A novel blind digital watermarking algorithm for embedding color image into color image

A robust and blind watermarking technique for dual color images is proposed in this paper. According to the energy concentrating feature of DCT, the two-level DCT is introduced and used to embed color watermark image into color host image, which is completely different with the traditional DCT. For reducing the redundancy of watermark information, the original color watermark image is compressed by the proposed compression method. After two-level DCT, nine AC coefficients in different positions of each sub-block are selected and quantified to embed watermark information. Moreover, only the extraction rules are used to extract watermark from the watermarked image without resorting to the original host image or watermark image. Experimental results show that the proposed watermarking algorithm can effectively improve the quality of the watermarked image and the robustness of the embedded watermark against various attacks.     

Image watermarking based on an iterative phase retrieval algorithm and sine-cosine modulation in the discrete-cosine-transform domain

A novel digital image watermarking system based on an iterative phase retrieval algorithm and sine-cosine modulation in the discrete-cosine-transform (DCT) domain is proposed. The original hidden image is first encrypted into two phase masks. Then the cosine and sine functions of one of the phase masks are introduced as a watermark to be embedded into an enlarged host image in the DCT domain. By extracting the watermark of the enlarged superposed image and decryption we can retrieve the hidden image. The feasibility of this method and its robustness against some attacks, such as occlusion, noise attacks, quantization have been verified by computer simulations. This approach can avoid the cross-talk noise due to direct information superposition and enhance the imperceptibility of hidden data.     

A novel blind color images watermarking based on SVD

Since the color image watermark has more bit information, it is a challenging problem to design a robust and blind color watermarking scheme for copyright protection. In this paper, a blind watermarking scheme based on singular value decomposition (SVD) is proposed. By analyzing the orthogonal matrix U via SVD, it is found that there exists a strong similarity correlation between the second row first column element and the third row first column element. Hence, this paper utilizes this property for image watermarking. Firstly, the 4 × 4 non-overlapping pixels block of each component in color host image is processed by SVD. And then, the color watermark is embedded by slightly modifying the value of the second row first column element and the third row first column one of U matrix, and the modified relation can be utilized to extract watermark. Experimental results, compared with the related existing methods, show that the proposed color image scheme has stronger robustness against most common attacks such as image compression, filtering, cropping, noise adding, blurring, scaling and sharpening et al.     

基于菲涅耳全息图和离散余弦变换的“盲数字水印”技术

基于光学菲涅耳全息图和相位密码板,结合离散余弦变换,设计了一种新的正实值编码的“盲数字水印”计算方法.相位密码板是多个点光源的菲涅耳衍射光场的相角之和,原始水印图像在其菲涅耳衍射域中与通过相位密码板的参考光作相干叠加,形成菲涅耳全息图;之后将其嵌入到原始宿主图像的离散余弦变换中,同时将此叠加水印信息的原像素值用其邻近的原像素均值来替换;通过作逆离散余弦变换,获得了已嵌入水印信息的正实数值的目标图像;通过对载有水印信息的目标图像作逆运算,从中提取了原始水印图像.数值计算结果表明：该水印计算法对JPEG有损压缩、剪切、噪音污染和重采样等攻击,具有很强的鲁棒性.由于本算法属“盲数字水印”技术,以及水印信息的灵活嵌入和多重密钥（衍射距离、多个点光源位置等）的随意选择,从而使该算法具有很高的安全性和实用价值.     

基于SIFT图像特征区域的全息水印技术

为了增强水印的不可见性和鲁棒性,提出了一种基于图像特征区域的水印算法。首先利用SIFT(Scale Invariant Feature Transform)算法从载体图像蓝色B通道中提取图像特征点来进行优化和筛选,根据优化后的稳定特征点及其特征尺度确定图像的特征区域,再结合全息技术,对原始水印图像进行双随机相位加密,生成加密全息水印;然后对特征区域进行离散余弦变换(DCT);最后在其中频区域嵌入加密全息水印。在提取水印时无须借助原始图像,是盲水印技术。实验结果表明:该算法重建的水印图像与原始水印图像的NC值高达0.95;水印的嵌入对图像质量影响很小,PSNR值高达55.97,能够抵抗常规信号攻击及缩放、剪切、平移等几何攻击。     

分数傅里叶域数字水印算法

基于离散分数傅里叶变换(DFRFT)快速算法发展了一种分数傅里叶谱域图像水印算法.该算法根据分数傅里叶变换谱具有空域和频域双域信息表达能力,分别对原始图像和所加水印信息进行不同级次的分数傅里叶变换,提取水印分数傅里叶谱的低频成分并直接将其叠加到原始图像的分数傅里叶谱中的对角像元上,然后再进行逆变换得到水印图像.在JPEG压缩、图像旋转及剪切等攻击方式下,对该水印算法进行了鲁棒性分析,数值实验表明该水印算法具有良好的抗攻击性和安全性.     

