库中进行基于最近邻的人脸分类、人脸重构和基于粒子群优化SVM参数的人脸识别实验,结果表明,相较于2DPCA、(2D)~2PCA、(2D)~2PCA-L1等主成分分析方法,该方法能准确提取人脸主要信息,人脸识别和人脸重构效果较好。     

基于分块2DPCA的人脸识别方法

为进一步提高分块二维主成分分析(2DPCA)算法在人脸识别的识别率,提出一种人脸识别算法.将训练样本人脸矩阵按光照等相似条件进行分块并进行类内平均归一化;采用2DPCA算法构造特征空间,将分块矩阵在特征空间中进行投影得到训练样本识别特征,利用支持向量机(SVM)在分类上的优势,对训练样本识别特征和经过归一化分块2DPCA的测试样本识别特征进行分类,对人脸图像进行识别.选取ORL人脸数据库的图片进行实验,将该算法与传统2DPCA、2DPCA+SVM等算法进行比较,验证了该算法的性能优于其它算法.     

基于差空间的双向2DPCA和SVM人脸识别算法

为降低SVM人脸识别算法对样本进行训练和识别的时间,提出了一种改进的基于差空间的双向2DPCA(Bidircctional two dimensions PCA)和SVM相结合的人脸识别算法。该方法充分考虑了表情和光照对人脸图像的影响,不但利用小波变换对人脸图像进行预处理,而且成功地把类内平均引入到双向2DPCA的计算中,并结合了SVM在分类识别方面的优势,有效节省了算法所需的时间。在Yale人脸库上的实验表明,它不但可以提高识别率,而且所用时间明显减少。     

基于二阶双向二维主成分分析的人脸识别方法

为了克服光照变化较大的情况对识别率的影响,提出基于二阶双向二维主成分分析(Sec-(2D)2PCA)的人脸识别方法。丢弃提取人脸图像的(2D)2PCA的前几个反映光照信息的主成分。在剩余图像中再次使用(2D)2PCA方法。Yale人脸库B和Yale人脸库上的试验结果表明,该方法在识别性能上优于2DPCA、(2D)2PCA、Sec-2DPCA方法。     

双向压缩的2DPCA与PCA相结合的人脸识别算法

主成分分析(PCA)直接用于人脸识别时,需将图像矩阵转换成向量,导致求解高阶矩阵计算量大.二维主成分分析(2DPCA)的实质是对图像矩阵按行进行图像压缩抽取特征,消除了图像列的相关性,但特征教量仍然较大,影响分类速度.针对这一问题,提出了采用双向压缩的二维主成分分析消除图像行间和列间的相关性,再结合PCA进一步减少特征数量,改进人脸识别算法,该算法用于ORL人脸库上得到了较高的识别率和较快的识别速度.     

二维主元分析在人脸识别中的应用研究

结合二维主元分析（two-dimensional principal component analysis,2DPCA）的特点,将2DPCA算法用于人脸识别。它与主元分析（principal component analysis,PCA）的不同之处在于,2DPCA算法以图像矩阵为分析对象;而PCA算法以图像的一维向量为分析对象。2DPCA算法是直接利用原始图像矩阵构造图像的协方差矩阵。而PCA算法需对原始图像矩阵先降维、再将降维矩阵转换成列向量,然后构造图像的协方差矩阵。为了测试和评估2DPCA算法的性能,在ORL（olivetti research laboratory）与Yale人脸数据库上进行了实验,结果表明,2DPCA算法用于人脸识别的正确识别率高于PCA算法。同时,也显示了2DPCA算法在特征提取方面比PCA算法更有效。     

基于混沌灰狼优化算法的SVM分类器研究

支持向量机(SVM)是在分类问题下建立的一个运算小型数据集,可实现非线性高纬度分类,有很好的扩展能力。但是,在传统SVM的训练过程中,SVM运算结果的好坏与参数选择关系密切,而且目前使用的参数选择算法有很多缺陷。因此,针对上述问题,在灰狼算法（GWO）中加入混沌序列,改变狼群初始分布规律,构建混沌灰狼优化算法(CGWO),增强狼群分布均匀性以及狼群查找遍历性,极大提高GWO算法的运算速度和运算准确性,最终更好地优化SVM。使用Mirjalili提供的开源数据与原有数据混合作为向量机的测试集进行实验对比分析,实验结果表明,CGWO算法具有明显的性能提高;用混沌灰狼算法优化的 SVM和灰狼优化算法SVM、人工蜂群SVM、万有引力搜索SVM以及传统算法优化的 SVM相比,其运算准确率更高、误差更低、花费时间更少。     

Color face recognition based on quaternion matrix representation

There are several methods to recognize and reconstruct a human face image. The principal component analysis (PCA) is a successful approach because of its effective extraction of the global feature and excellent reconstruction of face image. However, the crucial shortcomings of PCA are its low recognition rate and overfitting of feature extraction which leads to the dependence of training data on training samples. In this paper, a modified two-dimension principal component analysis (2DPCA) and bidirectional principal component analysis (BDPCA) methods based on quaternion matrix are proposed to recognize and reconstruct a color face image. In these methods, the spatial distribution information of color images is used to represent a color face, and the 2DPCA or BDPCA feature of color face image is extracted by reducing the dimensionality in both column and row directions. A method obtaining orthogonal eigenvector set of quaternion matrix is proposed. Numerous experiments show that the present approach based on quaternion matrix can effectively smooth the overfitting issue and substantially enhance the recognition rate.     

