【作者】 邓铭辉；

【导师】 郝燕玲；

【作者基本信息】 哈尔滨工程大学 ， 导航、制导与控制， 2005， 博士

【摘要】 近年来,多媒体存储与传输技术的不断进步,尤其是Internet技术的盛行,带动了数字媒体应用的迅猛发展,各种形式的多媒体作品包括图像、视频、音频等得以网络的途径向外发布,这些技术给人们带来了极大的方便,但随之而来的副作用也十分明显,例如任何人都可以通过网络轻而易举地得到他人的原始作品,尤其是数字化的图像、音乐、电影等,甚至有些人不经作者的同意而对原作品任意加以复制、修改,严重地侵害了作者的著作权,因此如何在网络中实施有效的版权保护和解决信息安全的问题,也就成为了一个迫在眉睫的研究课题。 在这种情况下,一种专门解决互联网上多媒体信息安全的技术——数字水印技术诞生了,它将水印嵌入到数字化媒体中,然后通过对它的检测(提取)来对图像的使用情况进行跟踪,从而实现隐藏传输、存储、版权保护等功能。目前数字水印已经成为多媒体版权认证和完整性保护的有效手段。 本文以静止数字图像作为研究对象,根据图像处理理论和水印技术的自身特性出发,深入分析几何攻击对数字水印的鲁棒性影响以及对图像本身的影响,通过理论推导和实验证明寻找到适合于抗几何攻击的图像水印理论与技术,分别利用3D小波变换理论,时频分析理论,DCT变换理论,单向Hash函数加密和Haar正交函数系理论对数字图像水印的抗几何攻击的鲁棒性进行了系统的研究,提出了一些新的理论思想和技术方案,从理论和实践上部分解决了数字水印所面临的几何攻击所导致的鲁棒性差和可检测性差问题,实现了抗几何攻击的鲁棒数字水印技术,主要研究内容如下: 1.对图像任意裁剪、旋转和缩放参数的估计算法的研究 针对几何变换(裁剪、旋转和缩放)对数据同步性的破坏提出几何参数估计算法,进行几何变换图像和原图像的配准,实现水印的可靠检测。利用边缘图像傅立叶变换的旋转不变性和差分相关技术准确估计裁剪图像的倾斜角度,通过二维相关函数计算相对位移,求得裁剪图像在原图像中的位置,从而将裁剪图像与原图像的配准。采用空域差分相关技术准确估计缩放图像的参数,实现与原图像的配准。 2.应用DCT变换和单向Hash函数加密理论的鲁棒水印技术研究 根据离散余弦变换理论和基本单向Hash函数加密提出了一种抗几何攻击的鲁棒数字水印技术,利用单向Hash函数来决定数字水印的嵌入位置与嵌入强度,使水印的嵌入位是伪随机序列,对于未被授权的使用者,很难检更多还原

【Abstract】 Recently, the development of multimedia storage and transmission technology, especially the popularization of the Internet technology 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, musics 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 informations hiding, storing, copyright safeguarding by tracking the use of the image by detecting the watermarks. At present, watermark technology becomes a kind of effective means to multimedia copyright authentication and its integrity safeguarding.This paper takes still images as example, analusizes the inflences of geometric attacks on the robustness of digital watermark and the image itself, and finds the image watermark theory and technologies being fit for resisting the geometric attacks via theory research and experimentation testifying. It makes use of 3D wavelet transformation theory, time and frequency analysis theory, DCT transformation theory, unilateralism Hash functions encrption and Haar orthogonal function systems to make the systematic and important investigation on the robustness of digital image resisting to the geometric attacks, raises some new theory thoughts and technology projects, partly resolve the problems of mistakes on the robustness and examination of watremarks because of the geometric attacks on the digital image and implement the robust watermark technology resist geometric attacks.1. Research on estimating algorithm of image random parameters of shearing, ratation and zoomingTo the damage of geometric transformation (shearing, ratation and zooming)on the data synchronization, the geometric parameter estimating algrithm is introduced in this paper to make geometric transformation image to match the original image and implement the credible examination of watermark. Tis algrithm makes use of the ratation invariability of Fourier transformation on the edge image and difference correlation technology to exactly compute slope angle and computes 2D correlation functions to calculate comparative displacement, to gain the position of the shearing image in the original image, and to make the shaering match the orignal image. This paper adopts the space difference correlation technology to exactly estimate the parameters of the zooming image and to match orignal image. This algrithm is practical.2. The research of robust watermark technology applying the DCT transformation and unilateralism Hash functions encrption theoryThis paper introduces a kind of robust digital watermark technology resisting geometric attacks on the base of the DCT transfonnation and unilateralism Hash functions encrption theory, decides the embedding positions and embedding extent. The positions of watermark are false random sequences and for the unaccredited users it is very impossible to detect the presence of watermark. The original owner of watermark can assure the safety of the watermark resisting the attacker. This algrithm applies the 8 X 8 DCT transformation technique to embed watermark into the middle frequence parts and shows excellent robustness and imperceptility. This algrithm applies the EIGFamal watermark encrption scheme and this algrithm is very safe.3. The research of robust digital watermarking algrithm against geometric attacks based on Haar orthogonal function systemThe deep research in the bridge function theory leads to that the real generalized bridge function system includes real multi-value Haar function system. The real multi-value Haar function system is a kind of self-contained generalized orthogonal function system. This paper introduces the robust digital watermarking algrithm against geometric attacks based on Haar orthogonal function system. The proposed algrithm makes the Haar orthogonal transform on the image and the significant middle frequently coefficients in the transformation matrix are picked up, on the base of characteristics of the image visual system and the Haar orthogonal transform. The watermark is adoptively weighed to the middle frequently matrix with zero watermark technique. This algrithm shows excellent qualities of resisting attacks and implement favorable robustness andvalidity.4. The research of robust digital image watermark algrithm on the base of 3D wavelet transformationThis paper introduces a kind of 3D wavelet transformation digital watermark algrithm on the base of the disperse wavelet transform and there-dimensional wavelet transformation on the video sequences. This algrithm splits the original image to a sense of image videos and the watermark is adaptively weighed to the different positions of the middle frequency region in the two-dimensional wavelet transformation of image videos and makes use of haracteristics of the image theory and human visual system. The algrithm shows excellent advantage against shearing attack and can clearly detect the watermark when a majority of the image is sheared. Abundant experiments prove the feasibility of this technology and this algrithm is a new ideology and solving project without fail.5. Applying the time-frequency analysis theory, research of robust image watermark technology based on the two-dimensional Radon-Wigner transformationA robust image watermarking algrithm resisting geometric distortions in two-dimensional space time-frequency distributions domain is proposed. This watermarking is davactericed by a linear frequency change and the two-dimensional Radon-Wigner transformation is used to detect the watermark. The two-dimensional chirp signals are used as watermarks and this type of signals is resistant to all stationary filtering methods and exhibits geometrical symmetry. In the two-dimensional Radon-Wigner transformation domain, the chirp signals used as watermarks change only its position in space time-frequency distribution, after applying linear geometrical attack, such as scale rotation and cropping. The watermark thus generated is invisible and is robust to geometrical attacks. Compared with other watermarking algorithms, this algorithm is more robust, especially against geometric distortion, while having excellent frequency properties. The proposed algorithm is a kind of novel technology that has a happy future.更多还原