一种改进的DCT和SVD联合的数字图像水印算法

结合奇异值分解(SVD)和离散余弦变换(DCT)的特点,本文提出了一种改进的DCT和SVD联合的数字图像水印算法。该算法能够很好地解决透明性和鲁棒性之间的矛盾。算法中按Z字型选取低频系数,再结合SVD分解的方法嵌入水印,不仅增加了嵌入的信息量,而且提高了水印的安全性。实验结果表明,该算法不仅具有较好的透明性,而且对常见攻击如叠加噪声、JPEG压缩、滤波以及几何攻击等具有较好的鲁棒性。     

An adaptive color image watermarking using RDWT-SVD and artificial bee colony based quality metric strength factor optimization

Image watermarking has emerged as a useful method for solving security issues like authenticity, copyright protection and rightful ownership of digital data. Existing watermarking schemes use either a binary or grayscale image as a watermark. This paper proposes a new robust and adaptive watermarking scheme in which both the host and watermark are the color images of the same size and dimension. The security of the proposed watermarking scheme is enhanced by scrambling both color host and watermark images using Arnold chaotic map. The host image is decomposed by redundant discrete wavelet transform (RDWT) into four sub-bands of the same dimension, and then approximate sub-band undergoes singular value decomposition (SVD) to obtain the principal component (PC). The scrambled watermark is then directly inserted into a principal component of scrambled host image, using an artificial bee colony optimized adaptive multi-scaling factor, obtained by considering both the host and watermark image perceptual quality to overcome the tradeoff between imperceptibility and robustness of the watermarked image. The hybridization of RDWT-SVD provides an advantage of no shift-invariant to achieve higher embedding capacity in the host image and preserving the imperceptibility and robustness by exploiting SVD properties. To measure the imperceptibility and robustness of the proposed scheme, both qualitative and quantitative evaluation parameters like peak signal to noise ratio (PSNR), structural similarity index metric (SSIM) and normalized cross-correlation (NC) are used. Experiments are performed against several image processing attacks and the results are analyzed and compared with other related existing watermarking schemes which clearly depict the usefulness of the proposed scheme. At the same time, the proposed scheme overcomes the major security problem of false positive error (FPE) that mostly occurs in existing SVD based watermarking schemes.     

A semi-blind digital watermarking scheme based on singular value decomposition

This paper presents a robust watermarking approach for hiding grayscale watermarks into digital images. Plugging the codebook concept into the singular value decomposition (SVD), the proposed method embeds the singular values (SVs) of the original image into the watermark one to attain the lossless objective. The experimental results show that the proposed scheme guarantees the extracted watermark on an average and the worst PSNR values of 24.91 and 19.96 dB, respectively. In addition to the guarantee of the quality of extracted watermark image, the security of the referenced watermark is further strengthened by applying chaos permutation on it in advance. The proposed scheme leads to satisfactory robustness to various attacks and is compared to other well-known grayscale watermarking methods to reveal its efficiency for practical applications.     

一种基于Slant变换和SVD的稳健性数字水印算法

针对奇异值分解(SVD)存在的虚警错误和水印隐蔽性与鲁棒性的矛盾问题,提出了一种基于Slant变换和SVD的稳健性数字水印算法。对二值水印图像进行Arnold置乱和Logistic映射双因子加密预处理,增强水印信息安全性;将原始载体图像分成8×8不重叠子块分别对其进行Slant变换和块奇异值分解;然后将水印图像SVD后的左奇异矩阵和奇异值矩阵相乘作为水印主成分嵌入到每个子块的最大奇异值中。仿真实验结果表明,该算法不仅有效解决了传统SVD水印算法的虚警问题,提升了运行速度和水印安全性,在具有较好隐蔽性的同时,对JPEG压缩、噪声、滤波、几何攻击等也有较好的稳健性。     

DWT-SVD and DCT based robust and blind watermarking scheme for copyright protection

In this article, a new DWT-SVD and DCT with Arnold Cat Map encryption based robust and blind watermarking scheme is proposed for copyright protection. The proposed scheme solves the most frequently occurring watermarking security problems in Singular Value Decomposition (SVD) based schemes which are unauthorized reading and false-positive detection. This scheme also optimizes fidelity and robustness characteristics. The grey image watermark splits into two parts using four bits MSBs and four bits LSBs of each pixel. Discrete Cosine Transform (DCT) coefficients of these MSBs and LSBs values are embedded into the middle singular value of each block having size 4 × 4 of the host image’s one level Discrete Wavelet Transform (DWT) sub-bands. The reason for incorporating Arnold Cat Map in the proposed scheme is to encode the watermark image before embedding it in the host image. The proposed scheme is a blind scheme and does not require the choice of scaling factor. Thus, the proposed scheme is secure as well as free from the false positive detection problem. The proposed watermarking scheme is tested for various malicious and non-malicious attacks. The experimental results demonstrate that the scheme is robust, imperceptible and secure to several attacks and common signal processing operations.     