Two-dimensional PCA: a new approach to appearance-based face representation and recognition

In this paper, a new technique coined two-dimensional principal component analysis (2DPCA) is developed for image representation. As opposed to PCA, 2DPCA is based on 2D image matrices rather than 1D vectors so the image matrix does not need to be transformed into a vector prior to feature extraction. Instead, an image covariance matrix is constructed directly using the original image matrices, and its eigenvectors are derived for image feature extraction. To test 2DPCA and evaluate its performance, a series of experiments were performed on three face image databases: ORL, AR, and Yale face databases. The recognition rate across all trials was higher using 2DPCA than PCA. The experimental results also indicated that the extraction of image features is computationally more efficient using 2DPCA than PCA.     

关于二维主成分分析方法的研究

The principal component analysis (PCA), or the eigenfaces method, is a de facto standard in human face recognition. Numerous algorithms tried to generalize PCA in different aspects. More recently, a technique called two-dimensional PCA (2DPCA) was proposed to cut the computational cost of the standard PCA. Unlike PCA that treats images as vectors, 2DPCA views an image as a matrix. With a properly defined criterion, 2DPCA results in an eigenvalue problem which has a much lower dimensionality than that of PCA. In this paper, we show that 2DPCA is equivalent to a special case of an existing feature extraction method, i.e., the block-based PCA. Using the FERET database, extensive experimental results demonstrate that block-based PCA outperforms PCA on datasets that consist of relatively simple images for recognition, while PCA is more robust than 2DPCA in harder situations.     

基于PCA和LDA结合的人脸识别方法的比较研究

针对用于人脸识别的主分量分析(PCA)计算量大、识别效果不佳和分类时间长,线性判别分析(LDA)存在小样本问题,比较研究几种基于PCA和LDA的人脸识别方法,这些方法包括PCA+ LDA、2DPCA+ DLDA和2DPCA+2DLDA.在理论和实验上比较研究这些方法,且在ORL和Yale人脸库的实验数据表明,结合后的方法比结合前的方法分类效果好,分类时间短,且在这几种方法中,2DPCA+2DLDA的效果最佳.     

An adaptive neural networks formulation for the two-dimensional principal component analysis

This study, for the first time, developed an adaptive neural networks (NNs) formulation for the two-dimensional principal component analysis (2DPCA), whose space complexity is far lower than that of its statistical version. Unlike the NNs formulation of principal component analysis (PCA, i.e., 1DPCA), the solution with lower iteration in nature aims to directly deal with original image matrices. We also put forward the consistence in the conceptions of ‘eigenfaces’ or ‘eigengaits’ in both 1DPCA and 2DPCA neural networks. To evaluate the performance of the proposed NN, the experiments were carried out on AR face database and on 64 × 64 pixels gait energy images on CASIA(B) gait database. The less reconstruction error was exploited using the proposed NN in the condition of a large sample set compared to adaptive estimation of learning algorithms for NNs of PCA. On the contrary, if the sample set was small, the proposed NN could achieve a higher residue error than PCA NNs. The amount of calculation for the proposed NN here could be smaller than that for the PCA NNs on the feature extraction of the same image matrix, which represented an efficient solution to the problem of training images directly. On face and gait recognition tasks, a simple nearest neighbor classifier test indicated a particular benefit of the neural network developed here which serves as an efficient alternative to conventional PCA NNs.     

基于DCT融合2DPCA与DLDA的人脸识别

传统的基于主成分分析的人脸识别需要将图像矩阵转化为向量,特征提取需要花费大最时间.二维主成分分析直接利用图像矩阵,特征提取速度快,但特征数量大,影响分类速度.因此,提出了一种基于离散余弦变换(DCT)的二维主成分分析(2DPCA)和直接线性判决分析(DLDA)结合的人脸识别方法.算法首先用DCT对人脸图像进行压缩并重建,然后利用2DPCA和DLDA对人脸图像进行特征提取.最后选用最近邻分类器进行分类.在ORL人脸库上的测试结果表明,与DLDA或2DPCA算法相比,算法具有更高的识别率.     

Human face recognition based on ensemble of polyharmonic extreme learning machine

This paper proposes a classifier named ensemble of polyharmonic extreme learning machine, whose part weights are randomly assigned, and it is harmonic between the feedforward neural network and polynomial. The proposed classifier provides a method for human face recognition integrating fast discrete curvelet transform (FDCT) with 2-dimension principal component analysis (2DPCA). FDCT is taken to be a feature extractor to obtain facial features, and then these features are dimensionality reduced by 2DPCA to decrease the computational complexity before they are input to the classifier. Comparison experiments of the proposed method with some other state-of-the-art approaches for human face recognition have been carried out on five well-known face databases, and the experimental results show that the proposed method can achieve higher recognition rate.