改进的保持邻域嵌入人脸识别方法

为进一步提高保持邻域嵌入算法在人脸识别中的识别性能,提出一种改进的保持邻域嵌入人脸识别方法LDNPE。利用先验的类标签信息构造权重矩阵,按照线性鉴别的思想把类间散布矩阵嵌入到目标函数中,增加样本类间散布约束,基于修改后的目标函数得到最优变换矩阵,并用最近距离分类器分类。在CAS-PEAL和FERET人脸数据库上的实验结果表明该算法的有效性。     

基于QR分解的正则化邻域保持嵌入算法

针对训练样本不足时,对数据的低维子空间估计可能会产生严重偏差的问题,提出了一种基于QR分解的正则化邻域保持嵌入算法。首先,该算法定义一个局部拉普拉斯矩阵保留原始数据的局部结构;其次,将类内散度矩阵的特征谱空间划分成三个子空间,通过倒数谱模型定义的权值函数获得新的特征向量空间,进而对高维数据进行预处理;最后,定义一个邻域保持邻接矩阵,利用QR分解获得的投影矩阵和最近邻分类器进行人脸分类。与正则化广义局部保持投影(RGDLPP)算法相比,所提算法在ORL、Yale、FERET和PIE库上识别率分别提高了2个百分点、1.5个百分点、1.5个百分点和2个百分点。实验结果表明,所提算法易于实现,在小样本(SSS)下有较高的识别率。     

A sparse neighborhood preserving non-negative tensor factorization algorithm for facial expression recognition

In this paper, a novel sparse neighborhood preserving non-negative tensor factorization (SNPNTF) algorithm is proposed for facial expression recognition. It is derived from non-negative tensor factorization (NTF), and it works in the rank-one tensor space. A sparse constraint is adopted into the objective function, which takes the optimization step in the direction of the negative gradient, and then projects onto the sparse constrained space. To consider the spatial neighborhood structure and the class-based discriminant information, a neighborhood preserving constraint is adopted based on the manifold learning and graph preserving theory. The Laplacian graph which encodes the spatial information in the face samples and the penalty graph which considers the pre-defined class information are considered in this constraint. By using it, the obtained parts-based representations of SNPNTF vary smoothly along the geodesics of the data manifold and they are more discriminant for recognition. SNPNTF is a quadratic convex function in the tensor space, and it could converge to the optimal solution. The gradient descent method is used for the optimization of SNPNTF to ensure the convergence property. Experiments are conducted on the JAFFE database, the Cohn–Kanade database and the AR database. The results demonstrate that SNPNTF provides effective facial representations and achieves better recognition performance, compared with non-negative matrix factorization, NTF and some variant algorithms. Also, the convergence property of SNPNTF is well guaranteed.     

基于加权多尺度张量子空间的人脸图像特征提取方法

为了不破坏原始数据固有的高阶结构和数据之间的相关性,减少光照对图像特征的影响,并优化多尺度特征的权重,提出了基于加权多尺度张量子空间的图像特征提取方法。采用多尺度小波变换表征图像各个 部位特征,使用不确定度权衡每个尺度对图像分类的作用,并组建成多尺度张量子空间,结合多线性主成分分析与线性判别分析算法,降低了图像在处理过程中的成本,保存了高维数据固有结构和相关性,完成对图像特征提取。使用CAS-PEAL-R1东方人脸库进行评测,实 验结果表明,该图像特征提取算法用于图像识别过程中具有较好的效果,具有一定的可行性。     

Kernel class-wise locality preserving projection

In the recent years, the pattern recognition community paid more attention to a new kind of feature extraction method, the manifold learning methods, which attempt to project the original data into a lower dimensional feature space by preserving the local neighborhood structure. Among them, locality preserving projection (LPP) is one of the most promising feature extraction techniques. However, when LPP is applied to the classification tasks, it shows some limitations, such as the ignorance of the label information. In this paper, we propose a novel local structure based feature extraction method, called class-wise locality preserving projection (CLPP). CLPP utilizes class information to guide the procedure of feature extraction. In CLPP, the local structure of the original data is constructed according to a certain kind of similarity between data points, which takes special consideration of both the local information and the class information. The kernelized (nonlinear) counterpart of this linear feature extractor is also established in the paper. Moreover, a kernel version of CLPP namely Kernel CLPP (KCLPP) is developed through applying the kernel trick to CLPP to increase its performance on nonlinear feature extraction. Experiments on ORL face database and YALE face database are performed to test and evaluate the proposed algorithm.     

