一种基于DCT域的灰度级盲水印嵌入优化算法

从改进的角度,提出一种基于宿主图像的DCT域嵌入较大分辨率灰度级数字盲水印的优化算法。该算法采用视觉频率、图像灰度增强和灰度图像门限值JND量化选取DCT子块系数,对嵌入宿主图像的较大分辨率256级灰度水印先行压缩和自同构置乱,再行嵌入宿主图像。该算法在水印提取时无需宿主图像和原始水印的参与,较大幅度地提高了水印的嵌入量。实验结果表明此算法抵抗压缩的能力强,视觉图像无明显降质,具有较强的鲁棒性和顽健性。     

A blind watermarking method using maximum wavelet coefficient quantization

This paper proposes a blind watermarking algorithm based on maximum wavelet coefficient quantization for copyright protection. The wavelet coefficients are grouped into different block size and blocks are randomly selected from different subbands. We add different energies to the maximum wavelet coefficient under the constraint that the maximum wavelet coefficient is always maximum in a block. The watermark is embedded the local maximum coefficient which can effectively resist attacks. Also, using the block-based watermarking, we can extract the watermark without using the original image or watermark. Experimental results show that the proposed method is quite robust under either non-geometry or geometry attacks.     

一种DCT域自适应音频水印算法*

数字水印技术中水印强度是影响水印鲁棒性的重要参数。当前大多数的水印算法均利用实验来确定水印强度,但实验具有很大的随机性,得到合适的水印强度需要大量的实验。提出了一种DCT(discrete cosine transform)域基于信噪比(signal noise ratio,SNR)水印强度自适应的音频水印。首先将载体音频分帧,然后根据对嵌入水印后音频品质要求的SNR计算各帧的水印强度,选择可嵌入强度大的帧,将一个水印比特信息嵌入一帧的DCT的直流系数,水印强度将自适应于各帧。实验结果证明了该算法具有较好     

Robust and efficient content-based digital audio watermarking

This paper proposes a set of digital watermarking schemes for WAV audio, WAV-table synthesis audio and compressed audio. The watermark embedding scheme is closely related to audio content and based on the human auditory system. The experimental results in listening and robustness illustrate that the proposed watermarking schemes can achieve an optimal balance between audibility and robustness of the watermarked audio. The proposed methods are also very useful and effective for copyright protection, tracing illegal distribution and other applications.     

DCT域加密自适应数字水印算法*

针对常规的DCT域数字水印算法自适应性差的缺陷,提出一种基于DCT(离散余弦变换)域加密和自适应相结合的数字水印算法。该算法在水印嵌入前先对水印进行Arnold变换,这样做一方面降低了水印数据间的相关性,另一方面也对水印数据进行了加密处理从而大大提高了水印的安全性。通过JPEG量化矩阵选取一定数量的DCT系数用于嵌入水印。嵌入过程中对水印的嵌入强度进行动态自适应调节,在确保了隐蔽性的前提下使得提取效果更好。实验表明,该算法对均值滤波、高斯噪声、椒盐噪声,以及JPEG压缩等攻击有一定的鲁棒性。     

基于系数关系的DCT域数字图像水印

提出了一种DCT域的数字图像盲水印算法,该算法将图像进行8*8分块后对各块图像进行DCT变换。之后将水印信息嵌入到选取的中频系数之间的关系中;提取水印时不需要原始图像,实现了盲检测;而且水印嵌入位置可由密码控制,增强了算法的保密性和灵活性;不可感知性和鲁棒性可调。仿真实验结果表明该算法在保证水印不可感知性的情况下,对一些常见的恶意攻击具有良好的鲁棒性。     

基于小波变换的三维网格数字水印技术研究

大部分三维数字水印算法更多地关注水印的鲁棒性而忽视了三维模型的视觉效果。为了解决这一问题,提出了一种基于小波变换的三维网格数字水印新算法,该算法以典型的三角网格模型作为水印载体。提取三维模型中的显著区域,并将三维模型进行旋转归一化处理,以此保证对三维模型平移、缩放或旋转攻击都有很强的鲁棒性;将三维模型转化到球面坐标下并进行小波变换,在低频和高频系数下嵌入水印;经过小波逆变换得到嵌入水印后的三维模型,实验结果表明提出的算法既对多类攻击方式具有鲁棒性,又保持了三维模型的视觉效果。     

