Research On Digital Watermarking Technique Of Image In Wavelet Domain

Recently, the development of multimedia storage and transmission technology, especially the popularization of the internet push the development of the digital media application. Many types of multimedia works such as image, video and music can be conveyed in a new way of network. These technologies bring people many conveniences, but they also bring us some large side effects, for example, anybody can get the original products of others easily, especially digital products such as images, music and films. Someone can copy and tamper the original works arbitrarily under disagree, as infringes the author's copyright. How to protect the copyright effectively and solve the problem of information safeties on network is an urgent subject.Under this condition, as a kind of technology to solve multimedia information security problem on network, watermarking technology comes up into being. It embeds watermarks into the digital medias, then carries out the functions such as information hiding, storing, copyright safeguarding by detecting the watermarks that can track the use of the digital medias. At present, watermarking technology becomes a kind of effective means to multimedia copyright authentication and its integrity safeguarding.This paper takes still images as example, firstly researches the urgent problems of watermarking technology, it brings present popular image process technique into watermarking technology in succession (such as DWT, MRF). The main contents are described as followed: 1 .Researches pretreatment of watermark signal.This paper analyses and researches the preprocess technology of watermark signal particularly. It brings forward chaos modulation on watermark modulating, designs a scrambling method based on affine transform in image watermark scrambled and brings BCH encoding into error code change of watermark. 2. Analyzes the choice of wavelet filter in digital watermarking by the numbers.Analyzes characters of wavelet filter, such as regularity, number of vanishing moments, support width and energy congregate degree of image's wavelet coefficient in low frequency, how to effect watermark system's robusticity. Discusses gist of choosing wavelet filter. Furthermore, discusses wavelet frequency adapted to embed watermark. 3.Put forward digital watermarking method based on wavelet transform and Markov random field(MRF).The method that is proposed in the paper brings Markov random field into digital watermarking technique. Uses MRP to model visual impression of image, obtains allowable distortion of every pixel. Taking use of allowable distortion, we can embed watermark adaptively according contents of image to improve average embedding intensity effectively. On the base of image's statistical character, we propose a blind digital watermarking method based on MRP and wavelet transform. The method of extracting watermark doesn't demand original image, runs simply and quickly and has better practicability.