基于改进初始化判别K SVD方法的人脸识别

基于稀疏表示的人脸识别问题希望字典同时具有良好的表示能力和较强的辨识性。采用判别式K SVD（D ksvd）算法,可训练得到较好的字典和线性判别函数,但该算法中的初始化字典是从各类样本中选择部分样本经K SVD方法得到的,不能较完整地表示所有样本的特性,影响了基于该初始字典的训练字典的表示能力和分类器的辨识性。在字典初始化方法上进行了改进,先训练类内字典再级联成新的初始化字典,由于类内训练字典是各类别的优化字典,降低了训练字典的误差,提高了训练字典与线性分类器的判别性,在保持较快识别速度的同时,提高了人脸识别率。     

Gabor特征集结合判别式字典学习的稀疏表示图像识别

稀疏编码中字典的选择无论对图像重建还是模式分类都有重要影响,为此提出Gabor特征集结合判别式字典学习的稀疏表示图像识别算法.考虑到Gabor局部特征对光照、表情和姿态等变化的鲁棒性,首先提取图像对应不同方向、不同尺度的多个Gabor特征;然后将降维的增广Gabor特征矩阵作为初始特征字典,通过对该字典的学习得到字典原子对应类别标签的新结构化字典,新字典中特定类的子字典对相关的类具有好的表示能力,同时应用Fisher判别约束编码系数,使它们具有小的类内散度和大的类间散度;最后同时用具有判别性的重构误差和编码系数来进行模式分类.基于3个数据库的实验结果表明本文方法具有可行性和有效性.     

基于特征优选和字典优化的组稀疏表示表情识别

针对在小样本人脸表情数据库上识别模型过拟合问题,文中提出基于特征优选和字典优化的组稀疏表示分类方法.首先提出特征优选准则,选择相同类级稀疏模式、不同类内稀疏模式的互补特征构建字典.然后对字典进行最大散度差优化学习,使字典在不失真重构特征的同时具有较高鉴别能力.最后联合优化后的字典进行组稀疏表示分类.在JAFFE、CK+...     

Sparse Representation Based Fisher Discrimination Dictionary Learning for Image Classification

The employed dictionary plays an important role in sparse representation or sparse coding based image reconstruction and classification, while learning dictionaries from the training data has led to state-of-the-art results in image classification tasks. However, many dictionary learning models exploit only the discriminative information in either the representation coefficients or the representation residual, which limits their performance. In this paper we present a novel dictionary learning method based on the Fisher discrimination criterion. A structured dictionary, whose atoms have correspondences to the subject class labels, is learned, with which not only the representation residual can be used to distinguish different classes, but also the representation coefficients have small within-class scatter and big between-class scatter. The classification scheme associated with the proposed Fisher discrimination dictionary learning (FDDL) model is consequently presented by exploiting the discriminative information in both the representation residual and the representation coefficients. The proposed FDDL model is extensively evaluated on various image datasets, and it shows superior performance to many state-of-the-art dictionary learning methods in a variety of classification tasks.     

面向人脸识别的判别低秩字典学习算法

人脸识别是计算机视觉和模式识别领域的一个研究热点,有着十分广泛的应用前景.人脸识别任务在训练样本和测试样本同时包含噪声的情况下存在识别精度不高的问题,为此本文提出一个新的判别低秩字典学习和低秩稀疏表示算法（Discriminative Low-Rank Dictionary Learning for Low-Rank Sparse Representation,DLRD_LRSR）.本文方法在模型中约束每个子字典和稀疏表示低秩避免噪声干扰,并引入了判别重构误差项增强系数的判别性.为验证算法的有效性,本文在3个公开人脸数据集上进行了实验评估,结果表明与现有字典学习算法相比,本文算法能够更好的解决训练样本和测试样本同时存在噪声的人脸识别问题.     

