基于小波变换数字图像水印盲算法

电子通信论文编号:TX037        论文字数:18735,页数:40

目录
摘要   ii
ABSTRACT   iii
第一章  绪论   1
1.1  本课题研究的背景及意义   1
1.2  数字图像水印的发展历程及其现状   2
1.2.1数字图像水印的研究历史   2
1.2.2国内外现状   3
1.3  论文的组织   4
第二章  数字图像水印技术研究   5
2.1  数字图像水印技术及其通用模型   5
2.2  数字图像水印的基本类型   7
2.3  数字图像水印的基本特征   7
2.4  数字图像水印的应用   9
2.5  数字图像水印的性能分析   9
第三章  小波域算法研究   11
3.1  小波的定义   11
3.1.1小波函数   11
3.1.2连续小波变换   11
3.2  离散小波变换   12
3.2.1离散小波函数   12
3.2.2离散小波变换   13
3.2.3多分辨分析   13
3.2.4二维离散小波变换快速算法   14
3.2.5离散图像的二维正交小波分析   15
3.3  小波在数字图像水印中的应用   16
第四章  基于小波变换的扩频数字图像水印盲算法   19
4.1  图像的小波分析   19
4.2  扩频技术的基本原理   19
4.3  水印的嵌入算法  21
4.4  水印的检测算法  23
4.5  实验结果及分析   24
第五章  总结与展望   28
5.1  工作总  28
5.2  工作展望  28
参考文献   29
致谢  30
附录   31

摘要
随着计算机和网络技术的飞速发展，数字图像、音频和视频产品愈来愈需要一种有效的版权保护方法，另外通信系统在网络环境下的信息安全问题也日益显露出来。数字图像水印技术为上述问题提供了一个有效的解决方案。所谓水印技术就是将数字、序列号、文字、图像标志等版权信息嵌入到多媒体数据中，以起到版权保护、秘密通信、数据文件的真伪鉴别和产品标志等作用。
本文提出了一种基于小波变换数字图像水印盲算法。该算法主要思想是，先将载体图像进行小波变换；考虑到高频分量只和图像的细节纹理有关，低频部分包含图像大部分能量，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CH、CV。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。在提取水印时，通过计算相关度，从而实现了不使用原载体图像就能提取水印的盲算法。
在成功实现了水印的嵌入和提取后，进行压缩、剪裁、加噪，旋转等攻击，并通过计算提取水印与原水印的相关度来分析算法的效率。实验结果表明：该算法使水印对如下攻击：压缩、剪裁，加噪，有良好的鲁棒性。

关键词： 数字图像水印，小波变换，扩频技术

ABSTRACT
The advent of the Internet and the wide availability of computers, scanners and printers make digital data acquisition, exchange and transmission a simple task. However, making digital data accessible to others through networks also creates opportunities for malicious parties to make salable copies of copyrighted content without permission of the content owner. 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 watermark (such as identification data, serials number, text or image etc) to multimedia documents allowing copyright protection, secret communication, document authentication and so on.
In this paper, a wavelet transform based digital image watermarking blind scheme has been proposed. A wavelet transform to vector images first. Taking into account that only high-frequency components the details of the image texture and low-frequency section contains images most energy, to choice of high-frequency components CH, CV for embedding watermark, in order to guarantee the watermark image is visible. Apply the spread spectrum technology to complete this scheme. It is not embedded watermark sequence itself, but the random sequence according to a KEY. Through calculation of the correlation, it is successful to extract the watermark algorithm blind when there are not original vector images.
After the successful implementation of the watermark embedding and extraction of the embedded watermark image, the following attack experiments have been done: compression, tailoring, increase noise, rotation, and calculated from the original watermark and the watermark relevance. The experimental results confirmed that this blind scheme is robust to a variety of attacks such as, the compression, the tailors, Gauss noise.

KEY WORDS:  digital watermarking, wavelet transform, spread spectrum technology