（毕业论文 字数：3247 页数：6）摘要：讨论两种算法，第一种是基本LSB（Least significant bit）——最低有效位算法。用8比特的二进制来表示灰度图像的每一个像素值，所有像素的最低位构成的位平面显现随机性，改变最低位不会对视觉效果产生明显影响。因此用水印信息直接代替数字图像的最低位。第二算法是基于小波变换数字图像水印盲算法。先将载体图像进行小波变换，为了保证水印图像的不可见性，选择将水印嵌入到高频分量。在嵌入水印图像时，本算法用到了扩频技术的思想，嵌入的并不是水印序列本身，而是根据密钥KEY生成的随机序列。通过计算相关度实现不使用原载体图像就能提取水印的盲算法。实现对两种算法优缺点和应用的场合的比较。而且通过仿真实验结果对比，讨论两种算法的对几种攻击的抵抗能力。

关键词：数字图像水印；LSB；小波变换；扩频技术

The Comparative Research of Robust Algorithm for Digital Watermarking
Abstract: Digital watermarking has been proposed as a solution to the problem of copyright protection of multimedia documents in networked environments. It makes possible to embed a watermarking (such as identification data, serials number, text or image etc) to multimedia documents allowing copyright protection, secret communication, document authentication and so on. This paper implement tow algorithm schemes. First is the LSB(Least significant bit). In this scheme we can replace the least digit of digital image with watermarked information. Second, a discrete wavelet transform(DWT) based digital image watermarking blind scheme has been realized applying the spread spectrum technology, which is not embedded watermarking sequence itself directly, but the random sequence according to a KEY. Through calculation of the correlation, the embedded watermarking was successfully extracted blindly without original vector images. The advantage, the disadvantage and the application occasion of these two schemes were compared. Last, the diversity of robustness against some styles of attack between them were presented by the means of the experiment result.
Key words: Digital Watermarking；LSB；Wavelet Ttransform；Spreadspectrum Technology

目录

1 前言
2 LSB水印算法与基于小波变换的扩频水印算法
3 实验结果分析
4 总结

1 前言
随着通信、计算机和网络技术的飞速发展，数字图像的高速传输、处理和存储已成为现实，但是由于网上的数字图像很容易被截获、复制及篡改，严重侵犯了单位或个人的知识产权。为解决这一问题，近几年国际上提出了一种全新的信息安全技术，即数字水印技术，并广泛应用于图像、视频和音频等数字媒体。由于它在版权保护、真伪鉴别、秘密通信和隐含标注等领域有着广泛的应用前景，因此它将成为一个非常重要的研究领域[1][2]。