The Research And Implementation Of Frequency Field Digital Watermarking Algorithm

With the development of multimedia technology and the popularity of Internet, distributing of digital products through Internet has become an important spreading way of new civilization. However, torts such as illegal copying and modifying of digital products are more and more serious because of easy copying and editing of digital products. It is urgent to protect the copyright of digital products. Digital watermarking is an effective and promising way of copyright protection that appears recently.In the article, the fundamental concept, general model, classic algorithm, research situation and development direction of watermarking are introduced firstly. Be directed to the conflict between robustness and invisible, a watermarking algorithm based on wavelet transform is proposed. In this algorithm, watermark, a disordered bi-level image, is embedded into images with multiple levels of grays by modifying the difference value between coefficients and the mean of their neighbors, the strength of watermark is adjusted adaptively according to the character of the image. The watermark is embedded strongly in the region with lots of veins and weakly in the flat area.Experimental result shows that this algorithm can adjust the strength of watermark adaptively, the watermark is robust and invisible. It is immune to the JPEG loss compression, noise, sharping, smoothing, and cutting. Besides, the algorithm is extended to color image through convert the image from RGB color space to YUV color space, watermark is embedded into all the three color factors and immune to the detaching color attack.