极坐标下的空域水印算法研究

由于空间域嵌入的水印对旋转和缩放攻击相当脆弱,本文提出一种新的水印算法。将原图像和水印图像进行对数极变换,将变换后的水印图像嵌入到变换后的原图像中,然后再反变换为直角坐标系下的图像。水印嵌入到图片的位置不同,检测的水印图像发生变化。本文提出三种嵌入位置的方案,显示不同的效果。检测水印时,对几何攻击过的水水印进行几何校正,然后与原图像相减得到水印。这种水印方案能够很好地抵抗几何攻击。     

A new robust and secure digital image watermarking scheme based on the integer wavelet transform and singular value decomposition

In this paper, a new robust and secure digital image watermarking scheme that can be used for copyright protection is proposed. The scheme uses the integer wavelet transform (IWT) and singular value decomposition (SVD). The grey image watermark pixels values are embedded directly into the singular values of the 1-level IWT decomposed sub-bands. Experimental results demonstrate the effectiveness of the proposed scheme in terms of robustness, imperceptibility and capacity due to the IWT and SVD properties. A challenge due to the false positive problem which may be faced by most of SVD-based watermarking schemes has been solved in this work by adopting a digital signature into the watermarked image. The proposed digital signature mechanism is applied to generate and embed a digital signature after embedding the watermarks; the ownership is then authenticated before extracting watermarks. Thus, the proposed scheme achieved the security issue where the false positive problem is solved, in addition to that, the scheme is considered as a blind scheme. A computer simulation is used to verify the feasibility of the proposed scheme and its robustness against various types of attacks and to compare it with some previous schemes. Furthermore, the statistical Wilcoxon signed rank test is employed to certify the effectiveness of the proposed scheme.     

A secure fragile watermarking scheme based on chaos-and-hamming code

In this work, a secure fragile watermarking scheme is proposed. Images are protected and any modification to an image is detected using a novel hybrid scheme combining a two-pass logistic map with Hamming code. For security purposes, the two-pass logistic map scheme contains a private key to resist the vector quantization (VQ) attacks even though the embedding scheme is block independent. To ensure image integrity, watermarks are embedded into the to-be-protected images which are generated using Hamming code technique. Experimental results show that the proposed scheme has satisfactory protection ability and can detect and locate various malicious tampering via image insertion, erasing, burring, sharpening, contrast modification, and even though burst bits. Additionally, experiments prove that the proposed scheme successfully resists VQ attacks.     

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.     

An efficient and robust watermarking approach based on single value decompression,multi-level DWT,and wavelet fusion with scrambled medical images

This paper offers a medical image watermarking approach based on Wavelet Fusion (WF), Singular Value Decomposition (SVD), and Multi-Level Discrete Wavelet Transform (M-DWT) with scrambling techniques for securing the watermarks images. The proposed approach can be used for providing multi-level security in various applications such as military, copyright protection, and telemedicine systems. The key idea of the projected approach is to first combine two digital watermark images into a single fused watermark to increase the embedded information payload. Then, the fused watermark is scrambled using Arnold and Chaotic algorithms. Finally, the scrambled fused watermark is embedded in the cover image using the SVD and three-level DWT algorithms. The selection of the Arnold and chaotic for watermark encryption is attributed to confirm robustness which resists several types of multimedia attacks and upturn the security level. This paper also presents a comparative study of the proposed approach for different digital images to determine its robustness and stability. Several simulation results reveal that the proposed system improves the capacity and security of embedded medical watermarks without affecting the cover image quality. In conclusion, the proposed approach achieved not only precise acceptable perceptual quality with admired Peak Signal-to-Noise Ratio (PSNR) values but similarly high Correlation Coefficient (Cr) and SSIM values in the existence of severe attacks.

     

A multimodal biometric watermarking system for digital images in redundant discrete wavelet transform

The traditional watermarking algorithms prove the rightful ownership via embedding of independent watermarks like copyright logos, random noise sequences, text etc into the cover images. Coupling biometrics with watermarking evolved as new and secure approach as it embeds user specific biometric traits and thus, narrows down the vulnerability to impostor attacks. A multimodal biometric watermarking system has been proposed in this paper in the redundant discrete wavelet transform(RDWT). Two biometric traits of the user i.e. the iris and facial features are embedded independently into the sub-bands of the RDWT of cover image taking advantage of its translation invariant property and sufficient embedding capacity. The ownership verification accuracy of the proposed system is tested based on the individual biometric traits as well as the fused trait. The accuracy was enhanced while using the fused score for evaluation. The security of the scheme is strengthened with usage of non-linear chaotic maps, randomization via Hessenberg decomposition, Arnold scrambling and multiple secret keys. The robustness of the scheme has been tested against various attacks and the verification accuracy evaluated based on false acceptance rate, false rejection rate, area under curve and equal error rate to validate the efficacy of the proposed scheme.

