基于人类视觉感知的下采样转码视频水印*

提出了一种抵抗下采样转码攻击的压缩域视频水印算法,算法对下采样频域空间的对应中低频系数进行分析来确定服从正态分布的水印序列的嵌入位置,根据Watson视觉感知模型的计算来控制嵌入水印时系数的修改幅度,从而满足图像感知失真限制要求。实验结果表明,该水印算法对一般的噪声攻击和转码过程中最普遍的下采样处理具有较好的鲁棒性,水印的提取采取相关检测原理,不需要原始视频信息。     

Chaotic model based semi fragile watermarking using integer transforms for digital fundus image authentication

This paper proposes a new reversible, imperceptible, semi fragile watermarking scheme for the authentication of digital fundus images that satisfies eight mandatory requirements. They are reversible, tamper detection, localization of modification, imperceptibility, capacity, complete blind detection, semi fragility and security. The proposed scheme generates the watermark dynamically using chaotic system and it is embedded using integer transform in reversible way. It precisely locates the tampering areas in the images and detects the watermark in complete blind approach without using the knowledge of both original image and watermark. It is found subjectively that 30,000 bits is the best size of the watermark for the proposed scheme to ensure the security and it is achieved for the PSNR value of around 60 dB at an average by retaining good level of imperceptibility. The proposed scheme is sensitive to the jittering, geometrical and filtering attacks and it modifies around 40 % of bits in the watermark for jittering and geometrical attacks, around 45 % of the bits in the watermark for filtering attacks to authenticate the images.     

Watermarking Relational Databases Using Optimization-Based Techniques

Proving ownership rights on outsourced relational databases is a crucial issue in today's internet-based application environments and in many content distribution applications. In this paper, we present a mechanism for proof of ownership based on the secure embedding of a robust imperceptible watermark in relational data. We formulate the watermarking of relational databases as a constrained optimization problem and discuss efficient techniques to solve the optimization problem and to handle the constraints. Our watermarking technique is resilient to watermark synchronization errors because it uses a partitioning approach that does not require marker tuples. Our approach overcomes a major weakness in previously proposed watermarking techniques. Watermark decoding is based on a threshold-based technique characterized by an optimal threshold that minimizes the probability of decoding errors. We implemented a proof of concept implementation of our watermarking technique and showed by experimental results that our technique is resilient to tuple deletion, alteration, and insertion attacks.     

Digital watermarking of text, image, and video documents

The ease of reproduction, distribution, and manipulation of digital documents creates problems for authorized parties that wish to prevent illegal use of such documents. To this end, digital watermarking has been proposed as a last line of defense. A digital watermark is an imperceptible, robust, secure message embedded directly into a document. The watermark is imperceptible both perceptually and statistically. Robustness means that the watermark cannot be removed or modified unless the document is altered to the point of no value. The watermark is secure if unauthorized parties cannot erase or modify it. Current watermarking schemes may be viewed as spread-spectrum communications systems, which transmit a message redundantly using a low-amplitude, pseudo-noise carrier signal. An example highlights the basic mechanisms and properties of spread spectrum and their relation to watermarking. Finally, specific issues in watermarking of text, images, and video are discussed, along with watermarking examples.     

一种自适应数字水印嵌入方法

As an effective method of ownership assertion for digital media,digital watermarking has been targeted especially in recent years.In this paper,an adaptive digital watermarking embedding approach is presented.By applying fuzzy c-means clustering algorithm based on human visual system,the clustering result may carry out the adaptive selection of the strength value of watermark.Compared with other means,the embedded watermark is more imperceptible and robust.In the same time,there is more anti-attack ability for embedded watermark in frequency domain than that in spatial domain.In the end,we also present results to show that our approach is applicable in practice.     

基于PE文件资源结构的水印算法

根据PE文件资源节结构和资源信息查找特点,提出了一种新的保护软件版权的水印算法.新算法引入了水印认证中心,利用大数分解难题生成具有法律效力的水印信息,用水印控制软件资源节结构图中节点的存放顺序,将水印信息隐藏于重排的资源结构图中.水印提取完全实现了盲检测.经分析,该算法能有效抵抗多种常见的攻击,具有较强的不可感知性和鲁棒性.     

