Improved image tamper localisation using chaotic maps and self-recovery

In this paper an image tamper localisation scheme is proposed in which authentication bits of a 2 × 2 image block are generated using the chaotic maps. Further the scheme is improved by including a self-recovery method to recover the tampered regions. To improve the quality of the recovered image, two different sets of restoration bits of a block are generated and each one is embedded into randomly selected distinct blocks. The proposed tamper detection scheme performs better than some of the recent schemes proposed by the researchers. The experimental results demonstrate the accuracy and fragility of the tamper detection scheme, and the efficacy of the recovery method.     

彩色图像DWT变换下的块SVD零水印

为了提高水印技术的鲁棒性,提出了彩色图像离散小波变换(DWT)下的块奇异值分解(SVD)的零水印.首先对原始载体图像进行离散小波变换,然后选择低频子带进行分块,且对每一块进行奇异值分解,水印则由分解得到的最大前m个奇异值产生.实验结果表明,算法对各种攻击有较强的鲁棒性.     

基于DWT-DFT和SVD域的盲水印算法

提出了一种基于离散小波变换、离散傅里叶变换和奇异值分解相结合的盲水印算法。该算法对原始图像进行一级离散小波变换后选择低频子带图像作分块离散傅里叶变换,然后对分块离散傅里叶变换的幅度谱进行奇异值分解,选择最大奇异值并采用量化嵌入方法实现水印的嵌入和盲提取。为了提高算法对旋转攻击的鲁棒性,采用基于Radon变换的检测算法对待检测图像进行旋转校正。实验结果表明,该算法对一些常规攻击和几何攻击都具有较强的鲁棒性。     

基于脆弱水印的图像认证算法研究

很多基于分块的图像认证算法为了提高安全性,采用大分块或者分块相关技术,因而牺牲了定位精度.通过对各种攻击的分析,提出了一种基于脆弱水印的图像认证方案.使用SHA512算法和基于背包问题的单向函数来产生水印,使用滑动窗口技术和层次结构来嵌入水印,使强加密算法在小分块上得以应用.该方案不但能够抵抗矢量量化等目前已知的各种攻击,而且能够将篡改定位到2×2大小的像素块上.理论分析和实验数据表明,该方案在保证系统安全性的同时,有效地提高了篡改定位的精度.     

基于奇异值分解的Contourlet域图像水印算法

针对小波变换由于方向性缺乏而无法有效稀疏地表示图像本身几何结构的问题,结合Contourlet变换和奇异值分解的优点,提出了一种Contourlet变换域内基于奇异值分解的数字水印算法。宿主图像经过两层Contourlet分解后,生成一系列多尺度多方向的子带,选取第二层分解中能量最大的子带进行大小为4×4的互不重叠的分块,并进行奇异值分解,再将置乱后的原始二值水印信息嵌入到奇异值矩阵中。实验结果表明,该算法实现简单,透明性良好,对常规攻击和几何攻击具有较强的鲁棒性,且优于一般的小波域算法。     

A blind image copyright protection scheme for e-government

An efficient blind copyright protection for e-government document images is proposed through a combination of the discrete cosine transform (DCT) and the singular value decomposition (SVD) based on genetic algorithm (GA). This combination could lead the watermarked image to be resistant to various attacks as well as to improve its performance, security and robustness. DCT, in this case, is applied to the entire image and mapped by a zigzag manner to four areas from the lowest to the highest frequencies. SVD, meanwhile, is applied in each area and then the singular value of DCT-transformed host image, subsequently, is modified in each area with the quantizing value using GA to increase the visual quality and the robustness. The host image is not needed in the watermark extraction and it is more useful than non-blind one in real-world applications. Experiment results demonstrate that the proposed method outperforms other existing methods under several types of attacks.     

抗重压缩编码的3D-HEVC视频零水印算法

考虑到零水印算法的优越性以及目前针对3D高效视频编码标准的视频水印算法少的情况,提出了一种抗重压缩编码的视频零水印算法。首先,利用I帧的深度图及非I帧的运动矢量和编码单元划分情况对水印的构造位置进行选择。其次,通过全相位双正交变换及奇异值分解对16x16块进行处理,获取最大奇异值的最高有效位作为最终的特征信息。最后,得到的特征信息与图像水印进行异或生成零水印并进行零水印注册。实验结果表明,在不同量化参数的重压缩编码攻击、基于帧及重压缩编码混合攻击和信号处理及重压缩编码混合攻击下,本文算法具有良好的鲁棒性。      

一种新的自适应数字水印算法

为了提高数字水印抗击各种图像攻击的性能和保持图像的稳健性和不可见性,提出了一种基于离散小波变换(DWT),SVD(singular value decomposition)奇异值分解水印图像和原始载体图像的离散余弦变换(DCT)的自适应水印嵌入算法,主要是将水印图像的两次小波变换后的低频分量潜入到原始图像分块经过SVD分解的S分量矩阵中,同时根据图像的JPEG压缩比的不同计算各个图像块的水印调节因子。实验证明该算法在抗击JPEG压缩、中值滤波、加噪等均具有很好的鲁棒性,嵌入后的图像的PSNR达到38,具有良好的视觉掩蔽性     

