Design Of Image Authentication Algorithm Based On Digital Watermarking

As the Internet and communication technology has developed rapidly, and information has become abundant, increasing number of digital image via Internet to disseminate, which greatly convenience to people's use. However the information security problem, including image authentication, has been following. The image authentication based on digital watermarking is the just new technology of information security.This paper is focused on the research of digital image. At first, it introduced the basic theory of digital watermarking, including the concept, features, classification and the application of the digital watermarking. At the same time, it introduced some typical algorithms, in which wavelet transform is key content. Then it introduced the classification of certification system based on the digital watermarking. And it analyzed some basic problems in the process of image authentication. On this basis, this paper proposed two kinds of algorithms. One is based on the gray image, and the other is based on the color image:First, this paper proposed a self-embedded algorithm which can resist the JPEG compression and locate the tamper accurately. The basic principle of the scheme is decomposition the image with the wavelet transform. To get the self-embedded watermarking, the algorithm should compress the original image using SPIHT algorithm. And embedded it into the low pass, in the meantime, embedded the authentication watermark into the high pass of the wavelet coefficient. As the self-embedded watermark was embedded into the low pass, it was robust in itself, and can resist the JPEG compression. As using the authentication watermark, this algorithm not only needn't set the threshold which was to locate the tamper, but also can locate the tamper actually.Secondly, this paper proposed an authentication algorithm of color image based on the algorithm of gray image. The principle of the theme was embedded the authentication watermark into the Y part of the color image. The simulation results showed that the semi-fragile watermark can resist the signal processing, locate the tamper accurately, and even can infer the type of the tamper.