Digital Images Watermarking Algorithms Based On Wavelet Transform

The information hiding technology is a new information security technology based on the great development and popularization of Internet and multimedia technology. Multimedia digital watermarking technique is a remarkable research problem in the filed of information hiding technique. After deeply analyzing the technical characters and request of information hiding, two novel fragile watermarking algorithm for complete tamper proofing of a still image is proposed from the point of application in information security.The first algorithm way put forward in this thesis is a kind of fragile watermarking method that combines together DCT-DWT to the picture. The first, look like each detail picture of direction of picture and each layers to carry on DCT towards get of again, then will imbed to look like the son diagram DCT transformation through two value watermark pictures of the false random row preface behind of the part of the high part of frequency and the detail son diagram energy concentration. This kind of choice imbeds the method of the watermark data position, making use of the picture well the characteristics of the high information of frequency and the sense of vision characteristic of the person, be advantageous to watermark's can't see the sex and flimsiness.The second calculate way then a kind of according to the image authentication of from weak and numerical watermark method of the orientation half, the watermark project adoption according to the space-frequency area analysis method of a transformation, defined an amount of coefficient to turn the function to carry out the watermark to imbed and withdraw. Designed three mentally densest key, uses to define the watermark and the position that it imbed. The quantity of the watermark turn parameter can according to defend to distort of a request to establish. Textual this kind of calculate way not only can give a position for distort and the serious degree that distort, and can is tolerant of the compression of JPEG nicely, express a certain Robust stick.The end still passed the experience method to verify the flimsiness and the Robust stick of two kinds of calculate ways, experimenting the result to express the usage this the watermark that two kinds of calculate way that text put forward join will not affect the host and guest view quantity of the picture obviously, and can carry on distorting the fixed position examination availably, thus attaining the purpose of the examination and the marking picture contents reliability.The research of this paper is occupying a forward position in the relevant field. It has important theoretical value and application prospect. The provided methods experiment results in this paper have important reference value in further studying of digital watermarking in developing relevant computer software.