     

结合汉明码和图像矫正的彩色图像盲水印

目的 随着互联网技术的飞速发展,彩色数字图像带来极大便利的同时,也产生了一些篡改、剽窃等侵权行为;同时,几何处理对含水印载体的破坏使水印盲检测的难度增加,因此,本文提出一种基于汉明码和图像矫正的彩色图像盲水印方法,旨在解决当前图像版权保护的难点问题。方法 嵌入水印时,使用仿射变换加密彩色水印,并将已加密的信息编为汉明码,然后利用特征值分解计算出像素块的全部特征值,并通过对特征值绝对值的和进行量化来完成水印的嵌入;提取水印时,利用图像的几何属性对多种几何攻击后的图像进行判断、矫正,并借助量化技术提取水印。结果 基于彩色图像标准数据库,将本文方法与7种相关方法进行了对比实验：在不可见性方面,与LU分解的水印方法相比,本文算法峰值信噪比（peak signal-to-noise ratio,PSNR）提高了4 dB;在常规攻击鲁棒性方面,与Schur分解的最新方法相比,本文算法平均归一化互相关（normalized cross-correlation,NC）的值稍有提高;在几何攻击鲁棒性方面,本文算法NC值具有一定的优势;同时,本文算法的水印容量达到了0.25 bit/像素,密钥空间达到了2⁴³²,运行时间仅需3 s左右。结论 所提方法不仅具有较好的水印不可见性和较强的鲁棒性,而且具有较大的水印容量、较高的安全性和实时性。     

基于多重元胞自动机的图像水印加密算法

针对目前基于直方图平移类可逆水印算法存在的安全问题, 提出一种基于多重元胞自动机(Cellular automata, CA)的图像水印加密算法. 该算法综合考虑辅助信息、水印及水印图像三方面的安全性, 利用不同的元胞自动机规则进行逐级加密, 建立多重加密模型生成加密水印图像. 仿真结果表明, 该算法在密钥空间、直方图分布、相关性、信息熵及灰度变化等安全评估标准下均具有较高的安全性, 有效克服了基于直方图平移类可逆水印算法在安全性方面存在的不足.     

Highly Robust, Secure, and Perceptual-Quality Echo Hiding Scheme

Audio watermarking using echo hiding has fairly good perceptual quality. However, security and the tradeoff between robustness and imperceptibility are still relevant issues. This paper presents the echo hiding scheme in which the analysis-by-synthesis approach, interlaced kernels, and frequency hopping are adopted to achieve high robustness, security, and perceptual quality. The amplitudes of the embedded echoes are adequately adapted during the embedding process by considering not only the characteristics of the host signals, but also cases in which the watermarked audio signals have suffered various attacks. Additionally, the interlaced kernels are introduced such that the echo positions of the interlaced kernels for embedding "zero" and "one" are interchanged alternately to minimize the influence of host signals and various attacks on the watermarked data. Frequency hopping is employed to increase the robustness and security of the proposed echo hiding scheme in which each audio segment for watermarking is established by combining the fractions selected from all frequency bands based on a pseudonoise sequence as a secret key. Experimental results indicate that the proposed analysis-by-synthesis echo hiding scheme is superior to the conventional schemes in terms of robustness, security, and perceptual quality.     

Multiresolution fragile watermarking using complex chirp signals for content authentication

This paper proposes a wavelet-domain multiresolution fragile watermarking scheme using an improved quantization-index-modulation (QIM) embedding technique. A secure embedding zone is exploited in our proposed scheme to reduce the false detection rate of Kundur's scheme. The frequency modulated (FM) complex chirp signal is employed as watermark. Both the real and the imaginary parts of the chirp signal are embedded simultaneously in a hierarchical manner. Unlike the conventional schemes, the proposed scheme does not require the original watermark for content integrity verification and quality assessment for the distorted watermarked content. The blind authentication process allows embedding of arbitrary FM chirp watermarks.     

安全高效的水印认证协议

基于完全零知识交互证明系统和位委托方案,提出了可证明的安全水印认证协议.现有文献大都使用基于Cox的扩频数字水印方案或对其进行修改后的扩频水印方案.采用了鲁棒性较强的更适合于版权保护的乘法嵌入规则,在宿主信号中嵌入水印;水印检测时,在充分考虑了不同的变换域、信道特性以及人类视觉特性的基础上,采用基于广义高斯分布和Weibull分布模型的各种变换域的鲁棒优化检测器.使用位委托方案对数字水印信息进行委托,并联合使用随机序列隐藏水印嵌入位置信息.协议确保了在证明相应水印存在的同时,没有泄露任何有关水印的敏感信息,防止了蓄意攻击者利用认证过程中泄露的有关水印的敏感信息(如水印、水印位置、提取密钥等)来移除或伪造水印.数字水印方案对各种变换域的水印检测器给予了较全面的考虑,所以,应用该协议进行水印认证,其安全性、有效性、鲁棒性和实用性都有较大提高.     

