主动学习半监督聚类入侵检测算法

针对聚类的入侵检测算法误报率高的问题,提出一种主动学习半监督聚类入侵检测算法.在半监督聚类过程中应用主动学习策略,主动查询网络中未标记数据与标记数据的约束关系,利用少量的标记数据生成正确的样本模型来指导大量的未标记数据聚类,对聚类后仍未能标记的数据采用改进的K-近邻法进一步确定未标记数据的类型,实现对新攻击类型的检测.实验结果表明了算法的可行性及有效性.     

基于特征加权和非负矩阵分解的多视角聚类算法

为了在多视角聚类过程中同时考虑特征权重和数据高维性问题,提出一种基于特征加权和非负矩阵分解的多视角聚类算法(Multiview Clustering Algorithm based on Feature Weighting and Non-negative Matrix Factorization,FWNMF-MC).FWNMF-MC算法根据每个视角中每个特征在聚类过程中的重要性,自动赋予不同的权值.通过将每个视角空间中的特征矩阵分解为基矩阵与系数矩阵的乘积,将多视角数据从高维空间映射到低维空间.为了有效利用每个视角信息挖掘聚簇结构,最大化每个视角在低维空间的一致性.最后实验结果表明FWNMF-MC算法的聚类效果明显优于已有的4种有代表性的多视角聚类算法.     

基于自适应多字典学习的单幅图像超分辨率算法

自适应字典学习利用图像结构自相似性,将图像自身作为训练样本,通过字典学习使图像中的相似块在字典下具有稀疏表示形式.本文将全局字典学习中利用图像库获取附加信息的思想融入到自适应字典学习的过程中,提出了一种基于自适应多字典学习的单幅图像超分辨率算法,从低分辨率图像自身与图像库同时获取附加信息.该算法对低分辨率图像金字塔结构中的图像块进行聚类,在聚类结果的引导下将图像库中的图像块进行分类,利用各类中的样本分别构建针对各类的多个字典,从而确定表达重建图像块的最优字典.实验表明,与ScSR、SISR、NLIBP、CSSS以及mSSIM等算法相比,本文算法具有更好的超分重建效果.     

基于主动学习的图像分类技术：现状与未来

图像分类作为计算机视觉领域中的重要研究方向之一，应用领域非常广泛.基于深度学习的图像分类技术取得的成功，依赖大量的已标注数据，然而数据的标注成本往往是昂贵的.主动学习作为一种机器学习方法，旨在以尽可能少的高质量标注数据达到期望的模型性能，缓解监督学习任务中存在的标注成本高、标注信息难以大量获取的问题.主动学习图像分类算法根据样本选择策略，从未标记样本数据集合中选择出信息量丰富，对分类模型训练贡献更高的样本进行标注，以更新已标注训练数据池，如此循环直至满足给定的停止条件或模型标注预算耗尽.本文对近年来提出的主动学习图像分类算法进行了详细综述，并根据所用样本数据处理及模型优化方案，将现有算法分为三类：基于数据增强的算法，包括利用图像增广来扩充训练数据，或者根据图像特征插值后的差异性来选择高质量的训练数据；基于数据分布信息的算法，根据数据分布的特点来优化样本选择策略；优化模型预测的算法，包括优化获取和利用深度模型预测信息的方法、基于生成对抗网络和强化学习来优化预测模型的结构，以及基于Transformer结构提升模型预测性能，以确保模型预测结果的可靠性.此外，本文还对各类主动学习图像分类算法...     

基于耦合特征空间下改进字典学习的图像超分辨率重建

针对目前基于字典学习的图像超分辨率重建效果欠佳或字典训练时间过长的问题,本文提出了一种耦合特征空间下改进字典学习的图像超分辨率重建算法.该算法首先利用高斯混合模型聚类算法对训练图像块进行聚类,然后使用更改字典更新方式的改进KSVD字典学习算法来快速获得高、低分辨率特征空间下字典对和映射矩阵.重建时根据测试样本与各个类别的似然概率自适应地选择最匹配的字典对和映射矩阵进行高分辨率重建.最后利用图像非局部相似性,将其与迭代反向投影算法相结合对重建后的图像进行后处理获得最佳重建效果.实验结果表明了本文方法的有效性.     

