Analysis and Experiments on Two Linear Discriminant Analysis Methods

Foley-Sammon linear discriminant analysis (FSLDA) and uncorrelated linear discriminant analysis (ULDA) are two well-known kinds of linear discriminant analysis. Both ULDA and FSLDA search the kth discriminant vector in an n-k+1 dimensional subspace, while they are subject to their respective constraints. Evidenced by strict demonstration, it is clear that in essence ULDA vectors are the covariance-orthogonal vectors of the corresponding eigen-equation. So, the algorithms for the covariance-orthogonal vectors are equivalent to the original algorithm of ULDA, which is time-consuming. Also, it is first revealed that the Fisher criterion value of each FSLDA vector must be not less than that of the corresponding ULDA vector by theory analysis. For a discriminant vector, the larger its Fisher criterion value is, the more powerful in discriminability it is. So, for FSLDA vectors, corresponding to larger Fisher criterion values is an advantage. On the other hand, in general any two feature components extracted by FSLDA vectors are statistically correlated with each other, which may make the discriminant vectors set at a disadvantageous position. In contrast to FSLDA vectors, any two feature components extracted by ULDA vectors are statistically uncorrelated with each other. Two experiments on CENPARMI handwritten numeral database and ORL database are performed. The experimental results are consistent with the theory analysis on Fisher criterion values of ULDA vectors and FSLDA vectors. The experiments also show that the equivalent algorithm of ULDA, presented in this paper, is much more efficient than the original algorithm of ULDA, as the theory analysis expects. Moreover, it appears that if there is high statistical correlation between feature components extracted by FSLDA vectors, FSLDA will not perform well, in spite of larger Fisher criterion value owned by every FSLDA vector. However, when the average correlation coefficient of feature components extracted by FSLDA vectors is at a low level, the performance of FSLDA are comparable with ULDA.

A computer aided detection framework for mammographic images using fisher linear discriminant and nearest neighbor classifier

Today, mammography is the best method for early detection of breast cancer. Radiologists failed to detect evident cancerous signs in approximately 20% of false negative mammograms. False negatives have been identified as the inability of the radiologist to detect the abnormalities due to several reasons such as poor image quality, image noise, or eye fatigue. This paper presents a framework for a computer aided detection system that integrates Principal Component Analysis (PCA), Fisher Linear Discriminant (FLD), and Nearest Neighbor Classifier (KNN) algorithms for the detection of abnormalities in mammograms. Using normal and abnormal mammograms from the MIAS database, the integrated algorithm achieved 93.06% classification accuracy. Also in this paper, we present an analysis of the integrated algorithm’s parameters and suggest selection criteria.

An Optimization Criterion for Generalized Marginal Fisher Analysis on Undersampled Problems

Marginal Fisher analysis （MFA） not only aims to maintain the original relations of neighboring data points of the same class but also wants to keep away neighboring data points of the different classes.MFA can effectively overcome the limitation of linear discriminant analysis （LDA） due to data distribution assumption and available projection directions.However,MFA confronts the undersampled problems.Generalized marginal Fisher analysis （GMFA） based on a new optimization criterion is presented,which is applicable to the undersampled problems.The solutions to the proposed criterion for GMFA are derived,which can be characterized in a closed form.Among the solutions,two specific algorithms,namely,normal MFA （NMFA） and orthogonal MFA （OMFA）,are studied,and the methods to implement NMFA and OMFA are proposed.A comparative study on the undersampled problem of face recognition is conducted to evaluate NMFA and OMFA in terms of classification accuracy,which demonstrates the effectiveness of the proposed algorithms.

DISCRIMINATIVE ANALYSIS OF FUNCTIONAL NEAR-INFRARED SPECTROSCOPY SIGNALS FOR DEVELOPMENT OF NEUROIMAGING BIOMARKERS OF ELDERLY DEPRESSION

Functional near-infrared spectroscopy(fNIRS)is a neuroimaging technology which is suitable for psychiatric patients.Several fNIRS studies have found abnormal brain activations during cognitive tasks in elderly depression.In this paper,we proposed a discriminative model of multivariate pattern classification based on fNIRS signals to distinguish elderly depressed patients from healthy controls.This model used the brain activation patterns during a verbal fluency task as features of classification.Then Pseudo-Fisher Linear Discriminant Analysis was performed on the feature space to generate discriminative model.Using leave-one-out(LOO)cross-validation,our results showed a correct classification rate of 88%.The discriminative model showed its ability to identify people with elderly depression and suggested that fNIRS may be an efficient clinical tool for diagnosis of depression.This study may provide the first step for the development of neuroimaging biomarkers based on fNIRS in psychiatric disorders.

