| In recent years, with the technology of Internet and computer-communication improved and popularized continuously, digital media, including digital image, digital video frequency and digital audio frequency, has been used widely. But the safety or property rights of these digital products have paid attention to. Digital watermarking is the cryptography additional ways and is a new technology, which can protect property rights and authenticate the source and integrality. A good watermarking algorithm should be satisfied with transparency and robustness. Of course, the premises are that the quality of digital products is not affected. That means the embedding watermarking should not be checked under the normal ways and should can bear some attacks, even evil attacks, for example, cutting, adding noises, compressing and so on. Color images are frequently used in the communication exchanging. There are many algorithms about color images. The article poses a practicable watermarking algorithm about color images.In the thesis, we first introduce chaotic system and sequence, specially chaotic sequences' quality is analyzed. And then, based on the good property of chaotic sequences as scrambled sequences, we propose a scrambled network of chaotic image with chaotic sequences' order-statistic. Because of the scrambled protection, it adds the safety of digital watermarking.Secondly, we introduce DCT of digital image. After comparing DCT with else alternating ways, the focal point is 2-DCT, including defining, physical meaning and embedding position.Finally, we put forward a new watermarking algorithm of color image. Weadaptively embed chaotic scrambled image in 2-DCT domain with mankind's sensitive difference in monochromatic images. Experiment results show that the proposed algorithm can trade off the conflict of transparency and robustness of invisible watermarking well and the generated watermarking withstand under common attacks very well.
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