基于WFCM算法在MRI图像分割中的应用

模糊C均值聚类(FCM)算法是一种基于非监督聚类算法。样本加权模糊C均值聚类(WFCM)算法是FCM算法的改进,该算法能够明显提高收敛速度和聚类的准确性。无论是FCM算法还是WFCM算法,对噪声都相对敏感,而且聚类数目仍然需要人工确定。在此提出一种改进算法,首先通过偏微分方程(PDE)降噪算法对原始脑MRI医学图像进行处理;其次利用聚类有效性确定最佳聚类数目,对WFCM算法进行改进;最后利用本文改进算法对图像进行聚类分割。实验表明,该方法是一种具有自动分类能力、抗噪性较好的模糊聚类图像分割算法。     

面向视角非对齐数据的多视角聚类方法

如何在视角对齐关系错位时有效进行非对齐多视角学习是一类新的挑战性问题。针对这一问题,提出面向视角非对齐数据的多视角聚类方法。一方面,为了捕获多视角异构特征的跨视角相似度信息,基于多视角非负矩阵分解进行表示学习,将原始特征嵌入一个可度量的低维同构空间。另一方面,在低维同构空间中,以二部图最优匹配模型建模视角对齐关系,并提出参考视角概念将模型推广至多视角情形。将表示学习和视角对齐关系学习整合到统一的Bi-level优化框架,使其在迭代中相互促进,进一步提高模型对视角非对齐数据的学习能力。在视角非对齐数据聚类应用上的大量实验结果表明,相比于8种先进的多视角聚类方法,所提方法在3个数据集上的多项性能指标均取得了较优的性能。     

基于改进SMOTE的不平衡数据挖掘方法研究

少类样本合成过采样技术(SMOTE)是一种新型的过采样方法,能够有效地处理不平衡数据分类问题.但SMOTE在产生合成样本的过程中,存在一定的盲目性.因此本文提出一种改进的过采样方法一自适应SMOTE,根据样本集内部分布特性,自适应调整SMOTE方法中近邻选择策略,控制合成样本的质量.算法分析和仿真结果表明,文中提出的方法在不影响计算复杂度的前提下,有效地提高了分类算法的整体分类准确率.     

一种基于邻域粗糙集特征选择的图像分类方法

在图像分类中,单一特征提取容易造成图像信息的缺失,而多特征融合则会生成大量的冗余特征,使得图像分类的准确率降低。针对上述问题,通过改进邻域粗糙集特征选择算法,使其可以处理多维的图像特征,并将该算法应用于图像分类中。利用HOG和SURF结合空间金字塔匹配模型,得到最终的图像描述;利用线性SVM类性能和鲁棒性。     

基于半监督生成对抗网络的乳腺癌图像分类

本文针对仅有少量带标签样本时如何提高大量未标 注样本分类的的鲁棒性和准确性问题,提出一种 基于改进的半监督生成对抗网络(semi-supvised generative adversarial networks,SGAN) 的乳腺癌图像分类方法。该方法在输出层使用Softmax 函数 替代 Sigmoid 函数实现多分类。首先将随机向量输入到生成网络中,生成伪样本并标记为伪样本 类进行训 练。接着将真实标签样本、真实无标签样本和伪样本输入到判别网络中,输出为不同类概率 值;然后采 用半监督训练方法反向传播更新参数;最后实现对乳腺癌病理图像的分类,标注样本数量分 别为25、 50和200,最终准 确率达到95.5%。实验结果表明,当标注 样本有限时,本文算法的准确 率具有良好 的鲁棒性。本文算法相比于使用卷积神经网络和迁移学习(tranfer learning,TL)等分类方法准确率有了显著提高。     

Multi-view representation learning for multi-view action recognition

Although multiple methods have been proposed for human action recognition, the existing multi-view approaches cannot well discover meaningful relationship among multiple action categories from different views. To handle this problem, this paper proposes an multi-view learning approach for multi-view action recognition. First, the proposed method leverages the popular visual representation method, bag-of-visual-words (BoVW)/fisher vector (FV), to represent individual videos in each view. Second, the sparse coding algorithm is utilized to transfer the low-level features of various views into the discriminative and high-level semantics space. Third, we employ the multi-task learning (MTL) approach for joint action modeling and discovery of latent relationship among different action categories. The extensive experimental results on M²I and IXMAS datasets have demonstrated the effectiveness of our proposed approach. Moreover, the experiments further demonstrate that the discovered latent relationship can benefit multi-view model learning to augment the performance of action recognition.     

