Abstract

The classic principal components analysis (PCA), kernel PCA (KPCA) and linear discriminant analysis (LDA) feature extraction methods evaluate the importance of components according to their covariance contribution, not considering the entropy contribution, which is important supplementary information for the covariance. To further improve the covariance-based methods such as PCA (or KPCA), this paper firstly proposed an entropy matrix to load the uncertainty information of random variables similar to the covariance matrix loading the variation information in PCA. Then an entropy-difference matrix was used as a weighting matrix for transforming the original training images. This entropy-difference weighting (EW) matrix not only made good use of the local information of the training samples, contrast to the global method of PCA, but also considered the category information similar to LDA idea. Then the EW method was integrated with PCA (or KPCA), to form new feature extracting method. The new method was used for face recognition with the nearest neighbor classifier. The experimental results based on the ORL and Yale databases showed that the proposed method with proper threshold parameters reached higher recognition rates than the usual PCA (or KPCA) methods.

Highlights

  • The new generation of personal authentication technologies based on individual biological characteristics is the core of various applications of the real or the virtual society

  • Note that in this paper, we focus on feature extraction with our entropy-difference weighting (EW) method and its combination with principal component analysis (PCA) and kernel PCA (KPCA), so we simplify the discussion about kernels and recognition methods

  • Just like the excellent recognition effect of EW-based Principal Components Analysis (EW-PCA), Figures 11–14 show that the overall recognition rates of EW-based Kernel Principal Components Analysis (EW-KPCA) with t = 67 were higher than KPCA, especially under the challenging circumstances of Program 3 and with a few remaining eigenvalues

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Summary

Introduction

The new generation of personal authentication technologies based on individual biological characteristics is the core of various applications of the real or the virtual society. Different elements (pixels) in a face image matrix play different roles for face recognition Another disadvantage of PCA is that it does not use some useful classification information in face recognition, so based on the above basic entropy matrix, we first construct a weighting entropy matrix to transform the original facial images, whose aim is to treat the important local features differently and fully use the classification information. There are only images for each subject in the ORL facial database and images for each subject in the Yale one, but for these gray face images, the possible values of each x ij are integers ranging from 0 to 255 In this case, directly computing the entropy without dividing the data will greatly affect the reliability of the results due to the sparse problem. The relaxed constraint makes it possible to accommodate measures that do not satisfy the sum-to-one constraint if log b M > 1

Specific Data Division Techniques in Treating Face Images
Experiments and Analysis
Experiments of EW Method
The Comparison between PCA and EW-PCA Experiments
The Experimental Comparison between KPCA and EW-KPCA
Findings
Conclusions and Discussion
Full Text
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