特征加权组稀疏判别投影分析算法

近来, 稀疏表示分类算法已经在模式识别和特征提取领域获得了广泛的关注. 受最近提出的稀疏表示判别投影算法启发, 本文提出了一种新的特征加权组稀疏判别投影算法(Feature weighted group sparse classification steered discriminative projection, FWGSDP). 首先, 提出特征加权组稀疏分类算法(Feature weighted group sparsebased classification, FWGSC)进行稀疏系数编码, 该算法采用带特征加权约束的保局性信息, 能够鲁棒地重构给定的输入数据; 其次, 通过类内重构散度最小、类间重构散度最大为目标计算最优投影判别矩阵, 使得输入数据具有最佳的模式分类效果; 最后, 提出迭代重约束稀疏编码方法并结合特征分解操作进行FWGSDP模型高效求解. 在ExYaleB, PIE和AR三个人脸数据库的实验验证了所提算法在普通数据和带噪数据中的分类效果都优于现存的算法.     

基于扩展字典稀疏表示分类的遥感目标识别

针对遥感图像视觉对比度差、分辨率低及目标含有不同角度旋转的情况,在稀疏表示分类识别的基础上,提出一种基于扩展字典稀疏表示的遥感目标识别方法。首先将训练样本和待测样本进行二进小波变换增强,提取增强图像的SIFT特征构成特征字典,并将原始的训练字典改为训练-特征扩展字典进行稀疏表示,从而使字典更加具有判别能力,提高识别率。同时,分析了SIFT特征经随机投影后对识别率的影响。实验表明,该方法对遥感图像目标识别具有较好的鲁棒性。     

基于Gabor特征和支持向量引导字典学习的人脸识别

稀疏编码中的字典学习在稀疏表示的图像识别中扮演着重要的作用。由于Gabor特征对表情、光照和姿态等变化具有一定的鲁棒性,提出一种基于Gabor特征和支持向量引导字典学习（GSVGDL）的稀疏表示人脸识别算法。先提取图像的Gabor特征,然后用增广Gabor特征矩阵来构造初始字典。字典学习模型中综合了重构误差项、判别项和正则化项,判别项公式化定义为所有编码向量对平方距离的加权总和;通过字典学习同时得到字典原子与类别标签相对应的结构化字典和线性分类器。该字典学习方法能够自适应地为不同的编码向量对分配不同的权值,提高了字典的判别性能。实验结果表明该方法具有很好的识别精度和较高的识别效率。     

流形结构化半监督扩展字典学习的旋转设备故障诊断

针对有标签数据不足及传统故障诊断模型判别性差的问题,本文提出一种流形结构化半监督扩展字典学习(MS-SSEDL)的故障诊断方法.首先,为改善缺少有标签数据而导致模型的识别性能较差问题,在MS-SSEDL模型中提出无标签数据重构误差项,利用无标签数据学习置信度矩阵,从而学习得到扩展字典以增强字典学习的表示性.然后,为增强MS-SSEDL模型的判别性,通过保存数据的流形结构,学习数据中内在几何信息的稀疏表示,增强信号表示能力及字典判别性.最后,在数字图像、轴承故障及齿轮故障公共数据集的实验表明所提MS-SSEDL方法比其他先进方法的识别性能更优越.     

Fisher准则下面向判别性特征的字典学习方法及其组织病理图像分类研究

针对当前面向组织病理图像特征提取的字典学习方法中存在着学习的无病字典与有病字典相似程度高,判别性弱的问题,本文提出一种新的面向判别性特征字典学习方法（Discriminative feature-oriented dictionary learning based on Fisher criterion,FCDFDL）.该方法基于Fisher准则构造目标函数的惩罚项,最小化学习字典的类内距离与最大化学习字典的类间距离,大大降低无病字典与有病字典间的相似性.同时,优化学习字典对同类样本的重构性能,并约束学习字典对非同类样本的重构性能.然后,利用本文学习的无病与有病字典对测试样本进行稀疏表示,采用重构误差向量的统计量构造分类器.最后,分别在ADL数据集与BreaKHis数据集上验证了本文方法的有效性.实验结果表明,本文学习字典的判别性更强,获得了更优的分类性能.     

Fractional-order Sparse Representation for Image Denoising

Sparse representation models have been shown promising results for image denoising. However, conventional sparse representation-based models cannot obtain satisfactory estimations for sparse coefficients and the dictionary. To address this weakness, in this paper, we propose a novel fractional-order sparse representation (FSR) model. Specifically, we cluster the image patches into K groups, and calculate the singular values for each clean/noisy patch pair in the wavelet domain. Then the uniform fractional-order parameters are learned for each cluster. Then a novel fractional-order sample space is constructed using adaptive fractional-order parameters in the wavelet domain to obtain more accurate sparse coefficients and dictionary for image denoising. Extensive experimental results show that the proposed model outperforms state-of-the-art sparse representation-based models and the block-matching and 3D filtering algorithm in terms of denoising performance and the computational efficiency.      

