基于矩阵Schur分解的彩色图像盲水印算法

针对目前大多数彩色图像数字水印算法中嵌入的水印是二值灰度图像且为提取水印时需要原始宿主图像或原始水印的现状,本文提出了一种将彩色水印嵌入到彩色宿主图像中的盲水印算法。该算法分析了矩阵Schur分解的基本特征,通过修改其上三角矩阵对角线上的最大能量元素来嵌入水印,水印提取过程达到盲提取的目的。实验结果表明,该水印方案不但嵌入和提取的速度快,而且具有较好的水印不可见性(峰值信噪比达到40dB以上)和较强的鲁棒性。     

A multimedia application for watermarking digital images based on a content based image retrieval technique

The current work is focused on the implementation of a robust multimedia application for watermarking digital images, which is based on an innovative spread spectrum analysis algorithm for watermark embedding and on a content-based image retrieval technique for watermark detection. The existing highly robust watermark algorithms are applying “detectable watermarks” for which a detection mechanism checks if the watermark exists or not (a Boolean decision) based on a watermarking key. The problem is that the detection of a watermark in a digital image library containing thousands of images means that the watermark detection algorithm is necessary to apply all the keys to the digital images. This application is non-efficient for very large image databases. On the other hand “readable” watermarks may prove weaker but easier to detect as only the detection mechanism is required. The proposed watermarking algorithm combine’s the advantages of both “detectable” and “readable” watermarks. The result is a fast and robust multimedia application which has the ability to cast readable multibit watermarks into digital images. The watermarking application is capable of hiding 2¹⁴ different keys into digital images and casting multiple zero-bit watermarks onto the same coefficient area while maintaining a sufficient level of robustness.     

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.     

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.     

Perceptual Digital Watermarking for Image Authentication in Electronic Commerce

Digital watermarking has been presented to protect the copyright of electronic multimedia data. The previous proposed watermarking algorithms mostly embed sequences of random numbers or binary images as the watermarks. In this paper, an image accreditation technique by embedding digital gray-level image watermarks in images is proposed. In the proposed method, the host image and the watermark are decomposed into wavelet coefficients. The contextual energies of the host-image wavelet coefficients are computed to select embedding coefficients. The watermark wavelet coefficients are sorted and then embedded in the selected host coefficients. The experiments show that the proposed method provides extra robustness against JPEG-compression, image-processing, and even composite attacks compared to the traditional embedding methods. Moreover, the proposed method has no need of the original image to extract the embedded watermarks. The proposed method facilitates electronic commerce application developers to select adequate digital watermarking techniques for their development systems.     

Visible watermarking based on importance and just noticeable distortion of image regions

Visible watermarking is the process of embedding data (watermark) into a multimedia object (video/image) such that the embedded watermark is perceptible to a human observer. Many times, visible watermarks occlude important portion of multimedia objects. This paper introduces a visible watermarking algorithm to embed a binary logo watermark at N non-overlapping positions in an image such that important portions of the image are not occluded. The important portions are found through visual saliency computation or available human eye fixation density maps. In the proposed visible watermarking, just noticeable distortion is used to adaptively filter the watermark embedding energy based on the image content. A mathematical model in terms of information-content-weighted-structural-similarity-index and visual importance is proposed to find optimal watermark embedding strength. We tested the algorithm on several color images of different sizes and on several binary watermarks of different sizes and found the results to be very promising as per the requirements in visible watermarking. When compared to the state-of-the-art, we also found that the proposed technique does better in not hiding the details of any test image.     

基于DCT变换的图象分块数字水印算法

数字水印是数字作品版权保护的重要技术手段,不可察觉性和鲁棒性是图象水印中基本要求,但它们却是一对互相制约的因素.该算法提出了一种新的数字水印嵌入和提取方法,以一幅图象作为水印,信息量大,优于通常把文本,字符作为水印的方法;分块随机嵌入提高了水印嵌入的顽健性;根据图象局部特征确定水印的嵌入强度,使水印的嵌入强度随图象局部特征变化而变化.针对典型攻击的实验结果表明该算法具有很好的鲁棒性.     

Wavelet-based image watermarking with visibility range estimation based on HVS and neural networks

This work proposes a wavelet-based image watermarking (WIW) technique, based on the human visible system (HVS) model and neural networks, for image copyright protection. A characteristic of the HVS, which is called the just noticeable difference (JND) profile, is employed in the watermark embedding to enhance the imperceptibility of the technique. First, we derive the allowable visibility ranges of the JND thresholds for all coefficients of a wavelet-transformed image. The WIW technique exploits the ranges to compute the adaptive strengths to be superimposed in the wavelet coefficients while embedding watermarks. An artificial neural network (ANN) is then used to memorize the relationships between the original wavelet coefficients and its watermark version. Consequently, the trained ANN is utilized for estimating the watermark without the original image. Many existing schemes require the original image to be involved in the calculation of the JND profile of the image. Finally, computer simulations demonstrate that both transparency and robustness of the WIW technique are superior to that of other proposed methods.     

