Method for combating random geometric attack on image watermarking

A method for amending StirMark random geometric attacked watermarked images is introduced. The proposed scheme uses a reference image to identify the attacked pixels, then exchanges them for pixels from the original unwatermarked image. It is shown that the watermark can be successfully detected after the attacked image is corrected     

Secret and public key image watermarking schemes for imageauthentication and ownership verification

We describe a watermarking scheme for ownership verification and authentication. Depending on the desire of the user, the watermark can be either visible or invisible. The scheme can detect any modification made to the image and indicate the specific locations that have been modified. If the correct key is specified in the watermark extraction procedure, then an output image is returned showing a proper watermark, indicating the image is authentic and has not been changed since the insertion of the watermark. Any modification would be reflected in a corresponding error in the watermark. If the key is incorrect, or if the image was not watermarked, or if the watermarked image is cropped, the watermark extraction algorithm will return an image that resembles random noise. Since it requires a user key during both the insertion and the extraction procedures, it is not possible for an unauthorized user to insert a new watermark or alter the existing watermark so that the resulting image will pass the test. We present secret key and public key versions of the technique.     

基于线性预测的图像可擦除水印算法

通过研究自然图像的空间相关性和线性预测方法,提出一种在图像中嵌入可擦除水印的新方法。该方法在图像分块的基础上,利用邻近像素之间的相关性在每一图像块中嵌入1位水印,水印信号是用有意义的水印图像,嵌入位置由预测样本的平均值和密钥决定,具有非常好的安全性和易碎性,水印的提取和擦除不需要原始图像。实验表明,该方法嵌入的水印不可见性好,擦除水印的图像与原始图像完全一致,适合于图像的精确认证。     

基于格的灰度级水印技术

提出一个新的灰度级水印算法．首先，使用量化技术对灰度级水印进行预处理，实现灰度级水印的数据压缩；然后，对原始图像进行小波分解，在小波域中使用格矢量量化技术构造水印的嵌人和提取算法．提取水印不需要原图像．为增强水印的安全性，使用混沌序列作为密钥对水印序列进行调制．实验结果表明，与同类算法相比该算法在获得较好感知质量含水印图像的同时提高了水印的鲁棒性．     

基于视点间关系预测的立体图像可逆水印

针对特殊应用领域的立体图像安全性问题,提出 了基于视点间关系预测的立体图像可逆水印, 能够无损地恢复原始立体图像。根据左右视点匹配像素具有较强相关性的特征,能够较 准确地预测立 体图像的像素,并建立峰值点较高的预测误差直方图。通过直方图峰值点的平移,并采用多 层水印嵌入, 从而达到较高的水印容量。此外,根据水印嵌入代价率,为峰值寻找最优零点,从而减少了 非水印嵌入的 数据平移量,提高了含水印立体图像的质量。实验结果表明,相比现有预测算法,提出的基 于视点间的预 测算法更加精确;在相同水印容量的情况下,本文方法的图像质量高于现有扩展的立体图像 可逆水印方法,在较大水印容量时,峰值信噪比(PSNR)的提高尤其明显。     

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。     

基于图像内容的脊波变换域数字水印模型和算法研究

在研究人类视觉(HVS)特性的基础上提出了一种在脊波变换域基于图像内容的数字水印模型。在此模型中,嵌入数字水印的强度归结于数字图像脊波系数的视觉掩盖效应,文中建立了脊波变换域人眼临界可见误差模型。图像的水印检测被归结为Neymann-PeaLrson准则下的统计模型,该模型被用来估算水印检测的最优阈值。作为算例,将临界可见误差模型结合扩展谱技术,提出了一种新颖的图像自适应水印算法,并给出了相应的实验结果。实验表明算法性能大幅度提高。     

DCT域下采样视频水印技术

根据DCT域Watson模型提出了一种抵抗下采样攻击的不可感知水印模型.用DCT域准卷积下采样方法得到图像的下采样版本,利用亮度特征和图像感知失真限制自适应确定被嵌入水印序列的区域、长度和强度,以使上采样水印图像具有良好的视觉效果和鲁棒性.实验结果表明该算法对噪声干扰及视频下采样具有较好的鲁棒性,而且不使用原始图像,就可进行水印的相关检测.     