Multispectral Imaging in Combination with Multivariate Analysis Discriminates Selenite Induced Cataractous Lenses from Healthy Lenses of Sprague-Dawley Rats

Cataracts are the leading cause of blindness worldwide. Current methods for discriminating cataractous lenses from healthy lenses of Sprague-Dawley rats during preclinical studies are based on either histopathological or clinical assessments which are weakened by subjectivity. In this work, both cataractous and healthy lens tissues of Sprague-Dawley rats were studied using multispectral imaging technique in combination with multivariate analysis. Multispectral images were captured in transmission, reflection and scattering modes. In all, five spectral bands were found to be markers for discriminating cataractous lenses from healthy lenses;470 nm and 625 nm discriminated in reflection mode whereas 435 nm, 590 nm and 700 nm discriminated in transmission mode. With Fisher’s Linear discriminant analysis, the midpoints for classifying cataractous from healthy lenses were found to be 14.718 × 10−14 and 3.2374 × 10−14 for the two spectra bands in the reflection mode and the three spectral bands in the transmission mode respectively. Images in scattering mode did not show significant discrimination. These spectral bands in reflection and transmission modes may offer potential diagnostic markers for discriminating cataractous lenses from healthy lenses thereby promising multispectral imaging applications for characterizing cataractous and healthy lenses.

Texture Analysis and Characteristic Identification About Plaque Tissues of IVUS

Intravascular ultrasound can provide clear real-time cross-sectional images,including lumen and plaque.In practice,to identify the plaques tissues in different pathological changes is very important.However,the grayscale differences of them are not so apparent.In this paper a new textural characteristic space vector was formed by the combination of Co-occurrence Matrix and fraction methods.The vector was projected to the new characteristic space after multiplied by a projective matrix which can best classify those plaques according to the Fisher linear discriminant.Then the classification was completed in the new vector space.Experimental results found that the veracity of this classification could reach up to 88%,which would be an accessorial tool for doctors to identify each plaque.

Fisher线性鉴别分析的理论研究及其应用

Fisher线性鉴别分析已成为特征抽取的最为有效的方法之一 .但是在高维、小样本情况下如何抽取Fisher最优鉴别特征仍是一个困难的、至今没有彻底解决的问题 .文中引入压缩映射和同构映射的思想 ,从理论上巧妙地解决了高维、奇异情况下最优鉴别矢量集的求解问题 ,而且该方法求解最优鉴别矢量集的全过程只需要在一个低维的变换空间内进行 ,这与传统方法相比极大地降低了计算量 .在此理论基础上 ,进一步为高维、小样本情况下的最优鉴别分析方法建立了一个通用的算法框架 ,即先作K L变换 ,再用Fisher鉴别变换作二次特征抽取 .基于该算法框架 ,提出了组合线性鉴别法 ,该方法综合利用了F S鉴别和J Y鉴别的优点 ,同时消除了二者的弱点 .在ORL标准人脸库上的试验表明 ,组合鉴别法所抽取的特征在普通的最小距离分类器和最近邻分类器下均达到 97%的正确识别率 ,而且识别结果十分稳定 .

