基于视觉特性和小波分解的数字水印隐藏方法

本文提出了一种隐藏数字水印的新方法,该方法所隐藏的不是传统的序列码或比特流,而是将水印作为一幅二值图像来处理;并结合人眼视觉模型（ＨＶＳ）和图像的ＤＷＴ多尺度分解来隐藏水印。实验表明这种新方法在降低原始图像变换后视觉失真和提取的被隐藏水印图像失真两方面都达到较好的效果,鲁棒性也较好,这是一种很有发展前景的数字水印隐藏新方法。     

基于混合变换域的数字水印算法

提出了一种基于二维离散小波变换(DWT)和离散余弦变换(DCT)的混合变换域数字水印算法。通过小波变换得到载体图像的高频和低频系数,将低频系数作为一个子图像;再将二值水印图像置乱并编码,在子图像的离散余弦变换得到的系数中嵌入水印。该方法在水印检测和提取过程中都不需要原始图像。实验表明该方法水印隐藏性好,鲁棒性较好,抵抗放缩和局部攻击有很好的表现。     

一种基于二维DCT变换的图像信息隐藏方法

提出了一种基于二维DCT变换的图像信息隐藏方法,经过二维DCT变换后的图像能量集中在低频部分,考虑到人眼的视觉特性,图像的高频部分可视为视觉冗余部分,可以把有用信息隐藏在变换载体图像的高频部分,即以牺牲图像高频信息来达到信息隐藏的效果,通过MATLAB实现这一思想,对隐藏后的图像质量做了特征分析,并对下一步实验做出了设想.     

基于Logistic映射和Arnold置乱的数字水印算法

提出了一种基于Logistic映射和Arnold变换的DCT域数字水印算法。利用Arnold变换将原始水印图像进行置乱,然后对图像进行分块DCT变换,结合Logistic映射控制水印信息的嵌入位置,把置乱后的水印图像嵌入到图像的DCT域中频系数中,进行分块DCT反变换得到水印图像。利用图像DCT系数的关系,实现了水印的盲检测。实验结果表明该算法不仅具有较好的隐蔽性,同时对常见的水印攻击具有较好的鲁棒性。     

基于DCT域的AVS视频盲水印算法

结合人眼的视觉特性,提出了一种基于DCT域的AVS视频编解码标准的视频盲水印算法.算法首先对水印图像进行增强的Arnold变换,得到置乱的二值水印图像;然后根据嵌入公式替换嵌入点的系数,将水印信息自适应嵌入到Ⅰ帧的DCT系数中.提取水印时不需要原始视频,可实现盲水印.实验结果表明,该算法对高斯、帧剪切、盐噪声等攻击,具有较好的稳健性和不可见性.     

基于DCT的大容量二值水印嵌入新算法

传统的基于DCT变换的二值水印嵌入算法通常是在分块系数矩阵中选择一对中频系数实现1bit水印信息的嵌入,水印嵌入容量有限,为提高载体图像的安全性,提出了一种新的基于DCT的大容量二值水印嵌入算法.本算法首先对二值水印图像进行Arnold置乱加密处理,其次对所选取的载体图像进行分块DCT变换,然后选择4个中频系数进行排序,充分利用两两之间的3个差值关系实现水印的嵌入.若待嵌入水印位为0,通过改变系数值使得差值大于或等于阈值A,若待嵌入水印位为1,通过改变系数值使得差值等于阈值B,最终使得每块选择4个系数值实现了3bit二值水印信息的嵌入,水印嵌入容量大大优于传统方法.仿真实验表明,本算法实现了大容量水印的嵌入与提取且抵抗图像裁剪、图像加噪、JPEG压缩等攻击效果较好.     

基于人类视觉的混沌阵列在图像上的水印算法

本文提出了一种新的使用混沌阵列,基于HVS视觉掩盖自适应的公开图像水印算法,利用四阶累积量定义了视觉掩盖中的噪声敏感度.该方法将混沌阵列作为水印嵌入到图像子块的DCT次低频系数中去,然后根据噪声敏感度进行视觉掩盖.实验结果表明,在噪声敏感度的作用下,视觉掩盖实现了自适应地调整水印嵌入强度;在无原始数据的情况下,通过使用密钥能够清晰地检测出水印的存在;在常见的信号失真和几何失真下(有损压缩,剪切等),水印具有很好的稳健性.     