A buyer-seller watermarking protocol

Digital watermarks have previously been proposed for the purposes of copy protection and copy deterrence for multimedia content. In copy deterrence, a content owner (seller) inserts a unique watermark into a copy of the content before it is sold to a buyer. If the buyer sells unauthorized copies of the watermarked content, then these copies can be traced to the unlawful reseller (original buyer) using a watermark detection algorithm. One problem with such an approach is that the original buyer whose watermark has been found on unauthorized copies can claim that the unauthorized copy was created or caused (for example, by a security breach) by the original seller. In this paper, we propose an interactive buyer-seller protocol for invisible watermarking in which the seller does not get to know the exact watermarked copy that the buyer receives. Hence the seller cannot create copies of the original content containing the buyer's watermark. In cases where the seller finds an unauthorized copy, the seller can identify the buyer from a watermark in the unauthorized copy and furthermore the seller can prove this fact to a third party using a dispute resolution protocol. This prevents the buyer from claiming that an unauthorized copy may have originated from the seller.     

结合二次差值扩展与插值扩展的可逆图像水印算法

为了提高现有可逆图像水印算法的视觉质量和嵌入 率,提出了一种结合二次差值扩展 和插值扩展的可逆图像水印算法。首先去除原始图像中的0和255像素 点;然后对去除0和255 像素点后构成的新图像进行互不重叠块划分并对划分出的每个图像块进行插值扩展;接着将 前一半置乱后的水印信息利用一次差值扩展嵌入到经插值扩展生成的图像块中;最后利用二 次差值扩展将剩余的一半水印信息嵌入到之前生成的水印图像中,去除扩展的像素点和并上 之前已去除的0和255像素点,以此生成最终的水印图像。实验结果表 明该算法不仅嵌入率高 ,而且有较高的视觉质量(平均PSNR值高达77.91 dB),能实现原始图像的完全恢复。和 其它基于差值扩展的可逆图像水印算法相比具有一定的优势,无需考虑嵌入区域的平滑度。     

Robust and reversible image watermarking in homomorphic encrypted domain

This paper proposes a robust and reversible watermarking scheme for the encrypted image by using Paillier cryptosystem. In the proposed method, the original image is divided into a number of non-overlapping blocks sized by 8 × 8 and Paillier cryptosystem is applied to encrypt the pixels in each block. Firstly, a data hider can calculate the statistical values of encrypted blocks by employing modular multiplicative inverse (MMI) method and looking for a mapping table. Then a watermark sequence can be embedded into the encrypted image by shifting the histogram of the statistical values. On the receiver side, the shifted histogram can be obtained from both the encrypted image and the decrypted image. Furthermore, the embedded watermark can be extracted from the shifted histogram. The encrypted original image can be restored by employing inverse operations of histogram shifting. This is followed by a decryption operation to restore the original image. In the proposed method, the hidden bits can still be extracted correctly under some typical content-preserving operations, such as JPEG/JPEG2000 compression and additive Gaussian noise. Compared with the previous reversible watermarking methods in plaintext domain, the proposed method has satisfactory performance in image quality and robustness. Experimental results have shown the validity of the proposed method.     

能区分图像或水印篡改的脆弱水印方案

针对现有脆弱型水印方案不能区分是图像内容还是水印被篡改的问题,提出一种能区分图像或水印篡改的脆弱水印方案.该方案用原始图像高7位的小波低频系数非均匀量化后生成的低频压缩图像作为水印,并用混沌系统对水印进行置乱加密,将安全性得到增强的水印直接嵌入到图像的LSB位;认证时通过差值图像定位图像内容被篡改的位置并指出图像中的水印是否被篡改.理论分析和仿真实验表明:该算法不但能精确定位图像内容被篡改的位置,而且能区分是图像内容被篡改、水印被篡改还是两者同时被篡改.     

