DCT结合特征选择的红外人脸识别

为了从生物特征和统计角度来提高识别的性能,提出了一种基于血流图的离散余弦变换（discrete cosine transform,DCT）与特征选择相结合的人脸识别方法。该方法首先利用血流模型把红外温谱图转换成血流图,得到更具丰富频率的特征。其次,采用DCT变换可以有效地消除血流图的相关性。最后,在DCT域特征提取阶段,为了提高特征提取的有效性,特征选择和子空间学习基于一致的可分性目标：特征选择引入基于可分性的DCT系数选择算法以抽取鉴别能力强的DCT系数,对抽取的DCT系数采用基于可分性的线性鉴别分析（linear discriminant analysis,LDA）方法。实验结果表明,该红外人脸识别方法可以快速有效地提取血流图中适合分类的特征,识别率优于传统DCT＋LDA方法。     

融合判别式深度特征学习的图像识别算法

目的 卷积神经网络在图像识别算法中得到了广泛应用。针对传统卷积神经网络学习到的特征缺少更有效的鉴别能力而导致图像识别性能不佳等问题,提出一种融合线性判别式思想的损失函数LDloss（linear discriminant loss）并用于图像识别中的深度特征提取,以提高特征的鉴别能力,进而改善图像识别性能。方法 首先利用卷积神经网络搭建特征提取所需的深度网络,然后在考虑样本分类误差最小化的基础上,对于图像多分类问题,引入LDA（linear discriminant analysis）思想构建新的损失函数参与卷积神经网络的训练,来最小化类内特征距离和最大化类间特征距离,以提高特征的鉴别能力,从而进一步提高图像识别性能,分析表明,本文算法可以获得更有助于样本分类的特征。其中,学习过程中采用均值分批迭代更新的策略实现样本均值平稳更新。结果 该算法在MNIST数据集和CK+数据库上分别取得了99.53%和94.73%的平均识别率,与现有算法相比较有一定的提升。同时,与传统的损失函数Softmax loss和Hinge loss对比,采用LDloss的深度网络在MNIST数据集上分别提升了0.2%和0.3%,在CK+数据库上分别提升了9.21%和24.28%。结论 本文提出一种新的融合判别式深度特征学习算法,该算法能有效地提高深度网络的可鉴别能力,从而提高图像识别精度,并且在测试阶段,与Softmax loss相比也不需要额外的计算量。     

Joint spectral-spatial hyperspectral image classification based on hierarchical subspace switch ensemble learning algorithm

In this paper, a novel spectral-spatial hyperspectral image classification method has been proposed by designing hierarchical subspace switch ensemble learning algorithm. First, the hyperspectral images are processed by fast bilateral filtering to get the spatial features. The spectral features and spatial features are combined to form the initial feature set. Second, Hierarchical instance learning based on iterative means clustering method is designed to obtain hierarchical instance space. Third, random subspace method (RSM) is used for sampling the features and samples, thereby forming multiple sub sample set. After that, semi-supervised learning (S²L) is applied to choose test samples for improving classification performance without touching the class labels. Then, micro noise linear dimension reduction (mNLDR) is used for dimension reduction. Afterwards, ensemble multiple kernels SVM(EMK_SVM) are used for stable classification results. Finally, final classification results are obtained by combining classification results with voting strategy. Experimental results on real hyperspectral scenes demonstrate that the proposed method can effectively improve the classification performance apparently.     

A linear feature extraction for multiclass classification problems based on class mean and covariance discriminant information

A parametric linear feature extraction method is proposed for multiclass classification. The skeleton of the proposed method consists of two types of schemes that are complementary to each other with regard to the discriminant information used. The approximate pairwise accuracy criterion (aPAC) and the common-mean feature extraction (CMFE) are chosen to exploit the discriminant information about class mean and about class covariance, respectively. Choosing aPAC rather than the linear discriminant analysis (LDA) can also resolve the problem of overemphasized large distances introduced by LDA, while maintaining other decent properties of LDA. To alleviate the suboptimum problem caused by a direct cascading of the two different types of schemes, there should be a mechanism for sorting and merging features based on their effectiveness. Usage of a sample-based classification error estimation for evaluation of effectiveness of features usually costs a lot of computational time. Therefore, we develop a fast spanning-tree-based parametric classification accuracy estimator as an intermediary for the aPAC and CMFE combination. The entire framework is parametric-based. This avoids paying a costly price in computation, which normally happens to the sample-based approach. Our experiments have shown that the proposed method can achieve a satisfactory performance on real data as well as simulated data.     