一种改进的邻域保持嵌入算法

邻域保持嵌入(NPE)是一种新颖的子空间学习算法,在降维的同时保持了样本集原有的局部邻域流形结构。为了进一步增强NPE在人脸识别和语音识别中的识别功能,提出了一种改进的邻域保持嵌入算法(RNPE)。在NPE的基础上通过引入类间权值矩阵,使得类间离散度最大,类内离散度最小,增加了样本类间散布约束。最后利用极端学习机(ELM)分类器进行分类,在Yale人脸库、Umist人脸库、Isolet语音库上的实验结果表明,RNPE算法的识别率明显高于NPE算法、LMMDE算法以及RAF-GE算法。     

LPP solution schemes for use with face recognition

Locality preserving projection (LPP) is a manifold learning method widely used in pattern recognition and computer vision. The face recognition application of LPP is known to suffer from a number of problems including the small sample size (SSS) problem, the fact that it might produce statistically identical transform results for neighboring samples, and that its classification performance seems to be heavily influenced by its parameters. In this paper, we propose three novel solution schemes for LPP. Experimental results also show that the proposed LPP solution scheme is able to classify much more accurately than conventional LPP and to obtain a classification performance that is only little influenced by the definition of neighbor samples.     

无监督的差分鉴别特征提取以及在人脸识别上的应用

局部保持投影(LPP)只考虑了投影后的局部性,而忽视了非局部性.针对这个问题,引入非局部散布矩阵,提出无监督的差分鉴别特征提取算法,通过最大化非局部和局部之间的散度差来寻找最优变换矩阵,并将其成功地应用于人脸识别.该算法同时引入非局部和局部的信息,揭示隐含在高维图像空间中的非线性结构;采用差分的形式求解最优变换矩阵,以避免"小样本"问题;对LPP中的邻接矩阵进行了修正,以更准确地描述样本之间的邻近关系.在Yale和AR标准人脸库上的实验结果验证了文中算法的有效性.     

应用于人脸图像识别的邻域保持极限学习机

极限学习机广泛应用于人脸识别领域。传统的极限学习机算法因在少量标签样本上进行训练，容易发生学习过程不充分问题，同时在学习过程中往往忽略了样本内在的几何结构，影响其对人脸识别的分类能力。受流形学习思想的启发，提出一种邻域保持极限学习机算法。该算法保持数据最本质的结构和同类数据的判别信息，利用最小化类内散度矩阵来提高极限学习机整体的分类性能。通过人脸数据集上的多次实验结果表明，该算法的人脸识别准确率高于其他算法，更能有效地进行分类识别。     

A novel maximum margin neighborhood preserving embedding for face recognition

This paper presents a novel supervised linear dimensionality reduction approach called maximum margin neighborhood preserving embedding (MMNPE). The central idea is to modify the neighborhood preserving embedding by maximizing the maximum margin distance while preserving the geometric structure of the manifold. Experimental results conducted on the ORL database, the Yale database and the VALID face database indicate the effectiveness of the proposed MMNPE.     

Vector projection for face recognition

In this paper, a novel approach for face recognition is proposed by using vector projection length to formulate the pattern recognition problem. Face images of a single-object class are more similar than those of different-object classes. The projection length of a test image vector on the direction of a training image vector can measure the similarity of the two images. But the decision cannot be made by only a training image which is the most similar to the test one, the mean image vector of each class also contributes to the final classification. Thus, the decision of the proposed vector projection classification (VPC) algorithm is ruled in favor of the maximum combination projection length. To address the partial occlusion problem in face recognition, we propose a local vector projection classification (LVPC) algorithm. The experimental results show that the proposed VPC and LVPC approaches are efficient and outperform some existing approaches.     