MPEG-4自适应视频水印算法

为了更好地保证水印的鲁棒性和不可感知性,结合MPEG-4视频压缩原理以及人类视觉模型系统,提出一种自适应的视频水印算法。根据I帧图像离散余弦变换（DCT）后的直流系数（DC）以及中低频系数个数,设计自适应因子,对不同的图像块采用不同的嵌入强度,将水印嵌入到DCT变换后的低频系数中。实验证明,该算法能够很好地与人类视觉系统相适应,并对常见的攻击有很强的鲁棒性。     

基于HVS感知模型与数据压缩的可逆图像水印算法

提出了一种基于人类视觉系统(HVS)感知模型和数据压缩技术可逆图像水印算法.算法首先将原始图像进行分块,每块进行DCT变换,利用JND模型对变换域系数进行处理,得到每个像素最大可提取的有效位并提取.将提取出的有效位串进行压缩,得到压缩位串,将水印信息与压缩位串连接在一起嵌入原始图像,同时记录边信息,包括每个像素点的最大可提取有效位数目以及嵌入位置,提取时可据此边信息完全恢复原始图像,并得到水印信息.容置的大小取决于所使用的压缩算法,使用游程编码进行压缩.同时,运用人类视觉系统的感知模型,保证了嵌入水印后的图像的视觉质量.     

一种基于HVS和DC分量的DCT域数字水印算法

为增强数字水印的透明性和鲁棒性,提出了一种基于人类视觉系统和直流分量的DCT变换域数字水印算法。算法依据原始图像的纹理掩蔽特性确定水印信息的嵌入位置,依据照度掩蔽特性确定水印信息的嵌入强度,将二值水印图像嵌入到原始图像在DCT域的直流分量中。在仿真实验中与同等条件下的中频嵌入做比较,实验结果表明,该算法提取的水印具有良好的透明性和鲁棒性。     

A visual model weighted cosine transform for hiding watermark in images

Watermarking is a technique for labeling digital pictures by hiding secret information into images. Watermark embedding is a method to discourage unauthorized copying and identify the owner or distributor of digital data. In this paper, a new method is proposed. The watermark is processed as a visually recognizable pattern-binary image, which includes more information than the traditional symbol or ID number and is "extracted" instead of only "detected" to characterize the owner. The watermark is hidden in the host image by selectively modifying the middle-frequency part of the host image in conjunction with the human visual system(HVS) and the image discrete cosine transform(DCT). The experimental results show that this method can survive image cropping and image compression, and get better results, this is also a prospective method.     

基于奇异值分解的近无损可逆数字水印方案

提出一种基于奇异值分解(SVD)和可逆信息隐藏的近无损鲁棒水印方法。首先将图像分块,然后进行SVD分解,并将水印嵌入到其进去奇异值的U分量中,最后将可恢复载体图像的信息经可逆信息隐藏方法嵌入到水印图像中,在提取水印和恢复载体图像过程中都不需要原载体图像。实验证明,该算法不仅能使原载体图像近无损恢复,而且能有效地抵抗JPEG压缩、噪声干扰、低通滤波,剪切和旋转等典型的攻击,具有较强的鲁棒性。     

Robust digital watermarking algorithm based on continuous hyperchaotic system and discrete wavelet transform

Many digital watermarking methods have been pro-posedin the last fewyears[1 ,3].It is a tradeoff problemsince whenthe robustness of a watermarkincreases ,theperceptual quality of the contents will be degraded.Hence,the main goal of i mproving a watermarki…     

一种基于脆弱水印技术的图像认证方法

基于计算全息图编码的水印技术是一种脆弱水印技术,由于其极容易被破坏的特性,非常适合用于图像内容的认证,在图像的认证鉴定的时候,通过比较提取的水印和初始水印的相关性鉴定图像内容的完整性,可以有效防止篡改和对修改图像的欺骗性应用。同时,图像的内容被篡改时,水印信息应该提供图像被伪造的证据。利用计算全息图作为水印,嵌入的水印可能被使用傅里叶变换恢复,进而,宿主图像也能被利用同样的全息模式进行篡改和嵌入水印,为了避免这种弊端,还需要引入加密方法。     

