Research On Perceptual Content Based Facial Image Authentication Techniques

Facial images are an important subset of digital images which have gained variousand critical applications in our society. However, many major fields such as public se-curity have been suffered threaten from the security issue of facial images brought bythe development of digital image processing techniques, which made the facial imageauthentication techniques turns to an urgently issues to be solved.The key issues of the security of facial image lie on the authenticity and integrityduring the use and the confidentiality during the transmission, the conventional methodsof authentication and encryption no longer satisfy these requirements. As a carrier ofvision information, the content of facial images is transmitted, received and evaluatedas the perceptual information which relays on the human vision perceptual system. Theimage authentication techniques should take more concern about the perceptual informa-tion transmitted by the image rather than the bit stream of the image file. So it would bean efficient approach to deal with the security issues of facial image that to define, de-scribe and extract the perceptual information of facial image, and to achieve facial imageauthentication with different pattern and granularity by use of the extracted perceptualfeatures.In this dissertation, the point of view that the facial image authentication techniquesshould focus on the"perceptual information"conveyed by the image rather than the car-rier itself is put forward by referring the principles and the characters of human visionperceptual system. Then, the expression and robust extraction methods of facial images'perceptual features are discussed. Further, two technical routers of facial image authenti-cation, the robust hashing way and the digital watermarking way, are investigated basedon the perceptual features of facial images. And the proposed algorithms achieve tamperrecovery based on the results of image authentication and tamper detection. To enhancethe security and ?exibility of facial image authentication system, a hierarchical encryp-tion algorithm is proposed.The major works of this dissertation is described as follow:Firstly, two most significant characters of human vision perceptual system, the se-lective attention machine and the hierarchical combination machine of receptive fields,and their mathematical descriptions or models are summarized and analyzed from thepoint of view of the constitute and the structure of human vision perceptual system. Then a set of perceptual features of facial image including their expressing methods andcorresponding extraction algorithms are derived. The multi-scale based perceptual pointsextraction algorithm simulates the center perceptual fields and their simple superimpos-ing. The Gabor function based structure skeleton simulates the simple cell's perceptualfield.Secondly, the facial image authentication techniques based on robust hash are inves-tigated. The typical model of image robust hash is proposed. And three robust hash algo-rithms for facial image authentication are proposed, which include the structure skeletonbased algorithm, the perceptual point based algorithm and the statistical feature basedalgorithm. The threshold based matching method and accurate matching method for au-thentication are implemented in these algorithms. The block based tamper detection isachieved in the structure skeleton based algorithm and circle section based tamper detec-tion is realized in the feature point based algorithm.Thirdly, the digital watermarking based facial image authentication techniques areinvestigated. A novel robust digital watermarking based facial image authentication al-gorithm is proposed, which brings the robust digital watermarking into the field of imageauthentication. And then a multiple watermarking authenticating algorithm is proposedwhich embed the geometrical information into the robust watermarking and localize thetamper by embedding a semi-fragile watermarking in the interest region of the image– the face region. And a semantic report message about tamper could be drawn bycombining the two part information from the robust watermarking and the semi-fragilewatermarking.Fourthly, the recovering of tampered facial image and hierarchical encryption offacial image are investigated. To enhance the security and ?exibility of facial imageauthentication system, a tamper recovering algorithm and a hierarchical encryption al-gorithm are proposed. The tamper recovering algorithm based on the integer waveletdecomposition and the multiple watermarking model achieve the detection and recoveryof facial image. And the hierarchical encryption algorithm which aims to the palette im-age uses two keys to achieve partial and complete encryption. Further, the hierarchicalencryption algorithm is combined with a public key protocol to build a secure imagetransmission system.