DCT域图像水印:嵌入对策和算法

 DCT域的隐形水印应嵌入哪里,水印才足够稳健?尽管许多关于DCT域水印算法的文献赞成水印应放在对视觉效果重要的分量,但DC分量总是被无一例外地排除在外.本文提出了一个DCT域隐形水印的嵌入对策和一个应用该对策的自适应水印算法.基于对图像DCT系数振幅的定量分析,我们指出:DC分量比任何AC分量有更大的感觉容量,从稳健性的角度,DC分量最适合用来嵌入水印.应用这个对策,本文提出了一个把视觉系统纹理掩蔽特性结合到水印编码过程的自适应水印算法.实验结果有效地支持了这个结论,所产生的隐形水印体现了很好的稳健性.     

Watermarking on Colored Images

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Towards robust image watermarking: combining content-dependent key,moment normalization,and side-informed embedding

In digital watermarking, robustness is still a challenging problem if different sets of attacks need to be tolerated simultaneously. In this paper, we deal with this problem by using an integrated solution involving side-informed embedding, moment normalization, and content-dependent watermarks. First, a new image watermarking method based on the concept of communications with side information is proposed. We investigate the characteristics of mean filtering in formulating new watermark embedding and extraction processes. Second, regarding resistance to geometrical attacks, we do not rely on the concept of pilot signals because they are vulnerable to synchronization removal attacks. We instead use block-based watermarking and moment normalization mechanisms to recover geometrical distortions. Third, regarding resistance to the copy attack, the content-dependent watermark is employed to avoid treating an un-watermarked image as one that has been watermarked. The robustness of our approach has been verified using both the StirMark and the copy attack.     

DCT域中DC分量上嵌入水印的算法

在DCT域中,存在AC,DC两个分量,通常在图像加密过程中,将水印嵌入AC分量,特别是中频系数上。本文从鲁棒性角度出发,通过实验证明,在实际应用中,DC分量比AC分量更适合嵌入水印。DC分量嵌入水印是有效的,且具有很好的鲁棒性,能抵御加在已嵌入水印的图像上的剪切、有损压缩的攻击。     

Oriented modulation for watermarking in direct binary search halftone images

In this paper, a halftoning-based watermarking method is presented. This method enables high pixel-depth watermark embedding, while maintaining high image quality. This technique is capable of embedding watermarks with pixel depths up to 3 bits without causing prominent degradation to the image quality. To achieve high image quality, the parallel oriented high-efficient direct binary search (DBS) halftoning is selected to be integrated with the proposed orientation modulation (OM) method. The OM method utilizes different halftone texture orientations to carry different watermark data. In the decoder, the least-mean-square-trained filters are applied for feature extraction from watermarked images in the frequency domain, and the na?ve Bayes classifier is used to analyze the extracted features and ultimately to decode the watermark data. Experimental results show that the DBS-based OM encoding method maintains a high degree of image quality and realizes the processing efficiency and robustness to be adapted in printing applications.     

Hidden digital watermarks in images

An image authentication technique by embedding digital "watermarks" into images is proposed. Watermarking is a technique for labeling digital pictures by hiding secret information into the images. Sophisticated watermark embedding is a potential method to discourage unauthorized copying or attest the origin of the images. In our approach, we embed the watermarks with visually recognizable patterns into the images by selectively modifying the middle-frequency parts of the image. Several variations of the proposed method are addressed. The experimental results show that the proposed technique successfully survives image processing operations, image cropping, and the Joint Photographic Experts Group (JPEG) lossy compression.     

Robust template matching for affine resistant image watermarks

Digital watermarks have been proposed as a method for discouraging illicit copying and distribution of copyrighted material. This paper describes a method for the secure and robust copyright protection of digital images. We present an approach for embedding a digital watermark into an image using the Fourier transform. To this watermark is added a template in the Fourier transform domain to render the method robust against general linear transformations. We detail a new algorithm based on polar maps for the accurate and efficient recovery of the template in an image which has undergone a general affine transformation. We also present results which demonstrate the robustness of the method against some common image processing operations such as compression, rotation, scaling, and aspect ratio changes.     

复合的海图安全防护技术研究

提出了一种二维电子海图自适应水印技术,利用平移不变策略,获得海图空间内频域较稳定的一个水印嵌入载体集合。为了防止水印嵌入幅度过大而影响海图使用和从水印算法的安全性考虑,提出了灰度平衡控制方案,计算每个划分好的矩形区域内可嵌入水印的最大容量。实验表明,该方法能够适应海图常规操作所带来的数据扰动,具有较好的顽健性。     

Multiscale fragile watermarking based on the Gaussian mixture model.

