Research On Digital Watermarking For Copyright Protection And Text Authentication

In recent years, along with the rapid development of multimedia technologies and networking, the copyright protection and content authentication of digital product have been paid more and more attention. As the unique superiority in digital content protection, digital watermarking has become the hot research point in this field.As to the problems existed in image copyright protection, based on the high embedding capacity and robustness, a new spread spectrum watermarking algorithm is proposed in this paper, which takes the wavelet basis sequence as the spread spectrum code. The significant watermark is embedded into wavelet coefficient blocks after being spread. With the multilevel sequence which obtained by discretizing the strictly orthogonal wavelet basis and the texture and luminance masking characteristic of human visual system, the invisibility, robustness and identification of watermark are greatly enhanced in this algorithm, also the watermark is adaptive to the host image. The simulation proves that the multilevel sequence performs better than binary sequence in attack-resistance.Against the problems existed in content authentication of binary text image, an algorithm is designed, in which the flipped pixel can be chosen adaptively. The information extraction is unrelated to the specific "embeddable" and doesn't require host image. This algorithm ensures the high embedding capacity and good invisibility, and tampering detection probability is enhanced in the meanwhile.