| Digital watermarking is a technique which takes advantage of the human visual perception system (HVS) and the human auditory system (HAS) characteristic and uses method of digital signal processing embedding the hidden content in the digital information, and only advanced instrumentation or reader can be used to extract. It is mainly used in digital media copyright protection, the authenticity of the identification, the network information data hidden secret communications and so on, and it plays a very important role. Therefore, digital watermarking and its key technology research have become the focus support of national and research staff.In this paper, two anti-copy digital watermarking algorithms based on the analysis of existing digital watermark technology have been proposed:(1) Digital watermarking algorithm anti-copy attack for image signature-based anti-copy attack. The original image was divided into blocks and their entropy and standard deviation were calculated. According to HVS characteristics, select some blocks with larger entropy and smaller standard deviation to embed the watermark. Selected blocks are transformed into DCT domain. The binary watermark image and the encrypted original image with chaotic encryption are embedded into the original image. The experiment results show that the algorithm has good invisibility, and it can effectively resist copy attack, it is also robust to image add noise, filtering, cropping and other image processing operations.(2) Digital watermarking algorithm based on the QIM anti-copy attack. This algorithm uses quantization index modulation(QIM) to embed watermark. The image signature of the original image and the watermark are embedded in the vector image in the low frequency coefficients of the DCT domain at the same time. The experiment results show that the algorithm maintains good quality of the original image, and it is robust to common attacks, such as the filtering, cropping, salt and pepper noise and so on. The strategy has a good effect of anti-copy attack. |