GLCM和DWT特征在打印文件机源认证中的应用

为了有效解决打印文件机源认证问题,提出了一种基于统计纹理特征选择的打印文件机源认证方法。综合考虑打印字符图像的空间域和时频域特性,将GLCM和DWT统计纹理特征进行组合,运用ReliefF算法实现组合特征的初选,二次特征选择使用SVM-RFE算法。文中实验结果表明,在英文相同字有重复样本集和中文不同字无重复样本集上的分类准确率分别为95.20%和75.00%;特征组合与特征选择有利于提高打印文件机源认证的分类鉴别性能。     

A method of combining multiple probabilistic classifiers through soft competition on different feature sets

A novel method is proposed for combining multiple probabilistic classifiers on different feature sets. In order to achieve the improved classification performance, a generalized finite mixture model is proposed as a linear combination scheme and implemented based on radial basis function networks. In the linear combination scheme, soft competition on different feature sets is adopted as an automatic feature rank mechanism so that different feature sets can be always simultaneously used in an optimal way to determine linear combination weights. For training the linear combination scheme, a learning algorithm is developed based on Expectation–Maximization (EM) algorithm. The proposed method has been applied to a typical real-world problem, viz., speaker identification, in which different feature sets often need consideration simultaneously for robustness. Simulation results show that the proposed method yields good performance in speaker identification.     

随机选择全局多样化细粒度图像分类

针对细粒度图像分类任务中潜在的可区分特征太过细微难以捕捉、忽视不同特征间的关系等问题,提出一种随机选择全局多样化分类网络模型.首先,尝试以ConvNeXt作为主干来提升分类性能,并设计随机消除增强选择策略(REBS),通过特征消除分支和特征增强分支相互作用,促进网络学习更多相关信息,捕获潜在的可区分特征;然后,提出全局多样化模块(GDM),对不同层次的特征图进行交互建模,提高网络对比线索的能力;最后,建立内标压印数据集,将细粒度算法应用于真伪鉴定工作,实现细粒度图像分类任务在自然场景下的实际应用.所提出方法在CUB-200-2011、Stanford Cars和FGVC-Aircraft三个公开数据集上分别达到了91.9%、93.8%和93.5%的准确率,相比其他先进对比方法性能有较大幅度提升.在自建的内标压印数据集上达到了96.8%的准确率,能够实现真伪图像的准确分类.     

融合LLE与LDA特征的人脸识别方法

为更好提取识别的人脸特征,文章将非线性流形学习方法LLE提取的局部非线性特征与监督学习方法LDA提取的全局线性特征相结合,利用特征融合的思想,得出有利特征,进行人脸识别。经实验证明,该方法能显著提高人脸识别系统的性能。     

基于子空间学习的图稀疏属性选择算法*

针对处理高维度属性的大数据的属性约减方法进行了研究。发现属性选择和子空间学习是属性约简的两种常见方法,其中属性选择具有很好的解释性,子空间学习的分类效果优于属性选择。而往往这两种方法是各自独立进行应用。为此,提出了综合这两种属性约简方法,设计出新的属性选择方法。即利用子空间学习的两种技术(即线性判别分析(LDA)和局部保持投影(LPP)),考虑数据的全局特性和局部特性,同时设置稀疏正则化因子实现属性选择。基于分类准确率、方差和变异系数等评价指标的实验结果比较,表明该算法相比其它对比算法,能更有效的选取判别属性,并能取得很好的分类效果。     

基于深度卷积神经网络的脑电信号情感识别

为了点对点自动学习脑电信号（Electroencephalogram,EEG）空间与时间维度上的情感相关特征,提高脑电信号情感识别的准确率,基于DEAP数据集中EEG信号的时域、频域特征及其组合特征,提出一种基于卷积神经网络（Convolution Neural Network,CNN）模型的EEG情感特征学习与分类算法。采用包括集成决策树、支持向量机、线性判别分析和贝叶斯线性判别分析算法在内的浅层机器学习模型与CNN深度学习模型对DEAP数据集进行效价和唤醒度两个维度上的情感分类实验。实验结果表明,在效价和唤醒度两个维度上,深度CNN模型在时域和频域组合特征上均取得了目前最好的两类识别性能,在效价维度上比最佳的传统分类器集成决策树模型提高了3.58%,在唤醒度上比集成决策树模型的最好性能提高了3.29%。     

Feature selection in single and ensemble learning‐based bankruptcy prediction models

Feature selection is an important data preprocessing step for the construction of an effective bankruptcy prediction model. The prediction performance can be affected by the employed feature selection and classification techniques. However, there have been very few studies of bankruptcy prediction that identify the best combination of feature selection and classification techniques. In this study, two types of feature selection methods, including filter‐ and wrapper‐based methods, are considered, and two types of classification techniques, including statistical and machine learning techniques, are employed in the development of the prediction methods. In addition, bagging and boosting ensemble classifiers are also constructed for comparison. The experimental results based on three related datasets that contain different numbers of input features show that the genetic algorithm as the wrapper‐based feature selection method performs better than the filter‐based one by information gain. It is also shown that the lowest prediction error rates for the three datasets are provided by combining the genetic algorithm with the naïve Bayes and support vector machine classifiers without bagging and boosting.     