A feature-based robust digital image watermarking scheme using bandelet transform

Desynchronization attacks are among the most difficult attacks to resist, for it can desynchronize the location of the watermark and hence cause incorrect watermark detection. The design of an image watermarking scheme that is robust against desynchronization attacks is challenging. Based on a multi-scale SIFT (scale invariant feature transform) detector and Bandelet transform theory, we propose a new content based image watermarking algorithm with good visual quality and reasonable resistance toward desynchronization attacks. Firstly, the stable image feature points are extracted from the original host by using the multi-scale SIFT detector, and the local feature regions (LFRs) are constructed adaptively according to the feature scale theory. The Bandelet transform is then performed on the LFRs. Finally, the digital watermark is embedded into the LFRs by modifying the significant Bandelet coefficients. By binding the watermark with the geometrically invariant image features, the watermark detection can be done without synchronization error. Experimental results show that the proposed image watermarking is not only invisible and robust against common signal processing such as sharpening, noise adding, JPEG compression, etc., but also robust against the desynchronization attacks such as rotation, translation, scaling, row or column removal, cropping, etc.     

基于双混沌置乱和扩频调制的彩色图像盲水印算法

提出了一种新的适应彩色图像的盲水印算法,先对宿主图像的绿色分量以8×8像素分块进行离散余弦变换(DCT)变换,用logistic映射生成两个混沌序列,然后用混沌序列置乱加密二值水印图像,并用两个互不相关的伪随机序列扩频调制水印,最后将调制好的水印嵌入到DCT变换域的中频子带系数上,进行分块DCT反变换得到水印化图像.提取水印时,通过比较两个伪随机序列和水印化图像的相关性大小来提取水印,不需要原始图像的参与,为盲提取水印算法.实验结果证明本文算法能有效地抵抗JPEG压缩、加噪、剪切等常见攻击,绿色分量嵌入水印比红色和蓝色分量嵌入水印能更好地抵抗JPEG压缩的攻击.     

A color image watermarking scheme based on hybrid classification method: Particle swarm optimization and k-nearest neighbor algorithm

In this paper, a novel robust watermarking technique using particle swarm optimization and k-nearest neighbor algorithm is introduced to protect the intellectual property rights of color images in the spatial domain. In the embedding process, the color image is separated into non-overlapping blocks and each bit of the binary watermark is embedded into the individual blocks. Then, in order to extract the embedded watermark, features are obtained from watermark embedded blocks using the symmetric cross-shape kernel. These features are used to generate two centroids belonging to each binary (1 and 0) value of the watermark implementing particle swarm optimization. Subsequently, the embedded watermark is extracted by evaluating these centroids utilizing k-nearest neighbor algorithm. According to the test results, embedded watermark is extracted successfully even if the watermarked image is exposed to various image processing attacks.     

Embedding color watermarks in color images based on Schur decomposition

In this paper, a blind dual color image watermarking scheme based on Schur decomposition is introduced. This is the first time to use Schur decomposition to embed color image watermark in color host image, which is different from using the binary image as watermark. By analyzing the 4 × 4 unitary matrix U via Schur decomposition, we can find that there is a strong correlation between the second row first column element and the third row first column element. This property can be explored for embedding watermark and extracting watermark in the blind manner. Since Schur decomposition is an intermediate step in SVD decomposition, the proposed method requires less number of computations. Experimental results show that the proposed scheme is robust against most common attacks including JPEG lossy compression, JPEG 2000 compression, low-pass filtering, cropping, noise addition, blurring, rotation, scaling and sharpening et al. Moreover, the proposed algorithm outperforms the closely related SVD-based algorithm and the spatial-domain algorithm.     

A blind dual color images watermarking based on IWT and state coding

In this paper, a state-coding based blind watermarking algorithm is proposed to embed color image watermark to color host image. The technique of state coding, which makes the state code of data set be equal to the hiding watermark information, is introduced in this paper. When embedding watermark, using Integer Wavelet Transform (IWT) and the rules of state coding, these components, R, G and B, of color image watermark are embedded to these components, Y, Cr and Cb, of color host image. Moreover, the rules of state coding are also used to extract watermark from the watermarked image without resorting to the original watermark or original host image. Experimental results show that the proposed watermarking algorithm cannot only meet the demand on invisibility and robustness of the watermark, but also have well performance compared with other proposed methods considered in this work.     

Gray images embedded in a color image and encrypted with FRFT and Region Shift Encoding methods

In this paper, we have proposed a new multiple image encryption and watermarking technique. Several gray images can be watermarked in the three channels of an enlarged color image. The neighbor pixel value addition and subtraction algorithm is used to realize blind watermarking, therefore the original host color image does not need in extraction the watermark image. The gray images are encrypted with FRFT and Region Shift Encoding techniques before hiding to enhance the security. The robustness against occlusion attacks and noise attacks are also analyzed. And some computer simulations are presented to verify the possibility.     

