The watermarking of digital images, audio, video, and multimedia products in general has been proposed for resolving copyright ownership and verifying originality of content. This paper studies the contribution of watermarking for developing protection schemes. A general watermarking framework (GWF) is studied and the fundamental demands are listed. The watermarking algorithms, namely watermark generation, embedding, and detection, are analyzed and necessary conditions for a reliable and efficient protection are stated. Although the GWF satisfies the majority of requirements for copyright protection and content verification, there are unsolved problems inside a pure watermarking framework. Particular solutions, based on product registration and related network services, are suggested to overcome such problems.

Binary (bi-valued) digital signals, which are suitable watermarks for digital images are presented. They are generated by using chaotic dynamical systems that provide sufficient watermark complexity and controlled lowpass characteristics. Watermark detection is performed without resorting to the original image and its reliability is studied. Efficient robustness under lossy compression, lowpass filtering and other image processing can be achieved. Possible watermark detection after geometrical transformations is discussed.

Digital watermarking methods have been proposed for various purposes and especially for copyright protection of multimedia data. The digital watermark is embedded in a digital signal or an image and must be unrecognizable by unauthorized persons and detectable only by the legal copyright owner. We use toral automorphisms as chaotic 2-D integer vector generators in order to manipulate digital image watermarking. We propose also an embedding algorithm which provides robustness under filtering and compression.