The application of hybrid feature based on local mean decomposition for motor imagery electroencephalogram signal classification

This paper proposed a hybrid feature extraction algorithm based on local mean decomposition (LMD), which has better solved the existing problems of low classification performance and adaptability limitation. LMD is employed to decompose the electroencephalogram (EEG) signal into multiple components, and then, the hybrid features based on instantaneous energy, fuzzy entropy, and mathematical morphological features are extracted on specific components, and the optimal feature combination is selected by analysis of variance (ANOVA). Finally, the classification result is output by the linear discriminant analysis (LDA) classifier. The results show that the maximum accuracy of the subjects in Data Set III of BCI-II by the method in this paper is 92.14%, and the maximum mutual information value is 0.8. The number of novel features used in this paper is small, and the complexity of the algorithm is reduced. It can adaptively select effective features according to individual differences and has good robustness.     

城管案件短文本特征生成与选择方法及其应用

以智慧城市管理应用系统中的案件上报短文本为对象,研究有效的特征生成和特征选择方法,实现案件快速准确地自动分类。根据案件描述短文本的特点,提出一种互邻特征组合算法,以生成描述力更强的组合特征;为进一步约减特征并优化特征空间,提出一种新的隶属度函数来为分类体系中的每个类别构建一个类别特征域,然后利用类别特征域进一步优化选择原始特征与组合特征,最终得到对分类贡献最高的特征表示集合。以南宁市青秀区“城管通”App中的案例分类为实例,验证提出的特征生成及选择方法,实验表明相对于文档频率、互信息和信息增益,提出的方法对案件分类的准确率更高,引入组合特征能显著提升分类准确率。     

基于特征加权的高光谱图像融合分类

在对高光谱图像监督分类中, 传统的监督学习方法对高光谱数据进行分类时需要获取足够的有标记样本作为训练样本, 这样可以有效的避免Hughes效应. 实际情况下的高光谱数据拥有较多的波段和相对较小的训练样本集给传统的遥感图像分类方法带来了挑战. 因此, 提出了一种基于特征组合以及特征加权的高光谱图像分类算法, 针对纹理特征分析难度较大的现实, 利用一阶直方图的统计特征描述图像纹理特征, 通过类内散度矩阵的逆矩阵作为特征加权矩阵构造组合核函数将高光谱光谱特征和空间特征融合起来, 同时利用特征加权的方法用于提高小训练样本的监督分类精度. 实验结果表明, 本文所提的方法对小样本的高光谱数据分类具有良好的效果.     

基于语义的档案数据智能分类方法研究

随着信息技术的高速发展,各种数字档案数据量出现了爆炸式的增长。如何合理地挖掘分析档案数据,提升对新收录档案智能管理的效果已成为一个亟需解决的问题。现有的档案数据分类方法是面向管理需求的人工分类,这种人工分类的方式效率低下,忽略了档案固有的内容信息。此外,对于档案信息发现和利用来说,需进一步挖掘分析档案数据内容之间的关联性。面向档案智能管理的需求,从档案数据的文本内容角度出发,对人工分类的档案进行进一步分析。采用LDA模型提取文档的主题特征向量,进而用[K]-means算法对档案的主题特征进行聚类,得到档案间的关联。针对新收录档案数据的分类问题,采用现有档案数据,有监督的训练FastText深度学习模型,用训练完成的模型对新收录的档案数据进行全自动分类。在数据集上测试的结果表明,所提聚类方法在文档数据集的准确率相较于传统的基于TF-IDF特征的聚类算法提升6%,基于FastText的档案分类方法准确率超过96%,达到了代替手工分类的级别,验证了该方法的有效性和实用性。     

