On Color Image Watermarking Algorithms In Cepstrum Domain

Digital Watermarking, as an effective means for protecting digital media information security, has already aroused people's extensive interests and attention. In our daily lives, images are one of the medium we most contact with, and color images are becoming more and more important. So this thesis focuses on color image watermarking techniques.Firstly, the origin, application of digital watermarking technique, the concepts, requirements and the present research situation of image watermarking are introduced. Cepstrum analysis, color images and other related knoledges are described in detail. Then, the appropriate color component which fits to be inserted a watermark is investigated. Finally, two color image watermarking algorithms in cepstrum domain which can be used in copyright protection are proposed and studied in depth.The first algorithm is based on 2-D cepstrum transformation. An image watermark is embedded in the 2-D cepstral coefficients of its blue chromatism component, C b, of the color host image. Simulating results indicate that the algorithm is robust to common attacks such as JPEG compression, median filtering, scaling, rotation, etc.The second algorithm, for the first time, embeds a watermark into a color image combineing wavelet analysis with cepstrum transform. The C b component of a host image is transformed with wavelet and cepstrum, and then embedded with a watermark. Simulations show that this algorithm can resist attacks such as JPEG compression, median filtering, scaling, rotation, etc. effectively.