Research Of Digital Image Watermarking Based On Wavelet Domain

With the rapid advance of Internet, digital media has become a main way to information dissemination. People can acquire a wide range of multimedia data through Internet easily. While at the same time, many multimedia information security problems emerge as side effects of the above convenience, including illegal copying, forgery, tampering, etc. Thus how to protect multimedia data from violation has become an important issue in information security field. As a main application of information hiding technique to multimedia copyright protection, the digital watermarking technique has been proposed as a viable solution to the copyright protection and authentication of multimedia data in a networked environment. Digital watermarking, which embeds some invisible information—watermark—into the original multimedia data such as image, audio, video signals etc, can authenticate the ownership or integrality of these multimedia data so as to protect the copyright. The hidden messages could be copyright information or other secret messages. Generally it demands robustness and imperceptibility.The thesis carry on the systemic comparatively research of the algorithm of digital watermarking which based wavelet domain. At first the background and the actuality of digital watermarking are introduced, dissertate the digital watermarking about the basic concept and character, generic model, attack analysis and evaluation of performance etc. Then the theory and application of wavelet transform, the principle of image permutation are introduced.Based on the analysis of the research in existence of the digital watermarking algorithm, we put forward a binary image digital watermarking algorithm which based on discrete wavelet transform. Put forward using the binary image which has special meaning as watermark information, and pretreatment the watermark with image permutation before it be embedded, in which way the watermark's security and imperceptibility was strengthened. In order to enhance the robustness of the algorithms, the paper put forward to the thought of the watermark was repeat embedding. Plentiful emulate experiments prove the algorithm assures the watermark's imperceptibility and robustness of the algorithm to familiar image process such as JEPG compression, noise contamination, cropping, etc.Finally, we review entire work and make the expectation of the direction for the future research of watermarking.