彩色数字图像的脆弱数字水印

针对彩色数字图像局部区域内容保护和认证,研究了彩色数字图像的脆弱数字水印.为了保证水印的安全性,利用三维二值混沌序列对原始二值水印图像进行加密,对提取的加密二值水印图像进行解密.嵌入载体图像的水印和从嵌入水印的图像中提取的水印均是加密水印.将彩色数字图像中被保护区域的三个分量的小波变换域分别嵌入加密水印,以保护其内容的完整性和不可篡改性.采用模运算实现水印的嵌入和盲提取.理论分析和实验结果表明,该脆弱水印算法对彩色数字图像保护区域内的任何篡改,都能够正确地检测和定位.     

基于多尺度知识学习的深度鲁棒水印算法

针对现有基于深度学习框架的水印算法无法有效保护高维医学图像版权问题,提出一种基于多尺度知识学习的医学图像水印算法用于弥散加权图像的版权保护。首先,提出一个基于多尺度知识学习的水印嵌入网络来嵌入水印,并通过微调的预训练网络提取弥散加权图像的语义、纹理、边缘以及频域信息作为多尺度的知识特征;然后,结合多尺度的知识特征来重构弥散加权图像,并在该过程中冗余地嵌入水印,从而获得视觉上与原始图像高度相似的含水印的弥散加权图像;最后,提出一个基于金字塔特征学习的水印提取网络,并通过在含有水印的弥散加权图像的不同尺度的上下文中学习水印信号的分布相关性来提高算法的鲁棒性。实验结果表明,所提算法重构出的含水印图的平均峰值信噪比（PSNR）达到57.82 dB。由于弥散加权图像在转换为弥散张量图像时需满足一定的弥散性特征,所提算法仅8个像素点的主轴方向偏转角大于5°,且这8个像素点均不在图像的感兴趣区域。此外,该算法所得图像的各项异性（FA）以及平均弥散率（MD）都接近为0,完全满足临床诊断的要求;且面对裁剪强度小于0.7,旋转角度小于15°等常见的噪声攻击,该算法的水印正确率达到95%以上,能有效保护弥散...     

基于DWT域的混沌置乱二值图像数字水印新算法

提出了一种基于DWT(Discrete Wavelet Transform)域有意义二值图像数字水印新算法．利用广义猫映射产生的混沌序列对水印序列的嵌入位置进行置乱，增加了嵌入水印的安全性；并利用改正的二值运算方法将水印嵌入到图像深层小波域的低频子图中．水印的检测不需要原始图像．大量仿真结果证明了该算法嵌入的数字水印既具有很好的隐蔽性，又具有很理想的鲁棒性．     

面向屏幕拍摄的端到端鲁棒图像水印算法

目的 在抗屏摄鲁棒图像水印算法的研究中,如何在保证含水印图像视觉质量的同时提高算法的鲁棒性是存在的主要挑战。为此,提出一种基于深度学习的端到端网络框架以用于鲁棒水印的嵌入与提取。方法 在该网络框架中,本文设计了包含摩尔纹在内的噪声层用以模拟真实屏摄噪声造成的失真,并通过网络训练来学习到抵抗屏摄噪声的能力,增强网络生成的含水印图像的鲁棒性;同时引入了最小可察觉失真（just noticeable distortion,JND）损失函数,旨在通过监督图像的JND系数图与含有水印信息的残差图之间的感知差异来自适应控制鲁棒水印的嵌入强度,以提高生成的含水印图像的视觉质量。此外,还提出了两种图像区域自动定位方法,分别用于解决：拍摄图像中前景与背景分割即含水印图像区域的定位矫正问题,以及含水印图像经过数字裁剪攻击后的解码问题。结果 实验结果表明,引入JND损失函数后嵌入水印图像的视觉质量得到了提高,平均的峰值信噪比（peak signalto-noise ratio,PSNR）、结构相似性（structural similarity,SSIM）可分别达到30.937 1 dB和0.942 4。加入摩尔纹的噪声模拟层后,所提算法的误码率可下降1%～3%,具有抵抗屏摄噪声的能力。另外,将图像的R通道嵌入用于抗裁剪的模板,使得算法可有效抵抗较大程度的数字裁剪攻击。本文算法的计算复杂度较低,对单幅图像进行嵌入时,定位与提取操作的总耗时小于0.1 s,可满足实际应用场景的实时性需求。结论 本文算法的嵌入容量和生成的含水印图像视觉质量较为理想,且在不同拍摄距离、角度以及不同拍摄和显示设备条件下的鲁棒性优于已报道的主流算法。     

