Semi-fragile Watermarking For Image Authentication And Recovery Based On Digital Hologram

With the development of networks and the widely used of personal computers,the application of digital multimedia data (image, audio, video) has been more and more popular. With the advent of versatile digital multimedia processing tools, multimedia data can be easily copied and manipulated. On the other hand, the availability of such powerful tools has also provided an opportunity for illegal to copy, the redistribution and various malicious attacks. Then how to verify the authentication and integrity verification of digital multimedia products has become an urgent problem to be solved. Digital watermarking, especially semi-fragile watermarking as one approach to ensure the security of multimedia plays an important role in copyright protection, authentication and integrity verification of digital multimedia products and has become a popular research area recently.Already existed semi-watermarking algorithms have a good development in robustness of watermark and tamper localization, but there are still some problems. For example, some watermarking algorithms are sensitive to joint strike and can’t effectively discriminate occasional attacks and malicious attacks, some recovery watermarking schemes for image are ineffective. In addition, there are some other problems for instance the security of watermark, the embedding capacity, the invisibility of watermarking.In view of the above problems, this paper studied the semi-fragile watermarking algorithms for image based watermarking tamper detection and recovery scheme. The main works are as follows:Firstly, this section researches the hologram watermarking algorithms in the application of images as well as the semi-fragile watermarking algorithms based SVD, then proposed a watermarking algorithm for image authentication based digital fresnel hologram. According to that the robustness of hologram watermark is stronger than the general watermark against conventional image processing, the algorithm employs a fresnel hologram as the watermark and embed it in the the singular value matrix vector (SVD) in wavelet domain of image by the help of Human Visual Systerme (HVS). The results show that the algorithm is robust to occasional manipulations such as Gaussian noise, JPEG compression, vulnerability to malicious manipulations and the watermarked image still perserves high image quality after the embedding of the watermark.Secondly, this section researches the wavelet transformation based watermarking tamper detection and recovery scheme and designs a semi-fragile watermarking algorithm for image authentication and recovery based on digital hologram, the watermarking-based authentication scheme extracts the single value in low-frequency band image as the authentication watermark and extracts the image feature from the low frequency domain as the recoverable watermark, the authentication watermark uses the high sensitivity on initial value of chaotic mapping to generate two encrypted watermark, one watermark would need to encrypted by hash (MD5) algorithm to generate the final embedded watermark, the authentication watermarks are embedded into wavelet domain by modifying coefficents of the vertical and the horizontal detail subbands of image sub-blocks, the recoverable watermark is generated digital fresnel hologram and embedded it into its owen LSB of image. Experimental simulation shows that the proposed scheme is perfecteffect in capacity, security, tamper localization and image recovery, the algorithm obtains better performance in distinguishing from malicious and non-malicious manipulations well.