Still Image Digital Watermarking And Information Embedding Algorithm Research

Still image digital watermarking and information embedding algorithms are studied in this thesis.In chapter 2, the algorithms embedding a watermark to identify the image are studied. Three algorithms are studied in this chapter, first a non-blind algorithm, second a blind algorithm, and third an algorithm to detect the alteration of an image.In chapter 3, an algorithm embedding bit series in image spatial domain is studied. The algorithm determines embedding strength using characters of Human Visual System, so the result image's quality is guaranteed. The algorithm utilizes the fact that nature image data is locally correlated, and uses a precede method to reduce the original image's energy, and at the same preserves the watermark information. The algorithm is discussed in detail in theory, and experiment result shows consistence with theory.In chapter 4, an algorithm embedding bit series in image wavelet transform domain is studied. The algorithm utilizes the model of Human Visual System in Wavelet domain, the quality of result image is preserved. The generalized Gaussian distribution is used to model the statistical property of image's wavelet transform coefficients, and a most-likely estimation method is proposed to extract the embedded information. The algorithm is analyzed in detail, and experiment result again shows that the distribution of image wavelet transform coefficients can be well modeled using the generalized Gaussian distribution.In the last chapter, work of the thesis is summarized, and the further research direction is discussed.