Research On Digital Image Watermarking Algorithms

Digital image watermarking algorithms are one of the investigation hotspots in the digital watermarking techniques. This thesis is concerned with digital image watermarking technology. The components of a digital image watermarking system are discussed in detail. Advantages and disadvantages of various typical algorithms are analysed. Two novel image watermarking algorithms in cepstrum domain for different applications are presented, namely 1-dimension cepstrum transformation image watermarking algorithm and 2-dimension cepstrum domain spread spectrum image watermarking algorithm.The first method, used for copyright protection, demonstrates improved robustness against JPEG compression, image cropping, scaling, noising, and so on in comparison to existing algorithms. The original image is needed to extract the watermarking signal. The second approach used for traitor tracing, combines cepstrum features with spread spectrum theory. No original image but the key is required for watermarking extraction.The performance of the proposed algorithms is evaluated through extensive computer simulations using various different images. Simulation results show that the proposed algorithms are robust against most watermarking attacks such as JPEG compression, image filtering and so forth.