基于YCbCr颜色空间和Fisher判别分析的棉花图像分割研究

棉花的分割是采棉机器人研究的关键技术。本文分别在HSV、HIS和YCbCr颜色空间下,首先根据棉花的颜色信息与背景颜色信息的差距,对样本图像中的各个对象(棉絮、棉枝、土壤等)分类;其次根据分类结果分别提取各类在各颜色空间下的样本像素值;再根据类间离散度最大和类内离散度最小的准则计算出Fisher判别向量和各类的质心;最后按照像素值离各质心最近的准则进行图像分割。结果表明,在YCbCr颜色空间下产生的分割噪声最小,选取此颜色空间,采用贴标签的方法自适应去噪。实验仿真表明,本方法可有效避免阳光直射和阴影的干扰,对各种情况都能准确分割,分割准确率达90.44%。

基于Fisher判别分析的贝叶斯分类器

针对满足"类条件属性相互独立"假定的经典贝叶斯分类器无法有效利用类间信息的缺陷,结合Fisher线性判别分析,给出一种基于Fisher线性判别分析的贝叶斯分类器的改进算法。该算法通过寻找类与类最大分离的投影空间,将原样本向最大分离空间投影,以获得新样本,并采用贝叶斯分类器对新样本进行分类。实验结果表明,在给定的数据集上,该贝叶斯分类器的分类正确率较高,分类性能较好。

基于Fisher线性判别分析的语音信号端点检测方法

传统的语音端点检测方法对辅音,特别是受到噪声污染的清音部分与背景噪声之间分离能力不足。针对上述问题,该文提出一种基于Fisher线性判别分析的梅尔频率倒谱系数(F-MFCC)端点检测方法。将清音信号和背景噪声视为两类分类问题,采用Fisher准则求解具有判别信息的最佳投影方向,使得投影后的特征参数具有最小类内散度和最大类间散度,从而增大清音与背景噪声的可分离性。在不同语音库上的实验结果表明,F-MFCC能够在不同信噪比和背景噪声条件下提高语音端点检测的准确率。

基于排列组合熵和加权核Fisher的肌电跌倒检测

为实现老年人的跌倒与日常行为动作的模式识别,提出了一种基于排列组合熵和加权核Fisher线性判别的表面肌电信号跌倒识别方法.以腓肠肌和股外侧肌2路肌电信号对应的排列组合熵为特征向量输入加权核Fisher线性分类器进行模式识别,对跌倒与坐下、蹲下和行走进行识别.实验结果表明,该方法的跌倒识别率为93.33%,特异度100%,优于其他分类方法.

基于二维Fisher线性判别的掌纹识别方法

在Fisher线性判别(FLD)中,类内离散矩阵总是奇异的。为了解决矩阵的奇异性问题,应用一种新的二维Fisher线性判别(2DFLD)直接进行矩阵投影。对于PolyU掌纹图像库,分别用PCA,PCA+FLD和2DFLD提取特征掌纹子空间,将待识别图像投影到低维子空间上,用余弦距离进行掌纹匹配。实验结果表明,与PCA相比,PCA+FLD的识别率最多提高1.18%。2DFLD识别率最高达到99.34%,比PCA+FLD提高7.61%,特征提取仅耗时0.047s。

基于核的Fisher极小鉴别分析及人脸识别

Fisher鉴别分析被公认为是特征抽取的有效方法之一,但由于其只能抽取线性特征,而对于实际应用中复杂的样本图像分布,抽取非线性鉴别特征显得十分必要。先前的基于核Fisher鉴别分析算法虽然解决了非线性特征抽取问题,但是其存在最终特征维数受类别数限制的问题。为了能够进一步提高特征提取效率,提出了一种基于核的Fisher极小鉴别分析方法,该方法使得最终特征维数不受类别数限制。在Yale和NUST603人脸库上进行了鉴别性能实验,实验结果验证了该方法的有效性。

Fisher大间距线性分类器

作为一种著名的特征抽取方法,Fisher线性鉴别分析的基本思想是选择使得Fisher准则函数达到最大值的向量(称为最优鉴别向量)作为最优投影方向,以便使得高维输入空间中的模式样本在该向量投影后,在类间散度达到最大的同时,类内散度最小。大间距线性分类器是寻找一个最优投影矢量(最优分隔超平面的法向量),它可使得投影后的两类样本之间的分类间距(Margin)最大。为了获得更佳的识别效果,结合Fisher线性鉴别分析和大间距分类器的优点,提出了一种新的线性投影分类算法——Fisher大间距线性分类器。该分类器的主要思想就是寻找最优投影矢量wbest(最优超平面的法向量),使得高维输入空间中的样本模式在wbest上投影后,在使类间间距达到最大的同时,使类内离散度尽可能地小。并从理论上讨论了与其他线性分类器的联系。在ORL人脸库和FERET人脸数据库上的实验结果表明,该线性投影分类算法的识别率优于其他分类器。