A robust image watermarking technique using SVD and differential evolution in DCT domain

In this paper we applied differential evolution (DE) algorithm to balance the tradeoff between robustness and imperceptibility by exploring multiple scaling factors in image watermarking. First of all, the original image is partitioned into blocks and the blocks are transformed into Discrete Cosine Transform (DCT) domain. The DC coefficients from each block are collected to construct a low-resolution approximation image and apply Singular Value Decomposition (SVD) on this approximation image. After that watermark is embedded by modifying singular values with the singular values of the watermark. The role of DE algorithm is to identify the best multiple scaling factors for embedding process in order to achieve the best performance in terms of robustness without compromising with the quality of the image. To enhance the security, watermark is scrambled by Arnold transform before embedding. Experimental results show that the proposed scheme maintains a satisfactory image quality and watermark can still be identified from a seriously distorted image.     

A novel image tamper localization and recovery algorithm based on watermarking technology

In this paper, an effective self-embedding fragile watermarking scheme is presented. The watermark is generated by encoding the DCT coefficients of each 2 × 2 block and embedded into another block according to the block mapping. A non-linear chaotic sequence is used for generating the block mapping which can enhance the security of the algorithm. An improved tamper localization and recovery algorithm are performed. The experiment results show that the watermarked image has a high average peak signal-to-noise ratio. Furthermore, the tamper region can be successfully localized and exactly recovered, even if for the content-only tampering.     

An optimal adaptive quantization index modulation watermarking algorithm

A novel adaptive watermarking algorithm in discrete wavelet transform （DWT） based on quantization index modulation （QIM） technique is presented. The host image is decomposed into wavelet subbands, and then the approximation subband is divided into non-overlapping small embedding blocks. The secret watermark bit is embedded into singular value vector of each embedding block by applying QIM. To improve the invisibility and robustness of watermarking system, the quantization step for each embedding block is set by combining statistical model with particle swarm optimization （PSO） algorithm. The experimental results show that the proposed algorithm not only preserves the high perceptual quality, but also effectively stands against joint photographic experts group （JPEG） compression, low-pass filtering, noise addition, scaling, and cropping attacks, etc. The comparison analysis demonstrates that our scheme has better performance than the previously reported watermarking algorithms.     

一种基于图象融合的数字水印方法

提出了一种基于多分辨率图象融合的数字水印算法.该算法基本思想源自公开钥加密系统与Torus自同构映射置乱的概念,并根据视觉系统HVS的照度掩蔽特性及组合规则,以原始图象的子波分解级数为依据,对原始图象及水印的子波变换系数进行融合,以实现水印在原始图象空间位置和频率方向上的嵌入.实验结果表明,该算法具有良好的鲁棒性和可行性.     

Improving the performance of DCT-based fragile watermarking using intelligent optimization algorithms

The performance of a fragile watermarking method based on discrete cosine transform (DCT) has been improved in this paper by using intelligent optimization algorithms (IOA), namely genetic algorithm, differential evolution algorithm, clonal selection algorithm and particle swarm optimization algorithm. In DCT based fragile watermarking techniques, watermark embedding can usually be achieved by modifying the least significant bits of the transformation coefficients. After the embedding process is completed, transforming the modified coefficients from the frequency domain to the spatial domain produces some rounding errors due to the conversion of real numbers to integers. The rounding errors caused by this transformation process were corrected by the use of intelligent optimization algorithms mentioned above. This paper gives experimental results which show the feasibility of using these optimization algorithms for the fragile watermarking and demonstrate the accuracy of these methods. The performance comparison of the algorithms was also realized.     

基于虚拟通道技术的数字图像灰度水印算法

根据提出的虚拟通道技术,提出一种在载体中嵌入灰度图像作为水印的数字水印算法.通过修改载体频率域系数,载体通道可被看成一个虚拟的水印通道,它由若干个缺损的水印子通道构成,水印的提取不需要原始载体或原始水印的参与.实验结果表明提出的算法很好地保证了水印的不可见性和稳健性.     

基于图象特征的小波域水印算法

提出一种基于图象特征点的小波变换域第二代水印算法.首先对图象作小波变换,其中最低频成分是图象的粗尺度(低分辨率)逼近,从中提取出图象的特征点;然后在特征点对应的所有高频系数中嵌入水印.水印检验不需要原始图象,但需要原始图象的特征点位置信息,计算特征点对应的所有高频系数与嵌入水印的互相关,利用门限值检验水印是否存在. 实验证明该算法对通常的图象处理有很强的鲁棒性,对有损压缩的鲁棒性尤为突出,而且对几何变换也有一定鲁棒性.     

基于混沌的自嵌入安全水印算法

利用混沌系统的伪随机性和初值敏感性，提出一种基于混沌的自嵌入安全水印算法.该算法以混沌初值为密钥生成混沌序列，根据混沌序列的索引有序序列随机生成图像块的水印嵌入位置.与现有的自嵌入算法相比，该算法实现了水印嵌入位置的随机选取，有效扩大了算法的密钥空间，且解决了自嵌入水印算法如何准确定位篡改块的问题.理论分析和仿真结果表明，该算法不仅提高了自嵌入水印算法的篡改定位的能力，而且进一步增强了算法抵抗向量量化攻击和同步伪造攻击的能力. 关键词： 数字水印 混沌 脆弱水印 自嵌入