基于奇异值分解的、抗几何失真的数字水印算法

许多现有的适用于图像的数字水印对几何失真都是很敏感的。尤其是此类失真会严重妨碍对水印的盲提取。为此，提出了一种基于奇异值分解的数字水印算法，它对常见的几何失真是稳健的。此水印是被嵌入到图像分解后的奇异值之中。根据奇异值分解的代数性质，严格证明了嵌入了水印的图像在受到转置、镜像、旋转、放大和平移等几何失真后，其奇异值是不变的。在经过了上述的几何失真、一般的信号处理操作或JPEG压缩以后，嵌入的水印能够被可靠地提取和检测。实验结果表明本算法具有很好的稳健性。     

基于混沌和SVD DWT的稳健数字图像水印算法*

针对现有适用于图像的数字水印对信号处理和几何失真比较敏感的问题,提出一种稳健的数字图像水印算法。该算法先对整个图像应用三级离散小波变换,再对低频域运用奇异值分解,并通过修改奇异值,嵌入经过混沌置乱的水印图像的奇异值,在小波变换域的中频系数上嵌入水印信息。水印检测时,分别在中频区域和低频提取水印并进行比较,采用效果较好的水印作为检测水印。实验结果表明,该方法对一般的信号处理操作及几何攻击等均具有较好的鲁棒性。     

一种新的基于奇异值分解的小波域盲水印*

目前,如何增强鲁棒性水印抵抗几何攻击尤其是旋转攻击的鲁棒性,仍是水印研究者研究的难点。为此,结合奇异值分解的特性和小波变换的优点,提出一种新的基于奇异值分解的小波域盲水印算法,对于常见的几何攻击具有很强的鲁棒性。首先对小波分解后的低频子带分块以提高水印的嵌入容量,再对各子块进行奇异值分解,将Arnold置乱后的水印嵌入到奇异值中,并使用量化方法增强水印的鲁棒性。实验表明,该算法对于常见的几何攻击特别是旋转攻击具有很强的鲁棒性,也能够抵抗JPEG2000压缩等信号处理。     

Adaptive and blind watermarking scheme based on optimal SVD blocks selection

To protect the ownership of the digital products, a novel adaptive and blind watermarking scheme is designed. Firstly, the underlying reason of image quality degradation in singular value decomposition (SVD)-based watermarking scheme is analyzed and the potential scenario causing visible destroy is pointed out. Then the optimal SVD blocks selection strategy is proposed to improve the imperceptibility. Different from other block selection rules devised by subjective evaluation means, our selection rule aims to retain the image quality as much as possible from the source. Furthermore, information entropy is utilized to achieve the purpose of adaptive embedding. In the experiment, the proposed watermarking scheme is tested under several attacks, such as noise attack, JPEG compression, blurring, sharping, and etc. Finally, the proposed watermarking scheme is compared with other existing schemes, and the experimental results demonstrate the robustness, imperceptibility and superior of the proposed watermarking scheme.

     

基于NMF和SVD相结合的Contourlet域鲁棒水印算法*

为了提高变换域数字水印技术的鲁棒性,提出了一种在Contourlet域将非负矩阵变换(NMF)与奇异值变换(SVD)相结合的鲁棒水印算法。宿主图像经过Contourlet变换后,对低频子带进行非负矩阵变换,然后对非负基向量组W进行奇异值分解,最后将经过Arnold置乱的水印图像嵌入到奇异值中。实验结果表明,该图像水印算法在获得良好视觉效果的同时,对于加噪声、滤波、剪切等图像攻击有较好的鲁棒性。     

