The increasing availability and the distribution of multimedia data across the World Wide Web begs the question about the protection of intellectual property rights on multimedia data. This is particularly relevant in light of the fact that digital representations of intellectual property (e.g. images, video, audio data) as defined by the relevant national copyright laws (where they exist) are indistinguishable from their copies. The creation of copies requires only minimal effort and manipulation of existing data is also easy to accomplish.
A technical solution for the copyright protection problem is available in the form of digital watermarks which allow the embedding of an invisible and robust marking into digital data. Such markings can be used to uncover the illicit use of copyrighted data. The protected data are marked with additional information regarding the identity of the creator or the rights holder. Depending on application requirements it is also possible to embed other information such as the time of creation or the identity of the buyer inextricably into the data material. One of the basic requirements imposed upon such a technique is that the marking does not lead to a deterioration in the usability of the data, i.e. the marking must be robust as possible and must also maintain the quality of the data to be marked at a level that does not affect its usability. The latter requirement implies the requirement of invisibility (inaudible etc.) of the marking. Another requirement is the secrecy of the marking. The embedded information must be available only the creator or a third party entrusted with verification of copyright claims.