Chaotic based secure watermarking approach for medical images

In this paper, a chaotic based secure medical image watermarking approach is proposed. The method is using non sub-sampled contourlet transform (NSCT), redundant discrete wavelet transform (RDWT) and singular value decomposition (SVD) to provide significant improvement in imperceptibility and robustness. Further, security of the approach is ensured by applying 2-D logistic map based chaotic encryption on watermarked medical image. In our approach, the cover image is initially divided into sub-images and NSCT is applied on the sub-image having maximum entropy. Subsequently, RDWT is applied to NSCT image and the singular vector of the RDWT coefficient is calculated. Similar procedure is followed for both watermark images. The singular value of both watermarks is embedded into the singular matrix of the cover. Experimental evaluation shows when the approach is subjected to attacks, using combination of NSCT, RDWT, SVD and chaotic encryption it makes the approach robust, imperceptible, secure and suitable for medical applications.

     

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.     

Weighted matrix based reversible watermarking scheme using color image

High capacity, secure, reversible watermarking scheme using a color image for image authentication and tampered detection is still an important area of research. In this investigation, we have proposed a weighted matrix based reversible watermarking scheme using the color image which provides image authentication and tampered detection. Here, we decomposed the original image into R, G, B color components and partitioned into (3 × 3) pixel blocks then we performed the sum of entry-wise-multiplication operations using a modified weighted matrix to embed the watermark. The watermark embedding locations are stored within an index file to enhance security, increase data hiding capacity, gain good visual quality, achieve reversibility and confirm authenticity. The proposed watermarking scheme not only perform authentication and tampered detection but also improved both data embedding capacity up to 8.00 (bpp) as well as increase visual quality measured by PSNR, 50.03 (dB). Finally, the scheme is compared with other existing state-of-the-art methods and gives a reasonably better performance in terms of visual quality and hiding capacity. Our scheme has been evaluated through various steganographic analysis and observed that the scheme is secure and robust against various attacks.     

基于子块分割的自适应式全盲图像水印算法

为了提高水印的鲁棒性,文中提出了一种基于子块分割的自适应全盲水印算法ABWASS。在嵌入水印时,该算法根据宿主特征矩阵嵌入自适应调整后的水印图像,并使用改进的两阶段DWT方法在LH2子带中融入水印图像的关键信息,从而得到含双重水印的图像;提取水印时,首先分离水印分块方式等关键信息,并通过DCT变换获得特征矩阵,进而提取水印图像。由于该方法在获得含有水印的图像时,根据宿主图像对水印进行了微调,并嵌入了原始水印尺寸,因此在提取过程可以实现全盲。实验结果表明,较已有方法,所提算法能够很好地抵抗多数常规攻击和几何攻击,并且在抵抗混合攻击上其性能均得到了提高,最大提升了2.7%;同时,其还具备较好的水印隐蔽性和实用性。     

A self-adaptive image normalization and quaternion PCA based color image watermarking algorithm

This paper proposes a novel robust digital color image watermarking algorithm which combines color image feature point extraction, shape image normalization and QPCA (quaternion principal component algorithm) based watermarking embedding (QWEMS) and extraction (QWEXS) schemes. The feature point extraction method called Mexican Hat wavelet scale interaction is used to select the points which can survive various attacks and also be used as reference points for both watermarking embedding and extraction. The normalization shape image of the local quadrangle image of which the four corners are feature points of the original image is invariant to translation, rotation, scaling and skew, by which we can obtain the relationship between the feature images of the original image and the watermarked image which has suffered with geometrical attacks. The proposed QWEMS and QWEXS schemes which denote the color pixel as a pure quaternion and the feature image as a quaternion matrix can improve the robustness and the imperceptibility of the embedding watermarking. To simplify the eigen-decomposition procedure of the quaternion matrix, we develop a calculation approach with which the eigen-values and the corresponding eigen-vectors of the quaternion matrix can be computed. A binary watermark image is embedded in the principal component coefficients of the feature image. Simulation results demonstrate that the proposed algorithm can survive a variety of geometry attacks, i.e. translation, rotation, scaling and skew, and can also resist the attacks of many signal processing procedures, for example, moderate JPEG compression, salt and pepper noise, Gaussian filtering, median filtering, and so on.