图像数字水印的攻击及基准测试软件

随着各种图像数字水印算法的提出，对所有数字水印方案引入一个合理、统一的基准测试软件将对数字水印的发展起到很好的促进作用。文章在描述影响图像数字水印系统性能参数的基础上，对数字水印的各种典型的攻击方式作了较完整的分析，最后对现有的基准测试程序Stirmark进行了探讨，指出了其需改进之处。     

Frame-synchronized blind speech watermarking via improved adaptive mean modulation and perceptual-based additive modulation in DWT domain

This paper presents a blind speech watermarking algorithm that adopts different strategies to embed synchronization codes and information bits into separate DWT subbands. Speech frames for data hiding are chosen based on intensity thresholding. Under the guidance of the source-filter theory, a bipolar synchronization code sequence is substituted for the noisy part of the inverse filtered excitation in the 2nd level detail subband. Such a design allows the increase of embedding strength without adversely disturbing the pitch harmonics of voiced speech. Experiment results show that a synchronization code of size 640 is sufficient to render reliable detection. The PESQ metrics indicate that the quality degradation due to the synchronization code embedding is almost negligible. As for the binary embedding in the 2nd level approximation subband, we improve the adaptive mean modulation scheme to secure the retrieval of watermark bits on a frame basis. Experiment results confirm that, with the payload capacity set at 200 bit per second (bps), the proposed scheme demonstrates better robustness than three other DWT-based methods in the presence of commonly encountered signal processing attacks. Furthermore, reducing the capacity down to 100 bps alters the low-frequency spectral distribution, which contributes noteworthy improvements in robustness and imperceptibility.     

DWT-SVD域全盲自嵌入鲁棒量化水印算法

引入自嵌入技术提出一种DWT-SVD域全盲鲁棒量化水印算法,只需借助攻击图像进行版权认证。对原始图像先进行DWT,将小波低频子带分成互不重叠的子块,对每个子块进行SVD,通过对比相邻两个子块最大奇异值的大小关系产生特征水印序列,然后将选定的自嵌入特征水印序列通过奇偶量化规则自嵌入原始图像小波低频子带每个子块的最大奇异值,最后进行SVD合成和IDWT产生含水印图像。算法具有良好的不可见性和安全性,并且通过结合自嵌入特征水印序列和盲提取认证水印序列达到全盲检测。实验结果表明,算法具有较强的抵抗添加高斯噪声、添加椒盐噪声、高斯低通滤波、中值滤波、剪切、JPEG压缩和混合攻击的鲁棒性。     

A novel image watermarking in redistributed invariant wavelet domain

Most existing digital watermarking algorithms, which are based on the Discrete Wavelet Transform, are not robust to geometric distortions, even if for some special distortions, such as multiples of 90° rotation of integers and image flipping, which change the location of pixels but have no effect on the value of the image. Therefore, to solve the problem, according to Haar wavelet transform theory, the redistributed invariant wavelet domain is constructed and proofed in this paper; a novel image watermarking algorithm, based on the invariant domain, is proposed to eliminate such distortions. The experimental results showed that the proposed algorithm not only can resist the common image processing operations, but also successfully resist the distortions that result from multiples of 90° rotations of integers and image flipping.     

HSV色彩空间盲嵌盲检盲提取DCT域视频水印

提出了一种基于欧拉数及HSV色彩空间的视频水印离散余弦变换(DCT)算法。在视频中选择欧拉数较小的帧,在HSV色彩空间亮度分量DCT中频系数中嵌入水印。该算法能实现盲嵌入、盲检测和盲提取,且健壮性强、透明性好,能经受噪声、滤波、剪切、压缩、帧插入及删除等图像、视频处理与攻击。     

DCT域音频水印透明健壮算法

提出一种新的基于离散余弦变换的数字音频水印算法。把音频信号划分为包含相同采样点的若干帧,每帧划分为若干节。对指定帧的第一节、第二两节实施DCT变换,将二者DCT中、高频系数的绝对值之和进行比较,结合水印序列为“0”或“1”,采取不改变、缩小及增加中、高频DCT系数的方法,在DCT系数中嵌入水印。实验证明,该算法具有较强的健壮性,较好的透明性,提取水印属盲水印提取,能经受重采样、重新量化、添加噪声、低通滤波、音频格式转换等常见信号处理及攻击。     

Robust watermarking of databases in order-preserving encrypted domain

Security of databases has always been a hot topic in the field of information security. Privacy protection can be realized by encrypting data, while data copyright can be protected by using digital watermarking technology. By combining these two technologies, a database’s copyright and privacy problems in the cloud can be effectively solved. Based on order-preserving encryption scheme (OPES), circular histogram and digital watermarking technology, this paper proposes a new robust watermarking scheme for protection of databases in the encrypted domain. Firstly, the OPES is used to encrypt data to avoid exposing the data in the cloud. Then, the encrypted data are grouped and modified by the use of a circular histogram for embedding a digital watermark. The common data query operations in database are available for the encrypted watermarking database. In receivers, the digital watermark and the original data can be restored through a secret key and a key table. Experimental results have shown that the proposed algorithm is robust against common database attacks in the encrypted domain.     