基于DCT的彩色图像水印算法

提出了一种基于DCT的彩色图像水印算法,通过修改彩色图像绿色分量的DCT系数实现水印的嵌入。原始二值水印图像经Arnold置乱加密后,嵌入到绿色分量的DCT中频系数中,并能够根据原始图像提取出来。实验证明,该算法能有效抵抗JPEG压缩、裁剪、加噪、图像增强等攻击,具有良好的不可感知性和很强的鲁棒性。     

A Block-Level Image Tamper Detection Scheme Using Modulus Function Based Fragile Watermarking

Intentional illegitimate modification in any digital image data is one of the general malversations in the existing digital domain. Therefore in this work, the authors have devised a fragile watermarking technique for the localization of illegitimate modifications in the digital image content effectually. The proposed technique detects forged digital image content strongly in the block-level of two successive pixels. This scheme is performed at the block level, where the actual image is partitioned into non-overlapping blocks of size (1?×?2) pixels. Afterward, the block-level authentication code is generated from the MSB of two successive pixels of each block using averaging and modulus operations. The generated authentication code/watermark is encrypted using a logistic-map-based chaotic key series. The encrypted authentication code is embedded into two successive pixels of the corresponding block. Further, any form of forgery in the watermarked image can be detected by comparing its extracted authentication code and regenerated authentication code. The proposed procedure is successfully experienced on a variety of grayscale images, and the experimental results exhibit that watermarked images generated by this scheme are of considerably high quality in terms of PSNR, IF, and SSIM. The proposed method is capable of efficient forgery detection by achieving very high accuracy, NC, and true positive rate while maintaining considerably low false-positive and false-negative rates.

     

基于匹配滤波的有意义图像水印算法

图像隐形水印是解决数字媒体版权保护的有效手段.目前的大多数水印算法采用伪随机序列构成水印,因而只能给出"Yes"(有水印)或"No"(无水印)的回答.嵌入有意义的水印在一些应用场合更加重要,但同时也带来了更多的困难.嵌入有意义的水印必须解决二个问题:(1)嵌入的水印具有一定的数据量;(2)从有失真的水印图像中正确地提取嵌入的水印.本文应用数字通信的理论和方法,提出了一个嵌入有意义字符串的DCT域隐形水印算法.该算法采用BCH编码和匹配滤波来降低误码率.应用所提出的算法,把一个32个字符组成的水印嵌入到256×256的图像中并达到了较好的稳健性.在水印图像信噪比受Gaussian加性噪声干扰下降到26dB时,仍实现了对嵌入水印零错误概率的检测.     

A secure high capacity full-gray-scale-level multi-image information hiding and secret image authentication scheme via Tchebichef moments

