Watermark-based Image / Video Content Security

With the rapid development of information technology, our daily life is becoming digitalized and network-connected. It is convenient for the legal customers, whereas it provides the chance to pirates to infringe the copyright for various illegal purposes. That makes copyright protection an urgent issue to be resolved. The technique of digital watermark is being developed under this circumstance, and has been the main method of multimedia copyright protection. Digital watermarking is to embed the copyright information, according to some particular algorithm, into digital host signal, such as image, audio, video and so on. Digital watermarking is used to authenticate the copyright, which is the focus in the field of multimedia signal processing. The research and application of digital watermark will be of great value both in theory and application for copyright protection, integrity authentication, access control, broadcast monitoring, customers tracking and the like.According to different standards, digital watermark is classified in to different categories: visible watermark/ invisible watermark, image watermark/ video watermark and so on. This thesis related these points and the main contribution includes the following parts:1. Research on copy attack resisted watermarkIn some situation, the watermark of a legal marked image may be maliciously embedded in another illegal non-marked image. This is called copy attack which can create the false positive problem and ownership ambiguity. Through analyzing digital watermark and digital signature, a novel invisible watermarking method with image signature is proposed. For digital signature which can identify different images was involved, this method can resist copy attack. The simulations show the robustness of this method.Independent component analysis (ICA) stems from the famous "Cocktail Party" problem, which can separate the observation signals mixed by some mutually independent source signals blindly and effectively. Furthermore, it has been used successfully to extract the image features. In this thesis, a digital signature algorithm based on ICA which can describe the image uniquely is proposed. The simulations show that the image signature calculated by our algorithm is better for identifying different images than the current algorithms, which benefits the watermark method.2. Research on removing attack resisted watermark methodVisible watermark is good at proving the ownership of copyrighted digital products directly. The main problem that challenges the visible watermark is removal attack.To solve this problem, three kinds of schemes utilizing invisible watermark to protect visible watermark are proposed from different points of view. Moreover, these schemes are analyzed and compared, which is useful for further research in this field.3. Research on H.264 standard based watermarkPrevious video watermark methods are summarized in this section, especially the H.264 standard based video watermark. A H.264 standard based compressed video watermark method is proposed. The simulations demonstrate the validity which builds foundation of our team's research on H.264.The research history of digital watermarking is no more than two decades, but it is still in an underway phase. Consequently, there are still many issues which are worthwhile to be discussed and studied. At the last part of this thesis, the development trends and prospects of this field are proposed and analyzed.