A Robust Algorithm On Image Digital Watermarking

With the development of the computer network and multi-media techniques, the copyright dispute problems of digital products are increasingly outstanding. As a kind of newly copyright protection technique, digital watermarking has got extensive research and applications. The core of digital watermarking technology is embedding key information to host data without affecting the normal function and obviously declining the quality of original image according to some strategy. Robustness which can be used to measure the effects of digital watermarking is one of the most important standards in watermarking field. It means that watermarking can still keep part of integrity and can be discriminated by the watermarking examine system after suffering from several kinds of accidental or intentional signal processing.The currently researches of watermarking algorithms usually limit to only one kind or one type of certain technique, and that is not easy to remove the original shortcoming of that kind of watermarking algorithm. The paper designed a watermarking algorithm which applies several kinds of watermarking techniques including DWT (Discrete Wavelet Transform), DCT (Discrete Cosine Transform) and LSB (Least Significant Bit) to one host image at the same time based on the robustness study of several kind typical watermarking algorithms. It embeds watermark information by the DCT watermarking algorithm firstly; and secondly the watermark information is redundantly embedded in spatial domain by the LSB watermarking algorithm. And this watermarking algorithm can make use of some advantages of three kind watermarking algorithms. And according to the concrete characteristics of image, the visual effect of watermarking can be effectively improved by choosing reasonable strength in consideration of human visual system.According to the experiments of attacking test and watermarking effect, the watermarking algorithm can resist several kinds of attacking operations such as image compress, noise interference, image cropping and wave filter. It also proves that better effect of robustness can be got while several kinds of watermarking technologies are applied to one watermarking system.