The growth of image processing tools and applications has made it easy for multi-media content such as music, audio, and video to be manipulated or forged during transmission over the Internet. Efforts, such as information hiding in steganography, have been unable to secure data transmission and prevent its manipulation. Usage of coding theory, including cryptography, is not full proof in the sense that an unauthorized intruder may inject (tampering) and incorporate unintended data to the messages, which can tamper the transmitted data. There is a need for more transparent message information hiding schemes along with information content verification and authentication, as well as accurate tampering detection. In particular, as it is well known, in many current steganography methods, widely used for image information hiding, there are various technical challenges associated with hiding large amounts of image information in images. Some of these challenges relate to which locations, in a given carrier image, information has to be hidden in order to guarantee transparency of the resulting watermarked images, to the ability to extract hidden information accurately, to the performance of hidden secret information authentication and verification at the receiving end, to the dependency of the hidden information on a given carrier image, to the robustness of information hiding schemes to affine transformations such as rotation, and to the amount of data and number of full-scale images one can embed in a given single image carrier. Additionally, as it is well known, many of the existing stenography methods are based on the Discrete Fourier Transform (DFT), the Discrete Cosine Directors (DCT), or the Discrete Wavelength Transform (DWT) methods, which result in high Bit Error Rate (BER) of the extracted data. In this paper we present a secure high capacity image information hiding scheme where two full separate arbitrary full-scale gray level images (versus binary), one hidden information image and one authentication watermark image are hidden/embedded in the Tchebichef moments of a carrier image with very high imperceptibility. Here the second watermark image is used for identification and content integrity verification and authentication of the hidden secret image. Both the hidden secret hidden image and the authentication watermark image are of the same size as that of a given arbitrary carrier image. In particular, with the cost of computer memory getting lower and the bandwidth of transmission channels getting larger, we show how three different watermarked images, but the same to a naked eye, are produced and transmitted to achieve the desired advantages of high accuracy, security, authentication and verification of the recovered information. To the best of our knowledge, this two-full-scale gray images data hiding and hidden secret image information verification and authentication method is the first attempt of its sort. We show here the robustness of the proposed scheme to affine transformations such as rotation, scaling, and translation, the proposed scheme's high image malicious tampering detection and tampering localization and its high quality extracted recovered and authenticated hidden secret images. Additionally, in order to as much as possible keep the integrity of the received information, when watermarked images are rotated during transmission, a new image rotation estimation and recovery algorithm is presented as part of the proposed information hiding scheme. We show the effect of intended tampering attacks namely, cropping, noise, low-pass and high-pass filtering on the presented scheme. We also show how the extracted information accuracy is generally independent of the carrier image, and we present a mathematical analysis for characterizing the conditions under which transparency of the hidden embedded information is generally achieved for any given arbitrary carrier image. The case of how to extract the hidden information when one or two of the watermarked images is (are) lost is also tackled. Finally, experimental results on real images are presented to illustrate the efficiency and capabilities of the proposed method.     

数字图像水印嵌入强度的最优估计

提出了一种在数字图像中水印嵌入强度的最优估计方法.对基于一次Bézier曲线融合方式的嵌入规则进行了研究.在水印图像的提取过程中,水印强度因子的选择是基于极大似然估计方法.对基于一次Bézier曲线融合方式的嵌入规则与加法、乘法嵌入规则的峰值信噪比进行比较,可以看出前者嵌入水印的峰值信噪比高于另外两种嵌入方法,人类视觉系统不能发觉嵌入了水印的隐秘图像与原始图像的差别;在不知道嵌入水印强度因子的前提下,可根据对水印强度因子的估计,从隐秘图像中将水印提取出来,而且提取效果令人满意;水印图像由二值图像推广到非二值图像.     

基于混沌序列的DWT域图像水印算法

数字媒体版权保护已经变得十分迫切和必要,有效的盗版确认方法是实现版权保护的前提。本文提出一种基于混沌序列加密的频率域数字图像水印算法,先将二值图像水印信号采用混沌序列加密,然后再通过另外一个混沌序列控制水印嵌入在小波变换域系数中位置,实现小波系数中隐藏不可见水印的技术。实验结果表明,该项技术具有非常好的安全性;水印提取在DWT域中进行,不需要原始图像;该方法嵌入的水印不可见性好,对JPEG-2000压缩、图像剪切和图像加噪声攻击具有较好的鲁棒性。     

Wavelet-based watermarking for color images through visual masking

In this paper, a wavelet-based watermarking scheme for color images is proposed. The watermarking scheme is based on the design of a color visual model that is the modification of a perceptual model used in the image coding of gray scale images. The model is to estimate the noise detection threshold of each wavelet coefficient in luminance and chrominance components of color images in order to satisfy transparency and robustness required by the color image watermarking technique. The noise detection thresholds of coefficients in each color component are derived in a locally adaptive fashion based on the wavelet decomposition, by which perceptually significant coefficients are selected and a perceptually lossless quantization matrix is constructed for embedding watermarks. Performance in terms of robustness and transparency is obtained by embedding the maximum strength watermark while maintaining the perceptually lossless quality of the watermarked color image. Simulation results show that the proposed scheme is more robust than the existing scheme while retaining the watermark transparency.