基于局部极值点的音频盲水印算法

该文提出了一种新的音频水印算法。它充分利用了离散小波变换的多分辨率特性,在小波变换的细节部分搜索局部极值点,通过修改局部极值及其相邻点的幅度值,实现水印信息的嵌入。水印检测不需要参考原始音频。实验结果证明了该算法的鲁棒性和不可感知性。     

基于小波系数块能量分析的自适应数字水印算法

为增强水印的鲁棒性,提出一种基于小波变换的改进数字水印算法。该算法将宿主三级小波变换后的第三级细节子图分别分割成互不重叠的系数块,进而对各块能量进行统计分析以确定更适于水印嵌入的块,最后结合人类视觉系统的掩蔽特性,在所选块的最大系数上实现水印的自适应嵌入。理论分析与仿真结果表明应用本算法实现的水印具有更好的鲁棒性和不可见性。     

一种基于扩频的Contourlet域盲水印算法

提出一种基于量化的Contourlet水印算法。该算法首先对原始水印信息进行置乱,采用伪随机序列周期延扩的方法,生成扩频水印。然后对载体图像进行Contourlet变换,最后使用量化的方法,将产生的扩频水印嵌入到选定的Contourlet域系数中。实验结果表明,该算法具有很好的透明性,对一般的信号处理,例如,JPEG压缩、模糊和锐化等具有较好的鲁棒性。     

Robust and blind watermarking scheme for three dimensional anaglyph images

In this paper, a robust and blind watermarking scheme for three dimensional (3-D) anaglyph images is proposed. Since the computational cost of Red–Green–Blue (RGB) processing is quite high, we have used 3-D Discrete Wavelet Transform (3-D DWT) to decompose the image and process it directly. The watermark to be embedded is computed from the image and also the process involves watermark strength factor which scales the quality of the watermark. Jacket matrix is used due to its simplicity in the watermark embedding and extraction processes. Experimental results show that the proposed scheme is highly imperceptible and robust against various image processing and signal processing attacks. Comparisons with the state-of-the-art demonstrate the effectiveness of our scheme.     

基于DCT变换及SVD处理的音频数字水印算法

提出了一种基于离散余弦变换及奇异值分解的音频水印算法。首先对二值水印图像进行奇异值分解求出奇异值,然后对所得奇异值进行基于音频信号变换域性质的调制,并对音频信号进行离散余弦变换并计算水印嵌入点,最后将经过调制的水印信号嵌入。仿真试验证明这种自适应音频数字水印算法具有稳健性和不可觉察性。     

一种心理声学模型的自同步音频水印方案

提出了一种鲁棒的数字音频水印方案,该方案主要特点：（1）应用双重置乱机制,保证水印的安全性;（2）利用心理声学模型算法,确定水印嵌入强度;（3）应用同步机制,实现水印的自同步检测;（4）在离散小波变换（DWT）域嵌入水印,提高水印的抗攻击能力;（5）利用高效的嵌入算法,提高水印的检测效率。仿真实验表明,该方案不但具有良好的不可感知性,还对诸如重采样、重量化、叠加噪声、低通滤波、MP3压缩等攻击具有较好的鲁棒性。     

一种改进的K均值数字图像水印算法

提出了一种将K均值聚类方法应用到频域的图像水印算法。算法采用彩色图像作为原始图像,首先提取出原始图像的RGB分量,然后对不同的分量进行分块DCT变换,提取其中的DC分量,根据DC分量的大小进行聚类分析,得到其中数值较大的点用来嵌入水印信息,水印在嵌入之前进行置乱,以增强其安全性。仿真实验表明,水印是不可察觉的,并能有效地抵抗一些图像处理攻击,尤其对JPEG压缩具有良好的鲁棒性。     

一种适于多媒体流的鲁棒性水印方案

提出一种适用于多媒体流的鲁棒性水印算法,该方案将二值图像分段后经扩频调制作为水印信息分别嵌入视频帧的DCT域和音频的DCT域.实验结果表明:算法中嵌入的水印具有良好的不可觉察性,算法复杂度低,并且能够抵抗帧删除,帧插入和帧替换等攻击.对于针对音频信号的攻击,也具有良好的鲁棒性.此外,可以参照另一信号的相应信息,恢复被破坏的水印.     

