Digital Watermark Technologies For Images

Following the sharply development of the internet, it is more and more easy to get some digital multimedia information. However, it also causes some problems, such as copyright protection and information encryption, which become more urgency day by day. Therefore, many scholars are attracted by the multimedia information security problem. In this thesis, the author studies one of its branch-digital watermarking of images. First, some basic conceptions, specialties and application domains of it are introduced. Second, the pretreatment of digital watermarking data is discussed one by one, and their shortcomings and excellence are also pointed out. Third, many kinds of embedding technology of digital watermarking data is analyzed carefully, and some kinds of attacks arc introduced.The author also experiences a DCT domain watermarking. For the method's performance evaluation, we sharpen, filter, enlarge and shrink the image, add chirp and so on, to detect whether the image robustness of the watermark which is embedded by this scheme.Finally, the author gives out some suggests on the possible research directions in the future.