Digital Watermarking Algorithm Research Apply To Copyright Symbol And Protection

With the rapid development and widespread use of the computer technology and network communication,each kind of digital media release through the Internet. The copyright protection issues become the community's concern. In this background,digital watermarking is developed quickly. Digital watermarking technique is embeding watermark information into multimedia datas through specific algorithm and does not affect the use value of the original data. This technique realize the purposes of copyright symbol and protection.This paper introduced the research background and the significance, the study achievements and the present situation. The basic conception and the system model of digital watermarking was presented. Then the paper studied the characteristics of the DCT transform and designed the digital watermarking algorithm apply to copyright symbol and protection. First,designed and carried out an adaptive visible watermarking algorithm based on DCT,according to the brightness feature of the original image,the pixel values of the original watermark was modified. And according to the luninance characteristic of the original image,watermark was embeded with different strength in the DCT domain. In the basis of the visible watermarking,designed and carried out an disvisible watermarking algorithm based on DCT. The algorithm taked full account of the characteristic of the human visual system,embed the watermark into the middle frequency of the original image,reached the balance of the robustness and imperceptibility. Finally the two algorithm was used in the same image,and getted the dual watermark image.The experimental results show that the visible watermark is very clear and identify the copyright,effectively preserve the details of the carrier image. It seems that removeing the visible watermarking without damaging the original image is very difficult. The disvisible watermark has good imperceptibility,and has high robustness to kinds of complex image processing,especially for the low-pass filter,blurring, sharpening,brightness and contrast enhancement etc. the two watermark is used in the same image,reached the dual purpose of copyright symbol and protection.