图像隐藏技术

摘要目前，信息隐藏技术作为新型的信息安全技术受到了越来越多人的关注。由于人的视觉敏感程度比较弱，所以图像文件是理想的信息隐藏载体。图像信息隐藏技术主要分为空间域方法和频率变换域方法。本文分别从空间域和变换域两方向研究不同算法，并加以实现。本论文首先介绍了图像信息隐藏技术中用到的一些基本概念和基本模型；接着介绍了空间域LSB、LHA和变换域DCT、DWT算法；然后对不同算法的性能进行了分析与讨论；最后，在MatlabR2009a软件下实现了相应的算法。实现结果表明，基于空间域方法具有较大的信息隐藏量和不可见性，但鲁棒性较差；而基于变换域方法具有较强的不可见性和鲁棒性，但信息隐藏量相对较小。关键词：LSB；LHA；DCT；DWT；信息隐藏量；不可见性；鲁棒性ABSTRACTAtpresent,theinformationhidingasanewinformationsecuritytechnologyisattractingmoreandmorepeople'sattention.Asthehumanvisualsensitivityisrelativelyweak,sotheimagefileisanidealcarrierofinformationhiding.Imageinformationhidingtechniquesaredividedintospatialdomainmethodsandfrequencytransformdomainmethods.ThispaperresearchesspatialdomainandfrequencytransformdomainalgorithmsandrealizesandverifiesthealgorithmsusingMatlabR2009a.First,somebasicconceptsandthebasicmodelusedininformationhidingtechnologyareintroducedinthispaper.ThenspatialdomainalgorithmsLSB,LHAandtransformdomainalgorithmsDCT,DWTareintroduced.Theperformanceandeffectivenessofthesealgorithmswerealsodiscussedinthepaper.Finally,thealgorithmsarerealizedusingMatlabR2009a.Implementationresultsshowthatthespatialdomainmethodshavelargeinformationhidingcapacityandinvisibility,butlessrobustness.Thefrequencytransformdomainmethodshashighinvisibilityandrobustness,butlesscapacity.KeyWords:LSB;LHA;DCT;DWT;informationhidingcapacity;invisibility;robustness目录第一章绪论....................................................................................................................11.1引言...........................................................................................................................11.2信息隐藏技术的研究...............................................................................................21.3信息隐藏技术中的一些典型算法...........................................................................31.3.1空间域信息隐藏技术....................................................................................31.3.2变换域信息隐藏技术....................................................................................31.4本文主要研究的内容...............................................................................................4第二章图像信息隐藏技术概述...............................................................................52.1引言...........................................................................................................................52.2信息隐藏技术的基本模型及术语...........................................................................52.3信息隐藏技术的主要特性.......................................................................................62.4信息隐藏系统的分类...............................................................................................72.4.1无密钥信息隐藏系统....................................................................................72.4.2私钥信息隐藏系统........................................................................................72.4.3公钥信息隐藏系统........................................................................................82.5本章小结...................................................................................................................9第三章图像信息隐藏技术算法的研究与实现................................................103.1引言.........................................................................................................................103.2伪随机序列在信息隐藏技术中的使用.................................................................103.2.1伪随机序列概述..........................................................................................103.2.2伪随机序列与信息嵌入位的选择..............................................................113.2.3对称密钥系统..............................................................................................123.3基于空间域的信息隐藏算法.................................................................................143.3.1LSB算法.......................................................................................................143.3.2LHA算法......................................................................................................183.4基于变换域的信息隐藏算法.................................................................................213.4.1DCT算法......................................................................................................213.4.2DWT算法.....................................................................................................253.5图像信息隐藏系统特性的分析与评价.................................................................293.5.1信息隐藏量..................................................................................................293.5.2不可见性......................................................................................................303.5.4鲁棒性..........................................................................................................313.5.5噪声攻击下的鲁棒性分析..........................................................................323.5.6滤波处理下的鲁棒性分析..........................................................................343.5.7其它攻击下的鲁棒性分析..........................................................................363.6本章小结........