Research On Digital Watermark Technique

Digital watermark technique is one of the most popular research topics in the field of information hiding, Digital watermark is a brand new technique for protecting the security of multimedia information, which are processes of imperceptibly embedding secret messages into digital media such as images, text, video and audio to identify the copyright owner, so as to protect copyright.In the thesis, we first introduce the history and origin of information hiding and digital watermark techniques, and then discuss digital watermark techniques including the conception of digital watermark, the applications of digital watermark, the classification of watermark technology and basic requirement, the composing of watermark system and general theory, and the classification of watermark attacks.Based on current research, a digital watermark scheme is presented based on middle frequency by using spread spectrum principle. The watermark is a random squence of real numbers. The article also selects a digital image as watermark, utilizes the human visual characteristic, and designs an image watermark algorithm based on low frequency. The result of the experiment shows that the two watermark algorithms has perfect imperceptibility, and can successfully resist image processing operation such as JPEG lossy compression, resizing, median filtering, adding noise, cropping and rotating, so the thesis algorithms has good robustness. In the end, we discussed the development about digital watermark techniques in the future.