3-D object recognition using 2-D views

We consider the problem of recognizing 3-D objects from 2-D images using geometric models and assuming different viewing angles and positions. Our goal is to recognize and localize instances of specific objects (i.e., model-based) in a scene. This is in contrast to category-based object recognition methods where the goal is to search for instances of objects that belong to a certain visual category (e.g., faces or cars). The key contribution of our work is improving 3-D object recognition by integrating Algebraic Functions of Views (AFoVs), a powerful framework for predicting the geometric appearance of an object due to viewpoint changes, with indexing and learning. During training, we compute the space of views that groups of object features can produce under the assumption of 3-D linear transformations, by combining a small number of reference views that contain the object features using AFoVs. Unrealistic views (e.g., due to the assumption of 3-D linear transformations) are eliminated by imposing a pair of rigidity constraints based on knowledge of the transformation between the reference views of the object. To represent the space of views that an object can produce compactly while allowing efficient hypothesis generation during recognition, we propose combining indexing with learning in two stages. In the first stage, we sample the space of views of an object sparsely and represent information about the samples using indexing. In the second stage, we build probabilistic models of shape appearance by sampling the space of views of the object densely and learning the manifold formed by the samples. Learning employs the Expectation-Maximization (EM) algorithm and takes place in a "universal," lower-dimensional, space computed through Random Projection (RP). During recognition, we extract groups of point features from the scene and we use indexing to retrieve the most feasible model groups that might have produced them (i.e., hypothesis generation). The likelihood of each hypothesis is then computed using the probabilistic models of shape appearance. Only hypotheses ranked high enough are considered for further verification with the most likely hypotheses verified first. The proposed approach has been evaluated using both artificial and real data, illustrating promising performance. We also present preliminary results illustrating extensions of the AFoVs framework to predict the intensity appearance of an object. In this context, we have built a hybrid recognition framework that exploits geometric knowledge to hypothesize the location of an object in the scene and both geometrical and intesnity information to verify the hypotheses.     

Color Correction for Multi-view Images Using Relative Luminance and Chrominance Mapping Curves

In order to capture 3D scenes, a multi-view camera consisting of two or more cameras is widely used; however, color consistency among views is not guaranteed in many situations. In this paper, we design relative mapping curves with consideration of the properties of luminance and chrominance components to improve the consistency. The input images are categorized into source and reference views. We convert their color domain to the YUV color space, and estimate coefficients in the mapping curves by analyzing correspondences between the two views. After that, we generate lookup tables and convert the color distributions of the source views. From the experimental results, we confirm that our proposed method improves the visual quality of multi-view images and reduces Euclidean distances in the CIELab color space among views.     

A novel semi-supervised canonical correlation analysis and extensions for multi-view dimensionality reduction

Canonical correlation analysis (CCA) is an efficient method for dimensionality reduction on two-view data. However, as an unsupervised learning method, CCA cannot utilize partly given label information in multi-view semi-supervised scenarios. In this paper, we propose a novel two-view semi-supervised learning method, called semi-supervised canonical correlation analysis based on label propagation (LPbSCCA). LPbSCCA incorporates a new sparse representation based label propagation algorithm to infer label information for unlabeled data. Specifically, it firstly constructs dictionaries consisting of all labeled samples; and then obtains reconstruction coefficients of unlabeled samples using sparse representation technique; at last, by combining given labels of labeled samples, estimates label information for unlabeled ones. After that, it constructs soft label matrices of all samples and probabilistic within-class scatter matrices in each view. Finally, in order to enhance discriminative power of features, it is formulated to maximize the correlations between samples of the same class from cross views, while minimizing within-class variations in the low-dimensional feature space of each view simultaneously. Furthermore, we also extend a general model called LPbSMCCA to handle data from multiple (more than two) views. Extensive experimental results from several well-known datasets demonstrate that the proposed methods can achieve better recognition performances and robustness than existing related methods.     

基于最大熵准则的多视角SAR目标分类方法

针对合成孔径雷达（Synthetic aperture radar,SAR）目标分类问题,提出基于最大熵准则的多视角方法。采用经典的图像相似度测度构建不同视角SAR图像之间的相关性矩阵,在此基础上分别计算不同视角组合条件下的非线性相关信息熵值。非线性相关信息熵值可分析多个变量之间的统计特性,熵值的大小即可反映不同变量之间的内在关联。根据最大熵的原则选择最优的视角子集,其中SAR图像具有最大的内在相关性。分类过程以联合稀疏表示为基础,对具有最大熵值的多个视角进行联合表示。联合稀疏表示模型同时处理若干稀疏表示问题,在它们具有关联的条件下具有提升重构精度的优势。根据不同视角求解得到的表示系数,按照类别分别计算对于选取多视角的重构误差,并根据误差最小的准则进行最终决策。文中方法可有效对多视角SAR图像样本进行相关性分析,并利用联合稀疏表示利用这种相关性,能够更好提高分类精度。采用MSTAR数据集对方法进行分析测试,通过与几类其他方法在多种测试条件下进行对比,结果显示了最大熵准则在多视角选取中的有效性和文中方法对SAR目标分类性能的优越性。     