An adaptive watermarking scheme for e-government document images

This paper proposes an adaptive watermarking scheme for e-government document images. The adaptive scheme combines the discrete cosine transform (DCT) and the singular value decomposition (SVD) using luminance masking. As a core of masking model in the human visual system (HVS), luminance masking is implemented to improve noise sensitivity. Genetic algorithm (GA), subsequently, is employed for the optimization of the scaling factor of the masking. Involving a number of steps, the scheme proposed through this study begins by calculating the mask of the host image using luminance masking. It is then continued by transforming the mask on each area into all frequencies domain. The watermark image, following this, is embedded by modifying the singular values of DCT-transformed host image with singular values of mask coefficient of host image and the control parameter of DCT-transformed watermark image using Genetic Algorithm (GA). The use of both the singular values and the control parameter respectively, in this case, is not only to improve the sensitivity of the watermark performance but also to avoid the false positive problem. The watermark image, afterwards, is extracted from the distorted images. The experiment results show the improved adaptive performance of the proposed scheme is in resistant to several types of attacks in comparison with the previous schemes; the adaptive performance refers to the adaptive parameter of the luminance masking functioned to improve the performance or robustness of an image from any attacks.     

基于整数小波变换和SVD的视频水印算法

提出了一种以二值图像为水印的混合整数小波变换和奇异值分解的视频水印盲提取算法。对水印图像进行混沌加密和Arnold置乱处理,选择计算复杂度低的直方图算法将视频分割为若干场景;借助密钥随机选取某些场景的亮度分量进行l级整数小波变换,再对低频子带进行分块的奇异值分解;采用量化的方法,将预处理后的水印图像嵌入奇异值分解后的最大奇异值中。在嵌入了水印的视频场景中提取所有的水印版本之后,利用对提取的所有水印信号版本进行统计求和的方法得到最终提取的水印图像。实验表明,提出的算法具有较好的透明性,对常见的处理具有较好的鲁棒性。     

A novel hybrid of DCT and SVD in DWT domain for robust and invisible blind image watermarking with optimal embedding strength

To optimize the tradeoff between imperceptibility and robustness properties, this paper proposes a robust and invisible blind image watermarking scheme based on a new combination of discrete cosine transform (DCT) and singular value decomposition (SVD) in discrete wavelet transform (DWT) domain using least-square curve fitting and logistic chaotic map. Firstly cover image is decomposed into four subbands using DWT and the low frequency subband LL is partitioned into non-overlapping blocks. Then DCT is applied to each block and several particular middle frequency DCT coefficients are extracted to form a modulation matrix, which is used to embed watermark signal by modifying its largest singular values in SVD domain. Optimal embedding strength for a specific cover image is obtained from an estimation based on least-square curve fitting and provides a good compromise between transparency and robustness of watermarking scheme. The security of the watermarking scheme is ensured by logistic chaotic map. Experimental results demonstrate the better effectiveness of the proposed watermarking scheme in the perceptual quality and the ability of resisting to conventional signal processing and geometric attacks, in comparison with the related existing methods.     

基于离散小波—奇异值分解的多水印嵌入算法

为提高传统数字图像水印算法的安全性, 解决数字水印对信号处理和几何失真比较敏感的问题, 提出一种新的以离散小波多级分解与奇异值分解相结合的数字图像水印算法. 不同于常见的基于小波变换的数字水印技术, 该方案在原始图像离散小波变换的低频近似区域和高频对角区域中嵌入水印, 在图像的保真度和鲁棒性之间取得较好的折衷. 水印检测时, 将从低频近似区域和高频对角区域中提取出的水印进行比较, 选择效果较好的水印作为最终检测水印. 实验结果表明, 提出的多水印算法对于各种攻击具有较强的鲁棒性.     

增强奇异值分解和细胞神经网络的零水印

目的 针对奇异值分解算法存在的对角线失真、虚警错误等问题,引入一个寻找最抗攻击缩放比例的参数,提出基于增强奇异值分解的零水印算法。方法 首先将离散小波变换作用于原始图像,对分离出的低频逼近子图进行不重叠分块,对分块后的低频逼近子图作离散余弦变换得到低频系数矩阵,再分别对每个块矩阵进行增强奇异值分解,将得到的最大奇异值与最大奇异值均值作比较构成特征向量;然后对水印图像进行Arnold变换和Logistic映射得到置乱加密后的水印图像;最后将特征向量和置乱加密后的水印图像分别作为细胞神经网络的起始值和控制输入值,通过设定细胞神经网络的反馈模板、控制模板以及阈值来确定具体的可逆逻辑运算。经过可逆逻辑运算处理后的细胞神经网络输出图像即为零水印的注册图像。将注册图像保存到认证中心以证明对图像作品的版权。结果 在JPEG压缩、噪声、滤波、旋转以及剪切等各种攻击下,提取的水印和原始水印的归一化相关值都在96%以上,算法平均运行时间为2.389 s,性能较高。结论 通过利用参数对奇异值矩阵进行调整的方法,不仅增强了算法的鲁棒性,而且解决了奇异值分解（SVD）出现的对角线失真和虚警错误问题。同时通过结合零水印的思想,解决了传统水印算法需在载体图像中嵌入水印而导致的水印不可见性与鲁棒性之间的矛盾。     