Watermarking based image authentication and tamper detection algorithm using vector quantization approach

In the present work, a novel image watermarking algorithm using vector quantization (VQ) approach is presented for digital image authentication. Watermarks are embedded in two successive stages for image integrity verification and authentication. In the first stage, a key based approach is used to embed robust zero level watermark using properties of indices of vector quantized image. In the second stage, semifragile watermark is embedded by using modified index key based (MIKB) method. Random keys are used to improve the integrity and security of the designed system. Further, to classify an attack quantitatively as acceptable or as a malicious attack, pixel neighbourhood clustering approach is introduced. Proposed approach is evaluated on 250 standard test images using performance measures such as peak signal to noise ratio (PSNR) and normalized hamming similarity (NHS). The experimental results shows that propose approach achieve average false positive rate 0.00024 and the average false negative rate 0.0012. Further, the average PSNR and tamper detection/localization accuracy of watermarked image is 42 dB and 99.8% respectively; while tamper localization sensitivity is very high. The proposed model is found to be robust to common content preserving attacks while fragile to content altering attacks.     

Blob-Harris特征区域结合CT-SVD的鲁棒图像水印算法

为了提高水印图像对几何攻击的鲁棒性,提出了一种Blob-Harris特征区域结合轮廓波变换(Contourlet transform, CT)和奇异值分解(singular value decomposition, SVD)的鲁棒图像水印算法。首先在原始图像经过Contourlet变换后的低频分量中提取斑点(Blob)块区域并利用Harris角点检测进行特征点提取,然后根据各个特征点的特征尺度确定其特征区域,选择适中的互不重叠的特征区域,将其四周补零后进行归一化操作,最后将经过小波变换提取的低频水印图像进行奇异值分解,并重复嵌入到每一个归一化圆形特征区域的内接正四边形当中。仿真实验结果表明,本文算法除了对常规攻击有很好的抵抗力之外,对几何攻击也有相对较强的鲁棒性,特别是缩放、平移、剪切以及其组合攻击,NC值均达到0.94以上。      

A transcoding-resistant video watermarking algorithm based on corners and singular value decomposition

The singular value decomposition (SVD) mathematical technique provides an elegant method for extracting algebraic features form an image. When a small change is added to singular values, great variance of image doesn’t occur, and singular values in an image are less affected if general image processing is performed. Because singular value matrix of an image has good stability, the watermark can be embedded to this matrix without causing large variation in the stego-image. The reason of causing block effects and flicker in the traditional watermarked video using SVD is firstly analyzed in this paper. Based on the feature of SVD and that human eyes are not sensitive to the changes in corner area of each frame of video, we embed watermark into blocks with corner inside using quantization index modulation. We analyze the validity of the proposed algorithm about synchronizing error, block effects, and flicker. The experiment shows that the proposed approach has an excellent robustness against transcoding and some normal attacks, such as adding noise, re-encoding and so on without causing any block effects and flicker. The result also shows that the correct rate of extracting watermark can achieve 98 % per second.     

Block-based SVD image watermarking in spatial and transform domains

The idea of this paper is to implement an efficient block-by-block singular value (SV) decomposition digital image watermarking algorithm, which is implemented in both the spatial and transforms domains. The discrete wavelet transform (DWT), the discrete cosine transform and the discrete Fourier transform are exploited for this purpose. The original image or one of its transforms is segmented into non-overlapping blocks, and consequently the image to be inserted as a watermark is embedded in the SVs of these blocks. Embedding the watermark on a block-by-block manner ensures security and robustness to attacks such like Gaussian noise, cropping and compression. The proposed algorithm can also be used for colour image watermarking. A comparison study between the proposed block-based watermarking algorithm and the method of Liu is performed for watermarking in all domains. Simulation results ensure that the proposed algorithm is more effective than the traditional method of Liu, especially when the watermarking is performed in the DWT domain.     

Efficient video watermarking based on singular value decomposition in the discrete wavelet transform domain

This paper presents an efficient, robust, and imperceptible video watermarking technique based on singular value decomposition (SVD) performed in the Discrete Wavelet Transform (DWT) domain. In the proposed DWT-based SVD video watermarking method, the video frames are transformed with the DWT using two resolution levels. The high frequency band HH and the middle frequency bands LH and HL are SVD transformed and the watermark is hidden in them. The proposed DWT-based SVD video watermarking method is characterized by two improvements: (1) a cascade of two powerful mathematical transforms; the Discrete Wavelet Transform (DWT)-based SVD using additive method, and (2) an error correction code is applied and embeds the watermark with spatial and temporal redundancy. The aim of these improvements is to increase robustness against attacks based on video characteristics and the robustness against image processing attacks, realize high security level, protect the watermark against bit errors and obtain good perceptual quality. The proposed DWT-based SVD video watermarking method has been tested in the presence of video and image processing attacks and experimental results proved that the proposed DWT-based SVD video watermarking method survives attacks based on video characteristics and image processing techniques.     

