一种基于图像最高有效位构造密钥的零水印算法

本文提出一种基于最高有效位(MSB)构造密钥的零水印算法,先将二值水印图像置乱并拓展为载体图像的大小,再将其像素值与载体像素的MSB进行对应比较,当比较结果为真时,用一个零矩阵来标记载体像素的位置,被标记过的零矩阵作为密钥来检测水印。由于水印信息遍布载体图像的MSB而且不改变载体图像的信息,使得算法表现出较好的抗攻击性能。实验表明了该算法的有效性。     

一种基于混沌变换的自适应盲水印

提出一种基于混沌变换技术的双密钥小波域图像数字水印算法,首先利用其中一个密钥产生一个随机数子,用来决定对小波变换后的载体图像的哪一个方向做进一步多分辨分解,确定嵌入水印的位置;然后利用另一密钥对二值水印图像进行随机置乱;根据嵌入位置的自带的自身特点,计算出三个阈值s、s1和s2,将经过随机置乱处理的含版权信息的二值水印图像嵌入到将水印嵌入到水平、垂直和对角方向的子带.在水印检测过程中,提出一种不需要载体图像相关信息的盲检测水印算法.首先根据其中一个密钥找到水印所在的位置,同样计算出相应的s*、s*1和s*2,然后再用另一个密钥重构水印图像.实验证明,提出的水印方案具有较好的抗攻击性,使用双密钥具有很好的安全性.     

基于ZUC可分离加密图像可逆水印算法

本文基于祖冲之(ZUC)算法,设计实现了一种可分离加密图像可逆水印算法,算法中内容所有者先进行图像标记并生成位置图,然后使用ZUC加密算法加密载体图像;水印嵌入者得到加密图像后根据位置图将水印信息嵌在选中像素的第7位或第8位;接收者根据加密密钥和嵌入密钥可以得到直接解密图像、水印信息和恢复图像.算法使用ZUC算法对图像进行加解密,很好地保证算法的安全性;在嵌入水印信息之前对图像进行标记,将水印信息嵌在选中的位置上;接收者在利用相邻像素相关性基础上通过一种自适应差值算法实现水印提取和图像恢复,保证恢复的载体图像和直接解密图像的质量.实验表明所提出的算法具有较高的安全性并且达到可分离的效果,同时恢复的载体图像和直接解密图像都具有较高质量.     

一种基于MSB构造密钥的零水印算法

提出一种基于最高有效位(Most Significant Bit)构造密钥的零水印算法。先将二值水印图像置乱并扩展为载体图像的大小,再将其像素值与载体像素的MSB进行对应比较,当比较结果为真时,用一个零矩阵来标记载体像素的位置,被标记过的零矩阵作为密钥来检测水印。由于水印信息遍布载体图像的MSB而且不改变载体图像的信息,使得算法表现出较好的抗攻击性能。通过与文献[4]“一种基于混沌阵列的鲁棒零水印算法”的比较实验,表明了该算法的有效性。     

基于压缩感知的图像盲水印算法

针对现代数字水印的设计要求,结合压缩感知理论,提出一种图像盲水印算法。该算法利用自然载体图像在小波域中稀疏的特性,将加密后的水印嵌入载体图像离散小波变换系数中。提取水印时, 无需原始载体图像或其他先验知识,根据向量空间、矩阵方程的一些性质,以及压缩感知的重构算法,只需一个密钥(随机数种子)即可从嵌有水印的载体图像中精确提取水印并重构原始载体图像。实验证明,该水印算法具有良好的特性,能够满足实际应用的要求。     

基于非负矩阵分解的图像水印算法

提出一种基于非负矩阵分解NMF(Non-negative Matrix Factorization)的数字水印算法.先通过NMF构造载体图像基于部分表示的系数矩阵,将灰度水印图像嵌入其中;再利用NMF基矩阵作为密钥提取水印.为了说明有效性,该算法与主流的DCT水印算法进行相关比较实验,结果表明该算法同DCT算法一样有效,且在抗剪切和抗滤波性能上优于DCT算法.     