In this paper, a new multiscale fragile watermarking scheme based on the Gaussian mixture model (GMM) is presented. First, a GMM is developed to describe the statistical characteristics of images in the wavelet domain and an expectation-maximization algorithm is employed to identify GMM model parameters. With wavelet multiscale subspaces being divided into watermarking blocks, the GMM model parameters of different watermarking blocks are adjusted to form certain relationships, which are employed for the presented new fragile watermarking scheme for authentication. An optimal watermark embedding method is developed to achieve minimum watermarking distortion. A secret embedding key is designed to securely embed the fragile watermarks so that the new method is robust to counterfeiting, even when the malicious attackers are fully aware of the watermark embedding algorithm. It is shown that the presented new method can securely embed a message bit stream, such as personal signatures or copyright logos, into a host image as fragile watermarks. Compared with conventional fragile watermark techniques, this new statistical model based method modifies only a small amount of image data such that the distortion on the host image is imperceptible. Meanwhile, with the embedded message bits spreading over the entire image area through the statistical model, the new method can detect and localize image tampering. Besides, the new multiscale implementation of fragile watermarks based on the presented method can help distinguish some normal image operations such as JPEG compression from malicious image attacks and, thus, can be used for semi-fragile watermarking.     

DCT域音频水印:嵌入对策和算法

为保证DCT域水印的鲁棒性,研究水印信号的嵌入位置非常必要.对音频载体,尽管有许多文献提出将水印嵌在中频系数或对听觉效果重要的系数上,但始终缺乏一个统一的方法.本文在DCT噪声信号模型研究的基础上,提出了一种新的音频水印嵌入位置选择策略和一个应用该策略的自适应音频水印算法.通过定义DCT系数的噪声敏感度,建立了水印嵌入位置和嵌入水印后的音频信号的听觉感知性之间的关系,根据音频水印的不可听性的要求选择最优的嵌入位置,然后调节水印强度来满足鲁棒性的要求,从而最大程度地保持音频水印的不可听性和鲁棒性,为解决音频水印嵌入过程中不可听性和鲁棒性之间的矛盾提供了一种策略.应用该策略,本文提出了一个自适应音频水印算法.实验证实了算法的鲁棒性.     

Content protection in grayscale and color images based on robust digital watermarking

The concept of digital rights management architecture for multimedia will be presented in this paper, with focus on robust digital image watermarking, which is able to undergo geometrical attacks performed against the embedded watermarks. Geometrical attacks are still an open problem for many digital watermarking algorithms used in present time. Most of geometrical attacks can be described by using affine transforms. A new approach to improve robustness against geometrical attacks is presented. The discrete Fourier transform and log-polar mapping are used for watermark embedding and for watermark detection. Some attacks against the embedded watermarks are performed and the results are given. Also two modifications, usage of the proposed method as a synchronization template and implementation for the color images, are presented and experimental results are given too.     

一种双帧数字图像的双盲水印技术

本文提出一种新的安全水印嵌入技术:同时对两帧数字图像嵌入两种不同水印,对任意提取一幅图像的水印,无法恢复两个水印的任何信息.在获得双密钥情况下,方可恢复两幅图像的水印.从数学上证明了我们提出的新技术的有效性,并对算法安全性给予了分析.在变换域上给出了实现了双盲水印的算法,采用StirMark水印测试软件进行了一系列攻击性试验,其测试结果表明此技术提供了一种新的数字版权保护的方法.     

一种基于HVS和DC分量的DCT域数字水印算法

为增强数字水印的透明性和鲁棒性,提出了一种基于人类视觉系统和直流分量的DCT变换域数字水印算法。算法依据原始图像的纹理掩蔽特性确定水印信息的嵌入位置,依据照度掩蔽特性确定水印信息的嵌入强度,将二值水印图像嵌入到原始图像在DCT域的直流分量中。在仿真实验中与同等条件下的中频嵌入做比较,实验结果表明,该算法提取的水印具有良好的透明性和鲁棒性。     

基于ICA的智能数字水印技术

该文提出了一种基于智能信息分析方法--独立分量分析的智能数字水印新算法。水印嵌入之前先对其进行预处理,嵌入过程可以在图像任意作用域中实现,并给出了小波域中的一种闭环嵌入方法。水印嵌入的强度由小波域视觉模型决定。在不需要任何原始图像、水印和攻击类型等信息的情况下,该算法不仅可以检测到水印而且可以完全提取水印,实现了真正意义上的水印盲检测,并对多个水印嵌入的情况也可以进行水印提取。水印检测的精确程度取决于图像与水印之间的独立性以及所采用的密钥。实验过程中攻击由通用水印测试软件Stirmark产生,实验数据证明本文提出的水印算法对Stirmark提供的各种攻击剪切、滤波、图象压缩、删行、删列、几何攻击以及多种攻击同时存在时都具有很好的鲁棒性。     

Digital watermarking algorithm in SWT domain based on robust local feature

Aiming at the challenging work to design a robust digital audio watermarking algorithm against desynchronization attacks,a new second generation digital audio watermarking in stationary wavelet transform (SWT) domain based on robust local audio feature was proposed.First,the first-order smooth gradient response of the low-pass sub-band coefficient was calculated using Gaussian filter.Then,the short-term energy was utilized to adaptively determine local feature audio segments for embedding.Finally,the watermark information was embedded into local feature audio segments with spread transform dither modulation.The experimental results show that the proposed approach has not only good transparency,but also has strong robustness against common audio processing such as MP3 compression and good robustness against the desynchronization attacks such as pitch-scale modification et al.A SWT domain audio feature point extraction method based on smooth gradient is proposed,which effectively solves the drawbacks of poor stability and uneven distribution of audio feature points,and improves the resistance of digital audio watermarks to amplitude-scale modification,pitch-scale modification,random cropping,and jittering attacks.     