Laplacian sparse dictionary learning for image classification based on sparse representation

Sparse representation is a mathematical model for data representation that has proved to be a powerful tool for solving problems in various fields such as pattern recognition, machine learning, and computer vision. As one of the building blocks of the sparse representation method, dictionary learning plays an important role in the minimization of the reconstruction error between the original signal and its sparse representation in the space of the learned dictionary. Although using training samples directly as dictionary bases can achieve good performance, the main drawback of this method is that it may result in a very large and inefficient dictionary due to noisy training instances. To obtain a smaller and more representative dictionary, in this paper, we propose an approach called Laplacian sparse dictionary (LSD) learning. Our method is based on manifold learning and double sparsity. We incorporate the Laplacian weighted graph in the sparse representation model and impose the l₁-norm sparsity on the dictionary. An LSD is a sparse overcomplete dictionary that can preserve the intrinsic structure of the data and learn a smaller dictionary for each class. The learned LSD can be easily integrated into a classification framework based on sparse representation. We compare the proposed method with other methods using three benchmark-controlled face image databases, Extended Yale B, ORL, and AR, and one uncontrolled person image dataset, i-LIDS-MA. Results show the advantages of the proposed LSD algorithm over state-of-the-art sparse representation based classification methods.     

鲁棒可预测判别字典学习人脸识别方法

提出一种可预测判别K-SVD网络模型(DKSVDN)并用于人脸识别问题。该模型构造了一种新颖的字典结构,包含类别标签字典和描述字典,以兼顾判别和重构性能。相应的稀疏编码向量由标签编码向量和描述编码向量组成。针对样本稀疏编码时间效率低的问题,利用预测神经网络与判别字典学习模型协同训练的方法来加速预测稀疏编码。此外,针对DKSVDN还特别引入一种拟梦境的训练方法用于提升模型在训练集多样性不足时的鲁棒性。通过在主流人脸数据集上的对比实验证明了该模型的优良性能。     

分层树结构字典编码的行为识别

目的 基于学习字典的稀疏编码能够自适应地表示信号。然而,传统学习字典的原子之间缺少关联,信号的相似性在编码后缺失。考虑到结构化稀疏表示的鲁棒性和判别性能力,结构化字典的构建成为一个重要的任务。方法 依据标准的凸优化字典学习算法,引入数据点编码路径的约束（由上层原子激活的索引规划下层的索引）,构思了一种树结构字典学习框架。结果 实验结果表明,局部描述符的稀疏表示具有较好的鲁棒性和判别性,同时在KTH数据库上人体行为识别实验与其他类似文献方法相比获得了较高的识别精度,其中,时空梯度方向直方图（HOG3D）的编码识别结果达到97.99%。结论 通过实验结果,观察到采用本文构建的字典编码信号具有较好的鲁棒性和判别性,更好的适合分类任务。     

改进稀疏表示算法在人脸识别中的应用

人脸识别的主要难度在于，受到光照变化、表情变化以及遮挡的影响，会使得采集的不同人的人脸图像具有相似性。为有效解决基于稀疏表示的分类算法（Sparse Representation-based Classification，SRC）在人脸训练样本不足时会导致识别率降低和稀疏表示求解效率较低的问题，提出了基于判别性低秩分解与快速稀疏表示分类（Low Rank Recovery Fast Sparse Representation-based Classification，LRR_FSRC）的人脸识别算法。利用低秩分解理论得到低秩恢复字典以及稀疏误差字典，结合低秩分解和结构不相干理论，训练出判别性低秩类字典和稀疏误差字典，并把它们结合作为测试时所用的字典；用坐标下降法来求解稀疏系数以提高了计算效率；根据重构误差实现测试样本的分类。在YALE和ORL数据库上的实验结果表明，提出的基于LRR_FSRC的人脸识别方法具有较高的识别率和计算效率。     

Source cell phone verification from speech recordings using sparse representation