小波域视觉密码零水印算法

目的传统零水印算法需要构造包含图像特征的水印数据,这样构造的水印往往是无意义的。在已有视觉密码鲁棒水印算法基础上,结合零水印思想,提出小波域视觉密码零水印算法。方法零水印不仅仅是由载体图像生成的,而是其与水印信息共同制造的视觉秘密图份。算法产生2幅图份:主图份(图像特征信息)和所有权图份(零水印)。首先,将载体图像通过合理置乱,去除像素相关性;其次,对置乱后的图像做小波变换,再将小波低频子带分块并对各块做奇异值分解,通过比较块特征值与块特征值均值生成过渡矩阵;然后,将生成的过渡矩阵结合2×2视觉秘密图份算法生成主图份;最后,结合主图份和秘密水印信息产生所有权图份,同时将其保存到认证中心。结果针对零水印信息不够直观,在不对载体进行任何改动的情况下,将有意义二值图像作为零水印嵌入到载体图像中去。即使在很强的鲁棒干扰环境中,本文方法仍然比传统的零水印算法表现出色。结论提出了一种可靠的图像版权认证零水印算法。实验结果表明,算法具有良好的安全性,同时对多种图像处理具有很好的鲁棒性。     

基于Turbo码的数字水印方案

提出一种基于Turbo码数字水印方案。该算法既对水印图像进行编码，又对载体图像进行编码。编码数据在经过较低信噪比的信道传输后，由解码算法能同时恢复水印和载体图像。不同于传统数字水印方法，本文方案要求接收用户掌握Turbo解码密钥，方能正确恢复水印和载体图像。本文给出了方案设计流图，然后给出仿真实验结果，仿真结果表明算法在通信中保护水印和载体图像方面是可行的。     

衡平矩阵预处理数字水印

衡平矩阵具有元素的内在冗余性和平衡状态一定程度的稳定性,所以提出将其应用于水印的预处理,从而形成新的水印算法.算法首先将水印进行加密处理,然后将其转变为衡平矩阵,进而将衡平矩阵嵌入到栽体图像.通过对水印的预处理,能实现水印分级提取:既能提取出衡平矩阵,进而在密钥已知的情况下提取出私有水印;另外衡平矩阵的元素冗余性和其平衡状态的稳定性提高了各自级别检测的鲁棒性.进行的仿真实验验证了这种预处理方法的正确性.     

基于关系的DCT域盲水印算法

为了更好进行版权保护,提出一种基于关系的DCT域盲提取数字水印算法。首先,对原始图像进行8×8分块的离散余弦变换,根据变换后每一块内的直流系数和中频系数的关系得到一个极性矩阵,将该极性矩阵与最佳置乱处理后的二值水印图像进行对比,根据对比的结果对载体图像的中频系数进行修改达到水印嵌入的目的。在水印的提取过程中不需要原始图像,实现了水印的盲提取。大量的仿真实验结果表明了该算法的有效性。     

Multiuser-based shadow watermark extraction system

A new watermarking scheme having the ability of sharing secret with multi-users is proposed. It splits the original watermark into two shares and embeds one share into the cover image to increase the security. A polarization procedure is performed to establish a polarity stream from the cover image. The second share and the polarity stream are used to generate a master key and several normal keys. In this system, only the super-user can reveal the genuine watermark directly. Other users possess the normal keys can obtain shadow watermarks merely. By combining the shadow watermarks together, the real watermark can be recovered.     

An efficient lossless robust watermarking scheme by integrating redistributed invariant wavelet and fractional Fourier transforms

An ensemble lossless watermarking scheme is proposed in the present study by integrating different concepts like redistributed invariant wavelet transform, discrete fractional Fourier transform, singular value decomposition (SVD) and visual cryptography within the framework of a single algorithm. The invariant wavelet transform helps to obtain the transform domain, which is invariant to flipping and rotation of image, this is followed by discrete fractional Fourier transform to obtain the translation invariant domain. Finally, embedding positions are selected based on a key and reliable features are extracted by performing SVD on a window centered at these positions. Based on these reliable features a binary map is generated through which a master share is created. The corresponding ownership share is produced from the master share and the watermark. In verification process the same operations of the embedding process are applied to the test image to obtain the master share and the watermark is recovered by stacking it over the ownership share. There are two main features of the proposed scheme (1) The quality of the image to be watermarked do not degrade during the process and (2) the extracted watermark can still be identified even from a seriously distorted image. These findings are also demonstrated with the help of a comparative study with several related schemes.     