Geometric and colorimetric error compensation for multi-view images

In general, excessive colorimetric and geometric errors in multi-view images induce visual fatigue to users. Various works have been proposed to reduce these errors, but conventional works have only been available for stereoscopic images while requiring cumbersome additional tasks, and often showing unstable results. In this paper, we propose an effective multi-view image refinement algorithm. The proposed algorithm analyzes such errors in multi-view images from sparse correspondences and compensates them automatically. While the conventional works transform every view to compensate geometric errors, the proposed method transforms only the source views with consideration of a reference view. Therefore this approach can be extended regardless of the number of views. In addition, we also employ uniform view intervals to provide consistent depth perception among views. We correct color inconsistency among views from the correspondences by considering importance and channel properties. Various experimental results show that the proposed algorithm outperforms conventional approaches and generates more visually comfortable multi-view images.     

联合多尺度多特征的高分遥感图像场景分类

高分辨率遥感图像地物信息丰富,但场景构成复杂,目前基于手工设计的特征提取方法不能满足复杂场景分类的需求,而非监督特征学习方法尽管能够挖掘局部图像块的本征结构,但单一种类及尺度的特征难以有效表达实际应用中复杂遥感场景特性,导致分类性能受限.针对此问题,本文提出了一种基于多尺度多特征的遥感场景分类方法.该算法首先设计了一种改进的谱聚类非监督特征（iUFL-SC）以有效表征图像块的本征结构,然后通过密集采样提取每幅遥感场景的iUFL-SC、LBP、SIFT等三种多尺度局部图像块特征,并通过视觉词袋模型（BoVW）获得场景的中层特征表达,以实现更为准确详实的特征描述,最后基于直方图交叉核的支持向量机（HIKSVM）进行分类.在UC Merced数据集以及WHU-RS19数据集上的实验结果表明本文方法可对遥感场景进行鉴别特征提取,有效提高分类性能.     

图像分类问题的几种深度学习策略

针对图像分类学习不够深入的问题,提出图像分类问题的几种深度学习策略研究。通过分析当前主流的主动深度学习图像、多标签图像和多尺度网络图像三种深度学习方法的工作原理和存在的优势与不足,探讨图像分类问题的优化学习策略。随后采用图像分类问题的几种深度学习策略实验的方式加以对比,实验结果表明,参数共享的深度学习图像分类方法不仅提高了预测速度,而且还能确保模型的准确性。     

Spatially constrained sparse coding scheme for natural scene categorization

Coding and pooling, the major two sequential procedures in sparse coding based scene categorization systems, have drawn much attention in recent years. Yet improvements have been made for coding or pooling separately, this paper proposes a spatially constrained scheme for sparse coding on both steps. Specifically, we employ the m-nearest neighbors of a local feature in the image space to improve the consistency of coding. The benefit is that similar image features will be encoded with similar codewords, which reduced the stochasticity of a conventional coding strategy. We also show that the Viola–Jones algorithm, which is well-known in face detection, can be tailored to learning receptive fields, embedding the spatially constrained information on the pooling step. Extensive experiments on the UIUC sport event, 15 natural scenes and the Caltech 101 database suggests that scene categorization performance of several popular algorithms can be ubiquitously improved by incorporating the proposed two spatially constrained sparse coding scheme.     

具备视角协同学习能力的多视角TSK型模糊系统

传统模糊系统建模方法本质上是一种单视角学习模式,面向适合多视角处理的场景时,它们通常只能将每一视角割裂开来进行独立建模,这导致其所得系统泛化性能往往不令人满意。针对此缺陷,该文探讨具备多视角学习能力的模糊系统建模方法。为此,基于经典的L2型TSK模糊系统,通过引入具备多视角学习能力的协同学习项,该文提出了核心的多视角TSK型模糊系统(MV-TSK-FS)建模方法。MV-TSK-FS不仅能有效地利用各视角不同特征构成的独立样本信息,还能充分地利用各视角间由于相互关联而存在内在信息,以最终达到提高系统泛化性能的效果。在模拟数据集与真实数据集上的实验结果验证了较之于传统单视角模糊建模方法该多视角模糊系统有着更好的泛化性和适用性。