张量描述下的多姿态多表情人脸合成方法

为了从一幅人脸图像中合成出该人脸其他姿态和表情下的图像,提出了一种基于张量子空间的多姿态人脸表情合成方法。首先,用标记过特征点的人脸图像集构造四维纹理特征张量和形状张量;其次,通过张量分解得到核张量以及各维的投影子空间(人物标识、表情、姿态、特征维);最后应用核张量以及表情、姿态子空间构造新的张量用于姿态、表情的合成,在合成新人脸图像的时候充分利用了影响人脸的各因素间的内在关系。实验结果表明,所提方法可以利用一张已知表情和姿态的人脸图合成出自然合理的其他姿态表情下的该人脸图像。     

Uncorrelated Multilinear Discriminant Analysis With Regularization and Aggregation for Tensor Object Recognition

This paper proposes an uncorrelated multilinear discriminant analysis (UMLDA) framework for the recognition of multidimensional objects, known as tensor objects. Uncorrelated features are desirable in recognition tasks since they contain minimum redundancy and ensure independence of features. The UMLDA aims to extract uncorrelated discriminative features directly from tensorial data through solving a tensor-to-vector projection. The solution consists of sequential iterative processes based on the alternating projection method, and an adaptive regularization procedure is incorporated to enhance the performance in the small sample size (SSS) scenario. A simple nearest-neighbor classifier is employed for classification. Furthermore, exploiting the complementary information from differently initialized and regularized UMLDA recognizers, an aggregation scheme is adopted to combine them at the matching score level, resulting in enhanced generalization performance while alleviating the regularization parameter selection problem. The UMLDA-based recognition algorithm is then empirically shown on face and gait recognition tasks to outperform four multilinear subspace solutions (MPCA, DATER, GTDA, TR1DA) and four linear subspace solutions (Bayesian, LDA, ULDA, R-JD-LDA).     

Regularized locality preserving discriminant analysis for face recognition

This paper proposes a regularized locality preserving discriminant analysis (RLPDA) approach for facial feature extraction and recognition. The RLPDA approach decomposes the eigenspace of the locality preserving within-class scatter matrix into three subspaces, i.e., the face space, the noise space and the null space, and then regularizes the three subspaces differently according to their predicted eigenvalues. As a result, the proposed approach integrates discriminative information in all of the three subspaces, de-emphasizes the effect of the eigenvectors corresponding to the small eigenvalues, and meanwhile suppresses the small sample size problem. Extensive experiments on ORL face database, FERET face subset and UMIST face database illustrate the effectiveness of the proposed approach.     

Sparse neighbor representation for classification

Recent research of sparse signal representation has aimed at learning discriminative sparse models instead of purely reconstructive ones for classification tasks, such as sparse representation based classification (SRC) which obtains state-of-the-art results in face recognition. In this paper, a new method is proposed in that direction. With the assumption of locally linear embedding, the proposed method achieves the classification goal via sparse neighbor representation, combining the reconstruction property, sparsity and discrimination power. The experiments on several data sets are performed and results show that the proposed method is acceptable for nonlinear data sets. Further, it is argued that the proposed method is well suited for the classification of low dimensional data dimensionally reduced by dimensionality reduction methods, especially the methods obtaining the low dimensional and neighborhood preserving embeddings, and it costs less time.     

