Research On Several Digital Image Watermark Arithmetic And Application

With the development of the multimedia and the network technology, the application of the digital product is more and more wide. The security of multimedia has becoming urgent problem. Of all the solution to the copyright protection, the watermarking technology is more effective one. Therefore, the study of this technology becomes a focus in the academic world. Digital Watermark is a method for imperceptibly embedding an identification code into multimedia for the purpose of proving ownership. The watermark is as one part of multimedia and strong enough to survive after some purchase. This dissertation has mainly studied digital watermarking without original image for still image and robust of watermarking. The main work includes the following four aspects:The original blind watermark based on correlativity has the disadvantage of small capacity and detection false. In this paper, we improve a blind watermark algorithm based on SVD. The experimental results show our algorithm has very excellent Imperceptibility, and robust to some popular attacks like JPEG compression, image noise and image cropping. The original image was not required for extracting the embedded watermarks.Analyze of digital image watermarking with rotation, scale and translation invariant. Emphasize on how to formation an RST invariant using Fourier-Mellin transform.On account of the specialty in Fourier Transform, It is hard to get stable detecting results by modify DFT coefficients. In this paper, each watermark bit is embedded into intermediate frequency term in DFT domain by quantizing the magnitude of Fourier spectrum. The embedded sequence can be extracted by checking neighbors of coefficients without resorting to the original unmarked image, and a rotation rectify before detecting could be improve the detecting veracity. Experimental results show that the watermark thus generated is robust against common Image processing and gently geometry distortion, while having much higher bit rate.It is difficulty and keystone to resist RST transform in digital watermark. One way is to formation a strong RST invariant space of image. Pseudo-Zernike is a kind of region-based shape descriptor, the magnitude of pseudo-Zernike moments has rotational invariant property and there is no information redundancy. we analyze the invariance of pseudo-Zemike moments and present an improved pseudo-Zernike moments that not only have rotation invariance, but also have scale invariance. Watermark signal is designed with pseudo-Zernike moments. The signal is added to the coverimage in the spatial domain after reconstruction process. Avoid image reconstruction and assure the image quality. The test results show that our watermark is robust to RST transform in an efficient way.