Research Of Image Digital Watermarking Based On HVS

With the development at full speed of the multimedia technology and network technology, people obtaining to digital products is extremely fast and convenient, but how are copyright of the original creators of these digital products and economic benefits protected? Are the digital products safe and believing? Centre on this question, it is near and putting forward a kind of new effective digital products copyright protection and the new technology of security maintenance—the technology of digital watermark (Digital Watermark) in the world in a few years.Digital watermark technology is a kind of information safe practice, it includes very extensive research field such as the hide writing, encryption technology, communication theory and digital signal processing etc. Latently, the watermark is to the digital target who is protected (Such as the image, video, audio frequency, etc.) the one that imbedded can prove the information that the copyright is belonged to or can follow the tort and can be proposed and got the copyright which prove the carrier out when being necessary, what the watermark can't be separated with the carrier but also can resist general treatment to operate and attack.This dissertation has carried on research to a certainty to digital watermark technology based-on HVS.First of all, as the base of this technology, after gathering large quantity of documents and materials related to digital watermarking technology, this dissertation has induced its development origin, system model, basic feature, appliance pattern, introducing this technology from kinds of different directions, has summed up the common digital watermark algorithm for the following algorithm design.Secondly, this dissertation has introduced the human visual system (HVS) and the frequency response function of human visual sense, has introduced the discrete cosine transform (DCT) and the discrete wavelet transform (DWT), as well as the pretreatment transform of image.Then, in the frequency-domain watermarking, from the aspect of spread-spectrum theory, this dissertation has proposed a kind of scheme of digital watermark based on content characteristic of the color image in DCT. The watermark fully considers the HVS characteristic—luminosity shelter, edge shelter, and veins shelter. Firstly, it classifies the image block, then defines the coefficient of each classification, and according to the RGB (red, green, blue) rate of the block and its classification in HVS, adaptively adjusts the imbedding intensity for realizing the watermark imbedding in the biggest intensity.Afterwards, a kind of digital watermark algorithm based on lattice vector quantization in DWT is proposed. At first, it quantizes the image coefficient vector gotten from DWT with the lattice vector quantization technology, then imbeds the watermark signal into the coefficient. The results of experiments confirm that the algorithm is robust against the JPEG compression, scaling, Gaussian noise, and median filtering.Finally, summarizes my achievement of study and looks forward to the further development of the digital watermark.