Source recording device recognition is an important emerging research field in digital media forensics. The literature has mainly focused on the source recording device identification problem, whereas few studies have focused on the source recording device verification problem. Sparse representation based classification methods have shown promise for many applications. This paper proposes a source cell phone verification scheme based on sparse representation. It can be further divided into three schemes which utilize exemplar dictionary, unsupervised learned dictionary and supervised learned dictionary respectively. Specifically, the discriminative dictionary learned by supervised learning algorithm, which considers the representational and discriminative power simultaneously compared to the unsupervised learning algorithm, is utilized to further improve the performances of verification systems based on sparse representation. Gaussian supervectors (GSVs) based on MFCCs, which have shown to be effective in capturing the intrinsic characteristics of recording devices, are utilized for constructing and learning dictionary. SCUTPHONE, which is a corpus of speech recordings from 15 cell phones, is presented. Evaluation experiments are conducted on three corpora of speech recordings from cell phones and demonstrate the effectiveness of the proposed methods for cell phone verification. In addition, the influences of number of target examples in the exemplar dictionary and size of the unsupervised learned dictionary on source cell phone verification performance are also analyzed.     

一种用于机械故障特征提取的多尺度稀疏滤波网络

针对传统稀疏滤波网络缺乏多尺度特征提取能力,难以充分挖掘故障信息的问题,提出一种多尺度稀疏滤波网络.该网络包括5层:多尺度粗粒度层,以获取多尺度信号;样本分段层,对每个尺度的信号分段;局部特征提取层,计算每个片段的特征向量;特征平均化层,将单个尺度下所有片段的特征向量池化以得到输入信号在该尺度下的表征;特征堆叠层,将所...     

Multi-polarimetric SAR image compression based on sparse representation

The use of sparse representation in signal and image processing has gradually increased over the past few years.Obtaining an over-complete dictionary from a set of signals allows us to represent these signals as a sparse linear combination of dictionary atoms.By considering the relativity among the multi-polarimetric synthetic aperture radar(SAR)images,a new compression scheme for multi-polarimetric SAR image based sparse representation is proposed.The multilevel dictionary is learned iteratively in the 9/7 wavelet domain using a single channel SAR image,and the other channels are compressed by sparse approximation,also in the 9/7 wavelet domain,followed by entropy coding of the sparse coefficients.The experimental results are compared with two state-of-the-art compression methods:SPIHT(set partitioning in hierarchical trees)and JPEG2000.Because of the efficiency of the coding scheme,our method outperforms both SPIHT and JPEG2000 in terms of peak signal-to-noise ratio(PSNR)and edge preservation index(EPI).     

Collaborative representation analysis methods for feature extraction

Recently, sparse representation (SR) theory gets much success in the fields of pattern recognition and machine learning. Many researchers use SR to design classification methods and dictionary learning via reconstruction residual. It was shown that collaborative representation (CR) is the key part in sparse representation-based classification (SRC) and collaborative representation-based classification (CRC). Both SRC and CRC are good classification methods. Here, we give a collaborative representation analysis (CRA) method for feature extraction. Not like SRC-/CRC-based methods (e.g., SPP and CRP), CRA could directly extract the features like PCA and LDA. Further, a Kernel CRA (KCRA) is developed via kernel tricks. The experimental results on FERET and AR face databases show that CRA and KCRA are two effective feature extraction methods and could get good performance.

     

自适应加权特征字典与联合稀疏相结合的遥感目标检测

随着分辨率的提高,遥感图像空间包含的有用信息越来越丰富,这使得遥感数据的处理变得更加复杂,容易发生维数灾难并影响识别效果。针对这一情况,提出一种自适应加权特征字典与联合稀疏相结合的遥感图像目标检测方法(GJ-SRC)。首先将训练图像和待测图像进行Gabor变换以提取特征图像。然后计算各个特征值在进行稀疏表示时的贡献权重,通过自适应方法构造特征字典,使字典具有更强的判别能力。最后,提取每一类图像的公共特征和单个图像的私有特征构成联合字典,并利用测试图像稀疏表示进行目标检测识别。为了避免Gabor变换产生的维数灾难,在处理过程中采用PCA方法对特征字典进行降维,以降低计算成本。实验表明,与现有的SRC方法和遥感目标检测方法等相比,所提方法具有较好的检测效果。