Enhancing image watermarking methods with/without reference images by optimization on second-order statistics

The watermarking method has emerged as an important tool for content tracing, authentication, and data hiding in multimedia applications. We propose a watermarking strategy in which the watermark of a host is selected from the robust features of the estimated forged images of the host. The forged images are obtained from Monte Carlo simulations of potential pirate attacks on the host image. The solution of applying an optimization technique to the second-order statistics of the features of the forged images gives two orthogonal spaces. One of them characterizes most of the variations in the modifications of the host. Our watermark is embedded in the other space that most potential pirate attacks do not touch. Thus, the embedded watermark is robust. Our watermarking method uses the same framework for watermark detection with a reference and blind detection. We demonstrate the performance of our method under various levels of attacks.     

Design and statistical analysis of a hash-aided image watermarking system

This paper develops a joint hashing/watermarking scheme in which a short hash of the host signal is available to a detector. Potential applications include content tracking on public networks and forensic identification. The host data into which the watermark is embedded are selected from a secret subset of the full-frame discrete cosine transform of an image, and the watermark is inserted through multiplicative embedding. The hash is a binary version of selected original image coefficients. We propose a maximum likelihood watermark detector based on a statistical image model. The availability of a hash as side information to the detector modifies the posterior distribution of the marked coefficients. We derive Chernoff bounds on the receiver operating characteristic performance of the detector. We show that host-signal interference can be rejected if the hash function is suitably designed. The relative difficulty of an eavesdropper's detection problem is also determined; the eavesdropper does not know the secret key used. Monte Carlo simulations are performed using photographic test images. Finally, various attacks on the watermarked image are introduced to study the robustness of the derived detectors. The joint hashing/watermarking scheme outperforms the traditional "hashless" watermarking technique.     

Hidden digital watermarks in images

An image authentication technique by embedding digital "watermarks" into images is proposed. Watermarking is a technique for labeling digital pictures by hiding secret information into the images. Sophisticated watermark embedding is a potential method to discourage unauthorized copying or attest the origin of the images. In our approach, we embed the watermarks with visually recognizable patterns into the images by selectively modifying the middle-frequency parts of the image. Several variations of the proposed method are addressed. The experimental results show that the proposed technique successfully survives image processing operations, image cropping, and the Joint Photographic Experts Group (JPEG) lossy compression.     

Secure reversible visible image watermarking with authentication

This paper proposes a secure reversible visible watermarking approach. The proposed pixel mapping function superposes a binary watermark image on a host image to create an intermediate visible watermarked image. Meanwhile, an almost inverse function generates the recovery data for restoring the original pixels. To prevent unauthorized users from approximating the original pixels in the watermarked region, this method adds an integer sequence in the intermediate watermarked image. The sequence is composed of integers generated by two random variables having normal distributions with zero means and distinct variances. The variances facilitate a trade-off between the watermark transparency and the noise generated by unauthorized users. The proposed method also uses Lagrange multipliers to find the optimized variances for the trade-off. Finally, this method uses reversible data embedding to embed the recovery data and hash value for reversibility and authentication, respectively. Experimental results show the watermark visibility for test images along with the watermark transparency for different variances. Using the optimized variances, the watermarked image is at the balance between the watermark transparency and the unauthorized-user-generating noise.     

A robust region-adaptive dual image watermarking technique

Despite the progress in digital image watermarking technology, the main objectives of the majority of research in this area remain to be the improvement in robustness to attack. In this paper, a novel watermarking technique is proposed using a region-adaptive approach to further improve upon criteria. Watermark data is embedded on different regions of the host image using a combination of Discrete Wavelet Transform and Singular Value Decomposition techniques. The technique is derived from an earlier hypothesis that the robustness of a watermarking process can be improved by using watermark data which frequency spectrum not dissimilar to that of the host data. To facilitate this, the technique utilises dual watermarking technologies and embed parts of the watermark images into selected regions in the host image. Our experiment shows our technique has improved the robustness of the watermark data to image processing attacks and geometric attacks, thus validating the earlier hypothesis.