基于属性自表达的低秩超图属性选择算法*

针对高维数据具有低秩形式和属性冗余等特点,提出一种基于属性自表达的无监督超图属性选择算法。具体地,该算法首先利用属性自表达特点用其他属性稀疏地表达每个属性,此自表达形式使用低秩假设寻找高维数据的低秩表示,然后建立超图正则化因子保持高维数据的局部结构,最后利用稀疏正则化因子进行属性选择。属性自表达特性确定属性的重要性,低秩表示相当于考虑数据的全局信息进行子空间学习,超图正则化因子考虑数据的局部结构对数据进行子空间学习。该算法实际上考虑数据全局和局部信息进行子空间学习,更是一种嵌入了子空间学习的属性选择算法。实验结果表明,该算法相比其它对比算法,能更有效地选取属性,并能取得很好的分类效果。     

Optimised deep learning features for improved melanoma detection

In this article, we are addressing the question of effective usage of the feature set extracted from deep learning models pre-trained on ImageNet. Exploring this option will offer very fast and attractive alternative to transfer learning strategies. The traditional task of skin lesion recognition consists of several stages, where the automated system is typically trained on preprocessed images with known diagnosis, which allows classification of new samples to predefined categories. For this task, we are proposing here an improved melanoma detection method based on the combination of linear discriminant analysis (LDA) and the features extracted from the deep learning approach. We are examining the usage of the LDA approach on activation of the fully-connected layer of deep learning in order to increase the classification accuracy and at the same time to reduce the feature space dimensionality. We tested our method on five different classifiers and evaluated results using various metrics. The presented comparison demonstrates the very high effectiveness of the suggested feature reduction, which leads not only to the significant lowering of employed features but also to the increasing performance of all tested classifiers in almost all measured characteristics.

     

缺失标记下基于类属属性的多标记特征选择

多标记特征选择已在图像分类、疾病诊断等领域得到广泛应用;然而,现实中数据的标记空间往往存在部分标记缺失的问题,这破坏了标记间的结构性和关联性,使得学习算法难以准确地选择重要特征。针对此问题,提出一种缺失标记下基于类属属性的多标记特征选择（MFSLML）算法。首先,通过利用稀疏学习方法获取每个类标记的类属属性;同时基于线性回归模型构建类属属性与标记的映射关系,以用于恢复缺失标记;最后,选取7组数据集以及4个评价指标进行实验。实验结果表明：相比基于最大依赖度和最小冗余度的多标记特征选择算法（MDMR）和基于特征交互的多标记特征选择算法（MFML）等一些先进的多标记特征选择算法,MFSLML在平均查准率指标上能够提升4.61~5.5个百分点,由此可见MFSLML具有更优的分类性能。     

一种基于特征选择的不平衡数据分类算法

不平衡数据分类是当前机器学习的研究热点,传统分类算法通常基于数据集平衡状态的前提,不能直接应用于不平衡数据的分类学习.针对不平衡数据分类问题,文章提出一种基于特征选择的改进不平衡分类提升算法,从数据集的不同类型属性来权衡对少数类样本的重要性,筛选出对有效预测分类出少数类样本更意义的属性,同时也起到了约减数据维度的目的.然后结合不平衡分类算法使数据达到平衡状态,最后针对原始算法错分样本权值增长过快问题提出新的改进方案,有效抑制权值的增长速度.实验结果表明,该算法能有效提高不平衡数据的分类性能,尤其是少数类的分类性能.     

CAT-RFE:点击欺诈的集成检测框架

点击欺诈是近年来最常见的网络犯罪手段之一,互联网广告行业每年都会因点击欺诈而遭受巨大损失。为了能够在海量点击中有效地检测欺诈点击,构建了多种充分结合广告点击与时间属性关系的特征,并提出了一种点击欺诈检测的集成学习框架——CAT-RFE集成学习框架。CAT-RFE集成学习框架包含3个部分:基分类器、递归特征消除(RFE,recursive feature elimination)和voting集成学习。其中,将适用于类别特征的梯度提升模型——CatBoost(categorical boosting)作为基分类器;RFE是基于贪心策略的特征选择方法,可在多组特征中选出较好的特征组合;Voting集成学习是采用投票的方式将多个基分类器的结果进行组合的学习方法。该框架通过CatBoost和RFE在特征空间中获取多组较优的特征组合,再在这些特征组合下的训练结果通过voting进行集成,获得集成的点击欺诈检测结果。该框架采用了相同的基分类器和集成学习方法,不仅克服了差异较大的分类器相互制约而导致集成结果不理想的问题,也克服了RFE在选择特征时容易陷入局部最优解的问题,具备更好的检测能力。在实际互联网点击欺诈数据集上的性能评估和对比实验结果显示,CAT-RFE集成学习框架的点击欺诈检测能力超过了CatBoost模型、CatBoost和RFE组合的模型以及其他机器学习模型,证明该框架具备良好的竞争力。该框架为互联网广告点击欺诈检测提供一种可行的解决方案。