Research On Reversible Digital Watermark Technique

How to protect the information being transferred through the network has become a stumbling block of the sustained development of network technique, especially in the security of multimedia information. The watermark with a special function is embedded into the multimedia information to protect the copyright of the original author and authenticate the integrity and authenticity of the multimedia information. The watermark technique has become one focus of researchers.In this dissertation, we firstly summarize a systematical introduction of the origin, applications, classification and the research background of information hiding and watermarking; then mainly focus our research on the digital image reversible watermarking algorithm. The valuable research fruits can be summarized as follows:(1) A reversible watermark scheme based on hash function and lossless compression technology is presented. This scheme can achieve the authentication purpose with hash code and restores the original image by retrieving the watermark sequence completely with lossless decompression.(2) A reversible watermarking scheme with the capability of self-recovery and tamper locating has been developed for gray images, which can realize the authentication for the integrality of image. By passing the authentication successfully, the original image can be restored from the watermarked image; otherwise the tampered position can be located. Furthermore, the original image can be recovered when a slight attack has been conducted.(3) A reversible watermarking scheme with more capability for self-recovery is presented. This scheme encodes the whole image with BCH coding method, and embeds these codes into original image with DE method. For correct decoding, the location map is also encoded by BCH coding method. The experimental results prove the ability of this scheme.