【作者】 许旻；

【导师】 孙涌；

【作者基本信息】 苏州大学 ， 计算机应用技术， 2008， 硕士

【摘要】 多媒体技术和网络技术近年来得到迅猛发展。随之而来的数字媒体的信息安全、知识产权保护和认证等问题也变得日益突出,这已成为数字世界中的一个非常紧迫的重要议题。数字水印技术是一种新兴的数字作品版权保护和防伪技术的重要手段,但是目前数字水印算法的抗攻击能力还不能完全达到应用的要求,如何提高水印算法的安全性成为目前需要解决的关键问题。本文系统分析了数字水印技术的原理、模型和分类,总结了其基本特征与典型算法,研究了衡量水印系统的技术指标和不同的水印攻击类型。以静止图像作为研究对象,结合了图像置乱、混沌等技术,提出了一种新的双重水印算法,该算法首先利用混沌和Arnold置乱技术对二值图像数字水印进行预处理,再将Arnold置乱后的鲁棒水印加载到原始彩色图像的绿色分量的离散余弦变换的中频系数中,然后将混沌置乱后的脆弱水印用LSB方法加载到之前含鲁棒水印的图像中,从而嵌入了双重水印;并能够根据原始图像提取出来水印。将双重水印算法应用到电子印章认证系统中,并进行了不可见性和相关性能的实验。实验结果表明,该算法能较好的提取出水印,鲁棒水印能有效抵抗JPEG压缩、剪切、加噪声、图像增强等攻击,具有良好的不可感知性和很强的鲁棒性,脆弱水印能反映出图像是否被篡改,具有很好的脆弱性。算法实现了电子印章的版权保护和数据完整性保护,方法简单可行,因此具有良好的实用价值。本文采用面向对象的分析与设计思想,根据提出的算法设计和开发了基于双重水印的电子印章原型系统,实现了对电子印章的水印的嵌入和提取。该系统与Windows操作系统紧密结合,操作简单快捷。更多还原

【Abstract】 Nowadays the multimedia technology and the Internet are developing rapidly. Digital watermarking technology is one of the newest methods of digital production copyright protection and antigorgery techniques, but the ability of the digital watermark arithmetic is not enough suitable for resisting many attacks. How to improve the security of the watermark arithmetic is becoming the key problem to be solved.In this thesis, the fundamental concept, general model, classification and characteristic of the digital watermarking are summarized. In addition, classic algrithms, the method to evaluate a watermarking system and watermarking attacks are analyzed together.Taking still images as example, a novel watermark algorithm for images based on double digital watermarking was proposed. The original binary watermark was firstly pre-pressed by Arnold scrambling and chaos encryption means. The Arnold scrambled watermark embedded into DCT mid-band frequency coefficient of original color image’s green components, and the watermark by chaos encryption embedded into by LSB method, so that the double watermark embedded into the original image. And the watermark can also be detected with the original image from watermarked image when needed.The watermark algorithm metioned above will application in an electronic seal system. In order to test the imperceptibility, robustness and brittleness of the algorithm, a lot of experiments are done. The experiment results demonstrate that the algorithm is imperceptible, very robust to attacks such as JPEG compression, cropping, additive noise and enhancement, and frangible to the tampered image. The algorithm achieves the protection of the electronic seal’s property authentication and data integrality. Because of the simpleness and convenience, they may be expected to have a better application prospect.Using the method of object oriented analysis and designing, this paper designs an electronic seal system based on the double digital watermarking. This system solves the problem of electronic seal system embed and recover. This system is tight coupling to the windows operating system, is easy to be used.更多还原