一种面向多波段数字遥感影像的版权保护方案

针对数字遥感影像大尺度、多波段、高保真的特性,提出了一种新颖的版权保护方案.理论分析了第一奇异值向量方向的稳定性;通过比较某一参考向量分别与两个选定数据块的第一奇异值向量的夹角关系,建立单波段图像水印特征;然后为遥感影像的多波段特性提出了水印检测的快速策略与一般策略.实验表明该方案对波段攻击与灰度攻击、组合攻击等保持图像内容的操作具有较强的鲁棒性.     

基于DWT-SVD的大容量音频水印算法

在音频水印领域,嵌入大量水印而不影响宿主音 频的听觉质量,同时具有良好的鲁棒 性,仍然是一项具有挑战的工作。针对这一问题,本文提出了一种大容量,透明,鲁棒的音 频水印算法。首先对音频应用2级离散小波变换(DWT),并选取低频分量作奇异值分解(SV D),然后将水印嵌入在奇异值矩阵的非对角线元素中,可同时提高算法的透明性和嵌入容 量。另外,利用汉明码编码提升水印的鲁棒性和安全性。仿真实验结果表明,所提算法在平 均信噪比37.75 dB的情况下,可以达到5512 bps 的嵌入容量,对噪声添加、滤波、剪切、压缩等各种信号处理攻击具有良好的鲁棒性。     

Hierarchical watermarking for secure image authentication withlocalization

Several fragile watermarking schemes presented in the literature are either vulnerable to vector quantization (VQ) counterfeiting attacks or sacrifice localization accuracy to improve security. Using a hierarchical structure, we propose a method that thwarts the VQ attack while sustaining the superior localization properties of blockwise independent watermarking methods. In particular, we propose dividing the image into blocks in a multilevel hierarchy and calculating block signatures in this hierarchy. While signatures of small blocks on the lowest level of the hierarchy ensure superior accuracy of tamper localization, higher level block signatures provide increasing resistance to VQ attacks. At the top level, a signature calculated using the whole image completely thwarts the counterfeiting attack. Moreover, "sliding window" searches through the hierarchy enable the verification of untampered regions after an image has been cropped. We provide experimental results to demonstrate the effectiveness of our method.     

基于QR分解的强鲁棒性双彩色盲水印算法

提出了一种将彩色快速识别(QR)码作为水印嵌入彩色宿主图像的强鲁棒性盲水印算法。首先 对彩色宿主图像分通道进行离散小波 变换(DWT)和分块QR分解得到非重叠的酉矩阵,然后将QR码分通道置乱加密归一化后嵌入到 宿主图像对应通道 酉矩阵的系数差中。仿真实验结果表明,本算法在满足不可见性的同时具有较强的鲁棒性; 相比现有算法, 本算法不仅能够抵抗旋转和裁切攻击,在JPEG压缩和噪声滤波攻击方面的抵抗能力也有较 大提升;而且本算法属于盲水印技术,具有较大的实际应用价值。     

基于子块区域分割和自嵌入技术的全盲多功能图像水印算法

利用子块区域分割思想和自嵌入技术提出了一种只利用攻击图像就能进行版权鉴别和内容认证的全盲多功能图像水印算法。将原始图像分割成不重叠的子块,对每个子块进行离散余弦变换,将每个子块离散余弦变换矩阵分成为区域1和区域2两部分,然后对区域1进行奇异值分解,通过判断奇异值均值的最高位数字奇偶性产生特征水印,然后通过调整区域2的2个离散余弦变换交流系数大小自嵌入特征水印,最后对每个子块进行逆离散余弦变换得到含水印图像。算法通过结合将区域1产生的特征水印自嵌入区域2和在区域2盲提取认证水印实现全盲检测和多功能。实验结果表明,算法既能实现版权保护又能实现内容认证,而且还具有区分恶意篡改和无意篡改的能力。     

一种基于DWT_SVD的抗几何攻击彩色图像水印算法

针对传统离散小波变换(DWT)水印算法不能较好地抵抗几何攻击的缺点,提出了一种基于离散小波变换(DWT)和奇异值分解(SVD)相结合的彩色图像水印新算法。首先对原始彩色载体图像进行RGB三基色分解,然后进行离散小波变换,再选取四个子块的四分之一重构成新子块,并进行二次离散小波变换,最后对其低频部分进行奇异值分解嵌入水印信息,得到嵌入水印的彩色图像。实验结果表明,该算法能够较好地抵抗诸如高斯噪声、椒盐噪声、压缩等常规攻击,并对大角度旋转、任意角度旋转、剪切加旋转等几何攻击也表现出了较强的鲁棒性,其总体性能明显优于传统的DWT水印算法。     

基于混沌置乱的分块自嵌入水印算法

针对分块自嵌入水印算法的安全性和不能有效判断图像篡改块的问题,提出一种基于混沌置乱的分块自嵌入算法.该算法将由图像块生成的水印按空间位置生成二值水印图像,利用混沌序列对其置乱加密后嵌入到图像的最低位,认证时根据设定的阈值能有效定位图像内容被篡改的图像块.实验仿真和理论分析表明,该算法在保持原算法篡改恢复效果的基础上,无论是否有水印被改变,均能有效判断图像内容被篡改的图像块,且具有更高的安全性.