一种小波域自适应鲁棒闭环数字盲水印技术

本文提出了一种基于小波域的闭环自适应图像鲁棒数字盲水印技术.水印的嵌入过程是一个闭环过程,且其嵌入的位置及强度均与原始图像有关.水印嵌入的初始强度由小波域图像压缩的量化因子决定,并根据检测要求不断的进行调整,从而达到水印的最佳嵌入.本文证明了这种闭环系统的收敛性,并且给出了水印检测过程中正确检测概率和虚警检测概率的求解公式,可用于闭环系统的检测性能判决条件.水印的检测过程中不需要任何原始图像和原始水印信号的信息,采用独立分量分析实现对水印信号的盲检测.检测过程中不仅可以检测到水印的存在,而且可以提取出嵌入到图像中的多个水印信号.实验结果证实了本文提出的闭环自适应数字盲水印技术优于传统的自适应水印技术,水印检测过程中在不需要考虑水印图像所经历的攻击类型及攻击参数的情况下可以正确的提取水印信号.本文提出的水印算法对通用水印测试软件Stirmark具有很好的鲁棒性.     

A feature-based robust digital image watermarking scheme

A robust digital image watermarking scheme that combines image feature extraction and image normalization is proposed. The goal is to resist both geometric distortion and signal processing attacks. We adopt a feature extraction method called Mexican hat wavelet scale interaction. The extracted feature points can survive a variety of attacks and be used as reference points for both watermark embedding and detection. The normalized image of an image (object) is nearly invariant with respect to rotations. As a result, the watermark detection task can be much simplified when it is applied to the normalized image. However, because image normalization is sensitive to image local variation, we apply image normalization to nonoverlapped image disks separately. The disks are centered at the extracted feature points. Several copies of a 16-bit watermark sequence are embedded in the original image to improve the robustness of watermarks. Simulation results show that our scheme can survive low-quality JPEG compression, color reduction, sharpening, Gaussian filtering, median filtering, row or column removal, shearing, rotation, local warping, cropping, and linear geometric transformations.     

Applying informed coding and embedding to design a robust high-capacity watermark

We describe a new watermarking system based on the principles of informed coding and informed embedding. This system is capable of embedding 1380 bits of information in images with dimensions 240 x 368 pixels. Experiments on 2000 images indicate the watermarks are robust to significant valumetric distortions, including additive noise, low-pass filtering, changes in contrast, and lossy compression. Our system encodes watermark messages with a modified trellis code in which a given message may be represented by a variety of different signals, with the embedded signal selected according to the cover image. The signal is embedded by an iterative method that seeks to ensure the message will not be confused with other messages, even after addition of noise. Fidelity is improved by the incorporation of perceptual shaping into the embedding process. We show that each of these three components improves performance substantially.     

A Video Watermarking DRM Metho d Based on H.264 Compressed Domain with Low Bit-Rate Increasement

It gets more and more important for video copyright protection, it is necessary to provide e?cient H.264 compression domain watermarking for video Digital rights management(DRM). A new watermarking method based on H.264 compressed domain is proposed for video DRM, in which the embedding and extracting procedure are performed using the syntactic elements of the com-pressed bit stream. In this way, complete decoding is un-necessary in both embedding and extracting processes. Based on the analysis of the time and space, some appro-priate sub-blocks are selected for embedding watermarks, increasing watermark robustness while reducing the dec-lination of the visual quality. In order to avoid bit-rate increasing and strengthen the security of the proposed video watermarking scheme, only a set of nonzero coe?-cients quantized in different parts of macroblocks is chosen for inserting watermark. The experiment results show the proposed scheme can achieve excellent robustness against some common attacks, the proposed scheme is secure and e?cient for video content DRM protection.     

基于盲源分离的小波域多重音频水印方法

该文利用盲源分离理论,提出一种小波域的多重音频水印方法。为了解决多水印嵌入过程中经常需要考虑的嵌入顺序问题,同时增强水印方法的安全性,本文将两路水印信号与一路等长的混沌序列进行混合,得到嵌入水印信号。然后,利用线性混合方法,将嵌入水印信号与选定的小波系数进行混合,得到隐秘信号。水印提取时,利用独立分量分析算法,提取嵌入水印信号,再经过后处理过程,得到原始水印。该水印方案是一种盲水印方法,可以将多个作者信息同时嵌入到音频作品中,而不需要考虑水印的嵌入顺序。实验结果表明,该方法对常规的信号处理操作具有良好的鲁棒性,以及良好的抵抗时间轴同步攻击的能力。