无参数无相关最大化判别边界算法

在人脸识别算法中,无参数局部保持投影(PFLPP)是一种有效的特征提取算法, 但忽略了异类近邻样本在分类中所起的作用,并且对于近邻的处理仅利用样本与总体均值的 距离关系来判断,因此并不能有效地确定近邻关系。基于此,提出一种无参数无相关最大化 判别边界算法,有效地利用了样本的类别信息,定义了无参数同类近邻样本的相似权值与异 类近邻样本的惩罚权值,样本邻域大小可根据类内平均余弦距离和类间余弦距离自适应确定, 为了进一步增强算法的性能,给出了具有不相关性的目标函数。UMIST 和 AR 人脸库上的实 验结果表明,该算法相对于不相关保局投影分析算法和 PFLPP 算法,具有运算量低、识别性 能高的优势。     

Local structure based supervised feature extraction

In the past few years, the computer vision and pattern recognition community has witnessed the rapid growth of a new kind of feature extraction method, the manifold learning methods, which attempt to project the original data into a lower dimensional feature space by preserving the local neighborhood structure. Among them, locality preserving projection (LPP) is one of the most promising feature extraction techniques. However, when LPP is applied to the classification tasks, it shows some limitations, such as the ignorance of the label information. In this paper, we propose a novel feature extraction method, called locally discriminating projection (LDP). LDP utilizes class information to guide the procedure of feature extraction. In LDP, the local structure of the original data is constructed according to a certain kind of similarity between data points, which takes special consideration of both the local information and the class information. The similarity has several good properties which help to discover the true intrinsic structure of the data, and make LDP a robust technique for the classification tasks. We compare the proposed LDP approach with LPP, as well as other feature extraction methods, such as PCA and LDA, on the public available data sets, FERET and AR. Experimental results suggest that LDP provides a better representation of the class information and achieves much higher recognition accuracies.     

正交化近邻关系保持的降维及分类算法

针对近邻关系保持嵌入（NPE）算法易于受到降低后的维数影响,而且性能依赖于正确的维数估计的问题,提出了一种正交化的近邻关系保持的嵌入降维方法——ONPE。ONPE方法是使用数据点间的近邻关系来构造邻接图,假设每个数据点都能由其近邻点的线性组合表示,则可以通过提取数据点的局部几何信息,并在降维中保持提取的局部几何信息,迭代地计算正交基来得到数据的低维嵌入坐标。同时,在ONPE算法的基础上,利用局部几何信息,提出了一种在低维空间中使用标签传递（LNP）的分类算法——ONPC。其是假设高维空间中的局部近邻关系在降维后的空间中依然得到保持,并且数据点的类别可由近邻点的类别得到。在人工数据和人脸数据上的实验表明,该算法在减少维数依赖的同时,能有效提高NPE算法的分类性能。     

最小化TPE一元回归分类在人脸识别中的应用

针对人脸识别中现有回归分类方法不能很好地考虑总类内投影误差的问题,提出了一种基于最小化总投影误差（TPE）的一元回归分类方法。通过各个类投影矩阵计算所有训练数据的类内投影误差矩阵,并且借助特征分解找到一元旋转矩阵;利用一元旋转矩阵将每个训练图像向量转换为新的向量空间,并计算出每个类的特定投影矩阵;根据一元旋转子空间中各个类的最小投影误差来完成人脸的识别。在两大通用人脸数据库FEI和FERET上的实验验证了所提方法的有效性及鲁棒性,实验结果表明,相比其他几种先进的回归分类方法,所提方法取得了更好的识别效果。     

Maximal local interclass embedding with application to face recognition

Dimensionality reduction of high dimensional data is involved in many problems in information processing. A new dimensionality reduction approach called maximal local interclass embedding (MLIE) is developed in this paper. MLIE can be viewed as a linear approach of a multimanifolds-based learning framework, in which the information of neighborhood is integrated with the local interclass relationships. In MLIE, the local interclass graph and the intrinsic graph are constructed to find a set of projections that maximize the local interclass scatter and the local intraclass compactness simultaneously. This characteristic makes MLIE more powerful than marginal Fisher analysis (MFA). MLIE maintains all the advantages of MFA. Moreover, the computational complexity of MLIE is less than that of MFA. The proposed algorithm is applied to face recognition. Experiments have been performed on the Yale, AR and ORL face image databases. The experimental results show that owing to the locally discriminating property, MLIE consistently outperforms up-to-date MFA, Smooth MFA, neighborhood preserving embedding and locality preserving projection in face recognition.