基于HVS和关系的DCT域彩色图像水印方案

提出了一种基于人类视觉系统和关系的离散余弦变换域水印技术。首先对二值水印图像进行混沌加密和Arnold置乱处理;其次对载体彩色图像的每一分量进行8×8分块的离散余弦变换;最后根据每一分块的亮度和纹理掩蔽特性和水印图像的像素取值来自适应调整选定位置的离散余弦变换系数的大小关系以嵌入水印。实验表明,提出的算法具有较好的透明性和抵抗攻击的能力,且在红色分量嵌入的水印比在蓝色或绿色分量嵌入的水印对滤波、有损压缩攻击等具有更好的鲁棒性。与同类算法相比,提出的算法具有更好的性能。     

图像归一化与伪Zernike矩的鲁棒水印算法研究*

以基于矩的图像归一化技术及伪Zernike矩相关知识为基础,提出一种可有效抵抗几何攻击的数字水印新算法。算法首先利用归一化技术将原始图像映射到几何不变空间内;然后结合不变质心理论提取出归一化图像的重要区域;最后通过量化调制伪Zernike矩幅值将水印嵌入到重要区域中。仿真实验表明,该算法不仅具有较好的透明性,而且对常规信号处理(滤波、锐化、加噪和JPEG压缩等)和几何攻击(全局仿射变换、局部失真等)均具有较好的鲁棒性。     

DCT域基于PSNR的扩频水印算法

数字水印技术是信息隐藏和版权维护的一种有效方法。在先前的研究基础上提出了DCT域中如何根据水印图像与原始图像间的PSNR来估计水印的多重水印嵌入强度,并由此提出一个基于PSNR的扩频水印强度的估计公式。实验结果表明,提出的嵌入强度估计公式误差小,具有一定的准确性,算法具有一定的鲁棒性。     

A robust watermarking algorithm based on QR factorization and DCT using quantization index modulation technique

We propose a robust digital watermarking algorithm for copyright protection.A stable feature is obtained by utilizing QR factorization and discrete cosine transform(DCT) techniques,and a meaningful watermark image is embedded into an image by modifying the stable feature with a quantization index modulation(QIM) method.The combination of QR factorization,DCT,and QIM techniques guarantees the robustness of the algorithm.Furthermore,an embedding location selection method is exploited to select blocks with small modifications as the embedding locations.This can minimize the embedding distortion and greatly improve the imperceptibility of our scheme.Several standard images were tested and the experimental results were compared with those of other published schemes.The results demonstrate that our proposed scheme can achieve not only better imperceptibility,but also stronger robustness against common signal processing operations and lossy compressions,such as filtering,noise addition,scaling,sharpening,rotation,cropping,and JPEG/JPEG2000 compression.     

Robust and imperceptible image watermarking technique based on SVD,DCT, BEMD and PSO in wavelet domain

This article introduces a robust image watermarking primarily founded on DWT (discrete wavelet transform), BEMD (bi-dimensional empirical mode decomposition), DCT (discrete cosine transform), PSO (particle swarm optimization), and SVD (singular value decomposition). During the process of embedding, 2nd level DWT is used to decompose the cover image into sub-bands. DWT is also used for the decomposition of images for watermarking. Further, BEMD decomposition runs to implement on the selected band of DWT. For optimization, PSO is used for complex and multidimensional searches. Further DCT as well as SVD applied to the selected band. The embedding and scaling factors are embedded with the help of a security key. Further, this method is followed by using the inverse of ISVD, IDCT, IDWT, and IBEMD. The Watermark image is extracted by the extraction process. Experimental results show that the suggested technique is robust compared to several geometrical and non-geometrical attacks. Therefore, this proposed technique provides better visible quality and robustness against numerous attacks like salt and pepper, Gaussian filter, rotation, median filter, speckle, gamma correction, scaling, and shearing for gray scale images and provides the watermarked image with good quality.