基于遗传算法的图像数字水印

为了提高图像数字水印算法的实用性、顽健性及不可感知性,提出了一种改进的应用遗传算法的水印嵌入和提取方法。通过在DCT变换域中修改AC系数嵌入水印,可以提高嵌入速度,避免水印信息的损失;采用改进的遗传算法选择AC系数,同时优化嵌入水印后图像质量和顽健性这两个矛盾的因素。仿真结果表明,算法具有良好的抗攻击能力和不可感知性,节省约1/3的时间,提高了程序运行效率。     

Robust Motion Watermarking based on Multiresolution Analysis

Digital watermarking is one of commonly used solutions for copyright protection. A watermark should be imperceptible and robust to various attacks. In this paper, we address watermarking for motion data. Our watermarking scheme is based on two well-known ideas, so called multiresolution representation and spread spectrum. We embed a watermark into a motion signal by perturbing large detail coefficients of its multiresolution representation, and extract the watermark by analyzing perturbation of coefficients from a suspected signal. For more effective watermark extraction, we align suspected motion data to the original using dynamic time warping. Our scheme has merits of spread spectrum such as the resilience to common signal processing as well as the robustness to time warping.     

基于频率掩蔽效应的自适应音频数字水印技术

文章提出了一种基于频率掩蔽效应的自适应音频数字水印算法。嵌入的水印为视觉可辨的二值图像,水印能根据音频信号的频域掩蔽阈值进行自适应调整,水印的提取采用假设检验的方法。实验结果表明所嵌入的水印是不可感知的,该算法对大多数音频信号处理具有很强的鲁棒性,如重采样、MP3压缩和随机裁剪等操作。     

Chaotic based secure watermarking approach for medical images

In this paper, a chaotic based secure medical image watermarking approach is proposed. The method is using non sub-sampled contourlet transform (NSCT), redundant discrete wavelet transform (RDWT) and singular value decomposition (SVD) to provide significant improvement in imperceptibility and robustness. Further, security of the approach is ensured by applying 2-D logistic map based chaotic encryption on watermarked medical image. In our approach, the cover image is initially divided into sub-images and NSCT is applied on the sub-image having maximum entropy. Subsequently, RDWT is applied to NSCT image and the singular vector of the RDWT coefficient is calculated. Similar procedure is followed for both watermark images. The singular value of both watermarks is embedded into the singular matrix of the cover. Experimental evaluation shows when the approach is subjected to attacks, using combination of NSCT, RDWT, SVD and chaotic encryption it makes the approach robust, imperceptible, secure and suitable for medical applications.

     

小波分块的鲁棒性数字水印算法

利用小波分块思想,结合Arnold变换算法,提出了一种基于小波分块的水印算法,并且利用人类视觉系统的掩蔽特性,使水印的不可感知性和鲁棒性得到很好的统一。实验结果表明,该算法在对图像进行噪声、中值滤波、剪切等攻击有较强的鲁棒性。     

基于模数运算的DWT域数字音频水印

提出了一种基于DWT变换域的数字音频水印算法，对小波变换系数采取模2取余方法作为数字水印嵌入策略。通过仿真实验结果表明主要具有以下几个方面的特点：(1)水印隐蔽效果好，凭借人的感觉系统无法分辨出与原始音频的差别；(2)可以有效地抵抗噪声、低通滤波、有损压缩的处理；(3)在检测水印要受到密钥的限制，不知道口令的人是无法正确恢复出水印图像的。另外本算法在检测水印时不需要原始的音频信号。