局部化数字水印算法

数字水印是一种嵌入到图象,视频或音频数据中的不可见标志,可以用于多媒体数字的版权保护,认证和标注等,为了提高在频率域嵌入水印抵抗裁剪攻击的能力,提出一种局部化的图象数字水印算法,该算法利用图象中相对稳定的特征点标示水印嵌入的位置,并在与每个特征点对应的局部区域中独立地嵌入水印,这样,当只有部分图象时,仍能通过这些特下点来定位并提取水印,此算法中,水印的嵌入是在局部图象的小波域中进行的,并采用对小波系数进行特殊量化的方法来隐藏水印比特,而水印的提取不需要原始图象参与,实验结果证明,算法对裁剪有很强的抵抗能力,同时对压缩,滤波,噪声,StirMark攻击等也有较好的鲁棒性。     

基于角点检测和奇异值分解的多重数字水印算法

针对多媒体数据的版权保护和完整性认证的多方性,提出一种基于角点检测和奇异值分解的多重数字水印算法．本算法将鲁棒水印嵌入到小波域低频子带角点中,将半脆弱水印嵌入到小波域分块细节子带奇异值中,实验仿真结果表明,水印算法能够抵抗剪切、涂改、滤波、压缩等常见攻击,同时也能够抵抗旋转、缩放等几何攻击,具有较好的鲁棒性和脆弱敏感性,且准确定位篡改区域,可谓一种有效的多重数字水印方案．     

An image authentication scheme based on digital watermarking and image secret sharing

This paper presents an image authentication scheme that can verify the origin of the received image and, moreover, detect if the image has been tampered with. The underlying technologies of the scheme are digital watermarking and image secret sharing. Different from other schemes that use one piece of watermark information for one purpose and a different piece for another, the watermark information used for original verification is also utilized for tamper detection. Moreover, unlike other schemes that employ a fixed strength value for embedding watermarks, the scheme automatically utilizes two different strength values, one for flat regions and the other for complex regions. The experimental results prove that using different strength values increases the robustness of the watermark with little sacrifice in image quality. The results also demonstrate the effectiveness of the scheme for the origin verification as well as the tamper detection.     

Attacking visible watermarking schemes

Visible watermarking schemes are important intellectual property rights (IPR) protection mechanisms for digital images and videos that have to be released for certain purposes but illegal reproductions of them are prohibited. Visible watermarking techniques protect digital contents in a more active manner, which is quite different from the invisible watermarking techniques. Digital data embedded with visible watermarks will contain recognizable but unobtrusive copyright patterns, and the details of the host data should still exist. The embedded pattern of a useful visible watermarking scheme should be difficult or even impossible to be removed unless intensive and expensive human labors are involved. In this paper, we propose an attacking scheme against current visible image watermarking techniques. After manually selecting the watermarked areas, only few human interventions are required. For watermarks purely composed of thin patterns, basic image recovery techniques can completely remove the embedded patterns. For more general watermarks consisting of thick patterns, not only information in surrounding unmarked areas but also information within watermarked areas will be utilized to correctly recover the host image. Although the proposed scheme does not guarantee that the recovered images will be exactly identical to the unmarked originals, the structure of the embedded pattern will be seriously destroyed and a perceptually satisfying recovered image can be obtained. In other words, a general attacking scheme based on the contradictive requirements of current visible watermarking techniques is worked out. Thus, the robustness of current visible watermarking schemes for digital images is doubtful and needs to be improved.     

一种改进的DWT-SVD域参考水印方案

针对一类SVD域图像水印方案存在过高虚警概率的问题,提出了一种改进的混合DWT和SVD的图像参考水印算法。算法先对载体图像进行[n]层的离散小波变换,然后随机选取第[n]层的部分或全部子带形成参考子带,并对参考子带进行SVD分解;将Arnold置乱处理后的水印嵌入到SVD分解后的奇异值矩阵中。实验表明,提出的算法具有较好的透明性和安全性;与其他方案相比,解决了虚警概率问题,且对于大部分的攻击,具有更好的鲁棒性能。