基于DCT的数字水印算法的研究

基于DCT的数字水印算法的研究Research of Digital Watermarking Algorithm Based on Discrete Cosine

Transform

摘要

近年来，由于网络的迅猛发展，越来越多的多媒体信息已经走向数字化。人们可以从网上更加方便的取得各类信息，可以更加方便的对别人的作品进行篡改，复制等，由此带来的版权维护问题也日益严重。版权维护也越来越受到人们的关注了，数字水印技术是解决这类问题最有效的手段，所以数字水印技术现在已然成为了研究的热点。

本文是对基于DCT域数字水印算法的研究，简要介绍数字水印的发展，基本原理等，在MATLAB环境中完成两种基于DCT域数字水印算法的设计。第一种是基于DCT图像全局变换的数字水印算法，而第二种则可以认为是第一种算法的改进，是基于DCT域分块水印算法。然后对于水印系统的鲁棒性，进行一些攻击测试，有盐噪声攻击、高斯噪声攻击、旋转攻击、剪切攻击、JPEG有损压缩攻击等，对比分析哪种算法更好。虽然说该课题只不过是对现有的数字水印技术进行了一个比较简单的研究，但是让我们充分认识到了数字水印技术对我们日常生活的重要性。

关键词：数字水印DCT 攻击测试

Abstract

In recent years,with the rapid development of the network,more and more multimedia information has been digitized.People can obtain various kinds of information from the Internet more convenient, the work of others will be altered and copied more convenient, copyright protection issues are also increasingly serious. People are more and more concerned about copyright protection, digital watermarking technology is the most effective means to solve these problems, so the digital watermarking technology has become a hot topic now.

This article is to study based on DCT-domain digital watermarking algorithm, introduced the development of digital watermarking and the basic principles etc,completed two design schemes based on DCT-domain digital watermarking algorithm in MATLAB environment. The first one is based on digital image watermarking algorithm global transformation of DCT, while the second one can be considered to improve the first algorithm, which is based on DCT-domain block watermarking algorithm. Then for the robustness of the watermarking system, we performed some attack test, salt noise attack, Gaussian noise attack and spin attack, cropping attack, JPEG compression attack, in order to prove which is better. Although the subject is a relatively simple research for the existing digital watermarking technique , but it let us aware of the importance of digital watermarking technology in our daily life.

Key words:Digital watermarking DCT Robustness Attack test

目录

摘要 ....................................................................................................................................... I Abstract ............................................................................................................................... I I 绪论 .. (1)

1 数字水印的介绍 (3)

1.1 数字水印定义及基本特点 (3)

1.1.1 定义 (3)

1.1.2 基本特点 (3)

1.2 数字水印基本原理 (3)

1.2.1 水印嵌入 (4)

1.2.2 水印提取 (4)

1.3 数字水印分类 (5)

1.4 数字水印的常见算法 (6)

1.4.1 空域算法 (6)

1.4.2 变换域算法 (6)

1.4.3 JPEG压缩域算法 (6)

1.4.4 NEC算法 (7)

1.4.5 生理模型算法 (7)

2 开发工具和环境 (8)

2.1 MATLAB简介 (8)

2.2 MATLAB语言特点 (8)

3 基于DCT域数字水印算法实现 ................................................... 错误!未定义书签。

3.1 离散余弦变换 (9)

3.2 基于DCT全局变换算法 (9)

3.2.1 水印的嵌入思路 (9)

3.2.2 水印的提取思路 (10)

3.2.3 仿真结果 (10)