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Face Recognition Using New Image Representations. Zhiming Liu and Qingchuan Tao 2009 IEEE. Outline. Introduction Motivation New Image Representation Via PCA Transformation Experiments Conclusion. Introduction.
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Face Recognition Using New Image Representations Zhiming Liu and Qingchuan Tao 2009 IEEE
Outline • Introduction • Motivation • New Image Representation Via PCA Transformation • Experiments • Conclusion
Introduction • While the commonly used gray-scale image is derived from the linear combination of R, G, and B color component images, the new Image representations are derived from the Principal Component Analysis (PCA) tranform upon the hybrid configurations of different color component images.
Introduction • We propose to encode the facial information from the new image representations by using an effective Local Binary Pattern (LBP) feature extraction method, which extracts and fuses the multi-resolution LBP features.
Motivation • For color face image recognition, the RGB color space is commonly used in some methods. • As YIQ, HSV, and YCbCr transformed from the RGB space, are adopted to perform face recognition.
Motivation • First, we calculate the correlation coefficients contained between the individual components in RGB, YIQ, and YCbCr color spaces.
Motivation • Based on the within-class scatter matrix Swand the between-class scatter matrix Sbof the training database, we can evaluate the class separability by using the Fisher criterion: J4 = tr(Sb)/tr(Sw).
Motivation • Sw:類別內散佈矩陣(within-class scatter matrix ) • Sb:類別間散佈矩陣(between-class scatter matrix )
Motivation • Table II gives thecalculation results, which indicate that the color componentsG and B have the weakest power of imageclassification,at least for the FRGC training database.
New Image Representation Via PCA • We assume that , , and arecoloumn vectors:where N=mxn. • Wecan form a data matrix using all the trainingimages: • where l is the number of training images.
New Image Representation Via PCA • The covariancematrix of may be formulated as follows : • where is the expectation operator, t denotes the transposeoperation, and.
New Image Representation Via PCA • The PCA of a randomvector X factorizes the covariance matrix into thefollowing form: • where is anorthonormaleigenvectormatrixand is a diagonal eigenvalue matrix with diagonal elements indecreasing order .
New Image Representation Via PCA • Then a new image representation can be derived by projecting three color component images of an image onto :
Experiments • In particular, the training set contains 12,776 images that are either controlled or uncontrolled. • The target set has 16,028 controlled images and the query set has 8,014 uncontrolled images.
Experiments • A. Effectiveness of New Image Representations for Face Recognition • Some new image representations, such as URCrQ , URCbQ, and so on, can be generated by using the transformation derived from PCA. • Note that before transformation, in (4) are normalized to have zero mean and unit variance, respectively.
Experiments • Table III shows the face verification rates (FVR) at 0.1% false accept rate (FAR) , where only image representations with FVR beyond 60% are listed, and R, Y, and URGB are also included for comparison.
Experiments • Fig. 1 shows some color component images and the resulting new image representations by using the transform coefficients.
Experiments • Table IV show that there are strong decorrelations between UYCbQ and UYCrQ, URCrQ.
Experiments • The fused classification results are detailed in Table V, which indicates that the best performance 77.10% , can be reached by fusing UYCrQ and UYCbQ, as expected.
Experiments • B. LBP-based Face Recognition Using New Image Representation • In this section, we present an effective method to use LBP features for face recognition. • The LBP operator is defined as follows:
Experiments • After extensions, LBP can be expressed as: , where P and R mean P sampling points on a circle of radius R. • A LBP multi-resolution feature fusion is proposed as shown in Fig. 2.
Experiments • The third set of experiments evaluates face recognition performance by using the proposed multi-resolution LBP feature fusion on new image representations.
Experiments • The proposed LBP method is implemented to UYCrQ, UYCbQ, R, and Y images, and the corresponding experimental results are shown in Table VI.
Experiments • The final results are given in Table VII, which indicates that the best FVR of 83.41% at 0.1% FAR is achieved by fusing the classification outputs of UYCrQand Y images.
Experiments • Fig . 3 shows the corresponding ROC curves for the best FVR obtained by our method.
Conclusion • The experiments show the satisfactory results have been achieved by using these new images and LBP features. • The future work will be focused on seeking the more reliable criteria to choose the color component images, as well as the new learning methods to derive the color transformation.