Multiresolution digital watermarking, algorithms and implications for multimedia signals

grantor: University of TorontoThe large-scale communication of multimedia data motivates the protection of digital information against illegal duplication and manipulation. This work is concerned with the development and use of 'digital watermarking ' technology to embed copyright and authentication codes, and hidden annotations within media content. We assess the appropriateness of watermarking for certain problems, broaden its usefulness to multimedia applications, and design and test three multiresolution digital watermarking techniques. We provide a communications paradigm for watermarking which describes principles underlying effective data hiding strategies in analytic terms, and justify the performance gains of our schemes through the use of this framework. We introduce and formulate the problem of telltale tamper proofing, and develop a fragile watermarking algorithm which, unlike traditional techniques, characterizes the distortions so that intentional doctoring can be distinguished from integrity-preserving operations such as perceptual coding. Two other techniques are proposed for the problem of robust watermarking. In the first method, data fusion concepts are incorporated to provide robust security in which the original media signal is needed to extract the hidden data. The second approach, based on channel estimation theory, only requires the use of a key for watermark extraction. Each technique demonstrates improved robustness against signal distortions such as cropping, filtering, perceptual coding, and rescaling, in comparison to previously proposed methods of its class. Simulations verify our theoretical observations and demonstrate the feasibility of digital watermarking for use in multimedia standards. This work was support by the Natural Sciences and Engineering Research Council (NSERC) of Canada and by the Communications and Information Technology Ontario (CITO).Ph.D