A hybrid DWT-SVD copyright protection scheme based on k-means clustering and visual cryptography

In this paper, a novel copyright protection scheme that combines the discrete wavelet transform (DWT) and the singular value decomposition (SVD) is proposed. Instead of modifying the original host image to conceal a secret image, the proposed scheme first extracts the image features from the host image by applying the DWT and the SVD. The extracted features are then classified into two clusters by employing the k-means clustering technique, and a master share is generated using the clustering result. Finally, the master share is used together with a secret image to construct an ownership share according to a two-out-of-two visual cryptography (VC) technique. When rightful ownership needs to be determined, the secret image for ownership identification can be revealed by stacking the master share and the ownership share. Experimental results demonstrate that the proposed scheme can effectively resist several common attacks. In addition, the revealed watermark can be easily recognized by human eyes, even if the host image has undergone severe attacks.     

Digital watermarking using Hall property image decomposition method

Most of the existing singular value decomposition-based digital watermarking methods are not robust to geometric rotation, which change the pixels’ locations without maintaining the corresponding changes to the pixel’s intensity values of entire image and yield high computational cost. To answer this, we propose a digital image watermarking algorithm using the Hall property. In the proposed method, a digital watermark image is factorized into lower-triangular, upper-triangular, and permutation matrices. The permutation matrix is used as the valid key matrix for authentication of the rightful ownership of the watermark image. The product of the lower and upper triangular matrices is processed with a few iterations of the Arnold transformation to obtain the scrambled data. The scrambled data are embedded into particular sub-bands of a cover image using Wavelet transform. Our experiments show that the proposed algorithm is highly reliable and computationally efficient compared with state-of-the-art methods that are based on singular value decomposition.     

An image copyright protection scheme by encrypting secret data with the host image

In this paper, a zero-watermarking based copyright protection scheme is proposed. The secret watermark image is not embedded in the host image rather it is encrypted with the host image. The proposed scheme is making use of discrete cosine transform and singular value decomposition to extract robust features of the host image. Further the selected robust features are used to encrypt the secret image. The secret image is encrypted with the host image by generating two shares namely master share and ownership share. The master share is generated by differential classification of features extracted. The ownership share is generated with the help of master share and the secret image. The two shares separately don’t give any clue of the secret image but when stacked together the encrypted secret image is revealed. Experimental study is conducted to evaluate the robustness of the algorithm against various signal processing and geometrical attacks.     

Size-invariant extended visual cryptography with embedded watermark based on error diffusion

A (2, 2) extended visual cryptography scheme with meaningful shares and no pixel expansion is constructed in this paper. In addition to the secret image, an additional watermark is also embedded to serve for authentication purpose. This watermark can be recovered by stacking a shifted version of one share with the other share. More importantly, the recovered watermark and secret images are free from interferences from the cover images.     

Imperceptible digital watermarking scheme in multiple transform domains

A novel imperceptible digital watermarking scheme in multiple transform domains is presented, where the cover image is dealt with by discrete wavelet transform (DWT), discrete cosine transform (DCT) and discrete fractional random transform (DFRNT), while the watermark image is scrambled by Arnold transform and logistic map. First the watermark is scrambled by the Arnold transform, then the row and the column of the resulting watermark are scrambled by the Logistic map, respectively. In addition, four sub-band images are generated from the host image by the two-dimensional discrete wavelet transform. The low-frequency sub-band images are divided into 8?×?8 small matrices, and a coefficient matrix is produced by performing the discrete cosine transform on each matrix. An intermediate matrix with the same size as the watermark image is constructed by the intermediate frequency coefficients. Then the discrete fractional random transformation is performed on the intermediate frequency coefficient matrix and the scrambled watermark is embedded into the discrete fractional random transformation domain. Compared with the previous schemes, the proposed digital watermarking scheme has stronger imperceptibility and robustness.     

浅析数字水印技术在新闻发布系统中的应用

为了发布信息及时,便于用户快速浏览,开发了一个新闻发布系统信息化平台。该系统采用Visual Studio 2010与Sql Server2008进行开发,基于B/S架构。系统采用了一个关键技术——数字水印技术,将数字水印直接嵌入到新闻发布系统图片信息中,是新闻图片版权保护的重要手段。     

一种基于图像特征区域的数字水印系统

该文提出了一种基于载体图像特征区域的强壮数字图像水印算法。采用边缘识别和人工选择的方法标记出载体图像的特征区域,将水印信号嵌入该特征区域中,在水印嵌入时利用图像的HVS特性使水印强度具有自适应调节特性。水印检测算法还可加入自动校正模块,可大大提高判决的准确性。实验表明该算法具有较好的透明性和强壮性,水印检测结果准确,并且算法复杂度较低。