一种改进Fisher准则的线性鉴别分析方法

目前线性鉴别分析以Fisher准则或是逐对类加权Fisher准则为依据,但前者不能限制离群类,后者计算量大,鉴于此,提出一种改进Fisher准则用于线性鉴别分析。回顾了Fisher准则和逐对类加权Fisher准则,指出其中问题产生的根本原因。提出类距离和类离群程度的定义,以类距离为依据判定各类离群程度,以类离群程度为参数赋予各类权值,重新计算总体类均值和类间离散度矩阵,以得到限制离群类、突出常规类的改进Fisher准则。这种改进Fisher准则计算简单,能有效限制离群类。

基于核Fisher判决分析的脸谱识别新方法

本文提出一种新的基于核Fisher判决分析(简称KFDA)的脸谱识别方法。即首先应用KFDA提取脸谱特征,然后,进行脸谱识别。利用标准的AT&T脸谱数据库对KFDA特征提取方法和PCA、FDA以及ICA特征提取方法进行比较,最后使用线性支持向量机(简称SVM)进行分类和识别,实验结果显示基于KFDA特征提取脸谱识别方法的识别率明显优于其它三种脸谱识别方法的识别率。

基于图像分块的改进Fisher人脸识别算法

二维方法用于图像矩阵特征提取,虽然速度快,但影响了分类速度。针对二维线性鉴别分析(Two-Dimensional Linear Discriminant Analysis,2DLDA)的特点,研究了一种基于图像分块的改进Fisher人脸识别算法,该算法首先对人脸图像进行压缩降维处理,得到相应的特征矩阵,然后利用改进Fisher算法对特征矩阵进行类间离散度矩阵和类内离散度矩阵的计算,该算法充分考虑了类别信息,避免了传统Fisher算法造成的小样本问题,有效提高了分类速度。基于ORL(Olivetti Research Laboratory)与Yale人脸数据库的实验结果证明了该算法的有效性。

基于向量组的Fisher线性鉴别分析方法

提出了一种基于向量组的Fisher线性鉴别分析方法。该方法先将原始的高维向量分割为低维的子向量组,再对向量组运用Fisher线性鉴别分析。这种处理方法,不但能够解决任意高维下的小样本问题,而且通过选择恰当的子向量维数,可以从向量中抽取出最有效的特征值。此外,基于向量组的Fisher线性鉴别分析是Fisher线性鉴别分析和二维Fisher线性鉴别分析的进一步推广。

LLE与核Fisher判别分析结合的人脸识别研究

针对人脸识别问题提出了将LLE与核Fisher相结合的识别方法 LLEKF,先应用LLE方法将样本和待测试的人脸图像集降低到一定维数,再利用核Fisher判别法通过选择合适的核函数,确定最优参数,对降维后的样本图像进行训练,并对降维后的人脸图像进行分类。实验证明,利用LLE低维嵌入后的数据能够更好地保持原人脸数据的非线性特征,并降低特征提取的时间,再经过核Fisher进行分类,明显提高了分类的效率。

基于二维Fisher线性鉴别分析和粒子群优化的红外图像分割(英文)

二维Fisher线性鉴别分析的图像分割算法,考虑了图像中目标和背景之间类间方差和类内方差在类别分离中的作用,有效地克服经典Otsu阈值法当图像中目标的面积很小(直方图上表现为峰的大小相差很大或者没有明显双峰)时产生的阈值"漂移"现象,是一种有效的图像分割方法。针对二维Fisher线性鉴别分析计算量大的特点,采用粒子群算法来搜索最优二维阈值向量。每个粒子代表一个可行的二维阈值,通过粒子群之间的协作来获得最优阈值向量。实验结果表明,所提出的方法不仅能准确地分割图像,而且计算量大大减少,达到了快速分割的目的,便于实时应用。