Secure variable-capacity self-recovery watermarking scheme

Since existing watermarking schemes usually cannot recover the tampered position, a secure variable-capacity self-recovery watermarking scheme is proposed. Both watermark embedding capacity and security are taken into account. The original image is divided into texture blocks and smooth blocks, and the texture blocks not only save traditional information, and save the “details” information. The so-called “details” information refers to the texture information, which not only can effectively resist mean attack, but also help to improve the quality of the recovered image to meet the needs of practical work. And then according to the characteristics of different blocks, the different length compound watermarks are produced. The so-called “compound watermarks” include the authentication watermarks and information watermarks. Authentication watermarks are used to detect the tampered region, and the information watermarks which include basic watermark and additional watermark are used to recover image. Then the compound watermarks are inserted into the other blocks based on the new proposed scheme called three level secret-key embedding scheme (TLSES). And then detect the tamper blocks and recover them by the three level tamper detection scheme (TLTDS). The experimental results show that the paper can not only accurately detect the tamper region and recover image, but also can effectively resist mean attack and collage attack.

     

基于小波变换和人类视觉系统的盲数字水印算法

随着因特网的发展,数字水印技术被广泛应用于数字图像、音频、视频等多媒体产品的版权保护。按照水印检测的方式可把数字水印分为盲水印和明文水印。文中提出了一种基于小波变换和人类视觉系统的盲数字水印算法,首先将水印图像利用Arnold混沌映射进行置乱,对宿主图像进行小波分解,然后通过改变两个小波子带相应系数的大小关系来嵌入水印信息。其中对相应小波系数修改权值的设置,利用了基于小波域的人眼视觉系统的特点。提取水印不需要原始图像。实验表明该算法在抵抗JPEG压缩、剪切和盐椒噪声等攻击有比较好的鲁棒性。     

一种基于混沌系统的多功能彩色图像数字水印算法

目前,在某一数字产品中仅仅嵌入一种水印已经不能满足人们的要求,在很多情况下,人们需要的是多重水印或多功能水印。本文基于混沌动力系统良好的随机性和初值敏感性,提出了一种空域和DCT域相结合的针对彩色图像的多功能数字水印算法,该算法在彩色图像的蓝色分量中基于混沌随机密钥和LSB技术重复分块嵌入了一幅半脆弱水印,以实现完整性认证及篡改检测,同时分别在红色分量DCT直流系数(DC)中和绿色分量DCT中频系数中各由混沌密钥控制随机嵌入一幅鲁棒水印,这些水印完成版权认证、附加信息检测等。实验结果表明,该算法较好地实现了多功能水印技术。     

Feature based robust watermarking using image normalization

This paper presents a robust watermarking scheme based on feature point detection and image normalization. Firstly some stable feature points are detected from the original image using the proposed multiresolution feature point detection filter. Then, image normalization is applied to the disks centered at these feature points. The watermark is embedded in the subband coefficients of DFT domain of each disk separately. And the watermark detection uses the correlation between the watermark embedding coefficients and the original watermark, and does not need the original image. The proposed scheme combines the advantages of feature point detection and image normalization, which can achieve strong robustness to signal processing and geometrical distortions. The experimental results also demonstrate good performance of the proposed scheme.     

基于特征点的抗几何攻击水印算法

利用Harris特征点并结合图像的归一化原理提出了一种新的数字水印方案。由于Harris算子的算法简单,稳健性较好,图像的特征点在经过几何攻击后仍然可以保持。而且,归一化的图像对图像的旋转不太敏感,所以首先对每一个以特征点为圆心的互不重叠的圆归一化以确定水印的嵌入点,然后把水印嵌入到原来的图像中,这样,可以很好地解决水印嵌入和检测的同步问题。实验证明,该算法能很好地抵抗如旋转,缩放,剪切等形式的几何攻击与常规信号处理攻击。     

一个基于矢量量化的数字水印算法

文章提出了一个新的基于矢量量化的数字水印算法,与基于DCT(DiscreteCosineTransform)、DFT(DiscreteFourierTransform)及DWT(DiscreteWaveletTransform)等的传统水印算法不同,该算法利用码书分割方法和矢量量化索引的特点,在矢量量化的不同阶段分别嵌入水印来保护原始图像的版权,水印检测不需要原始图像。实验结果表明,该方法实现的水印具有良好的不可见性,并对JPEG压缩、矢量量化压缩、旋转以及剪切等空域操作也具有较好的稳健性。     

Lookup-Table-Based Secure Client-Side Embedding for Spread-Spectrum Watermarks

Today, mass-scale electronic content distribution systems embed forensic tracking watermarks primarily at the distribution server. For limiting the bandwidth usage and server complexity and enhancing scalability, it is preferable to embed the watermark at the client. Embedding in these untrusted clients requires secure embedding methods that do not leak unmarked content or the watermarking secrets. In this work, we propose a secure watermark embedding scheme based on lookup tables for spread-spectrum watermarks, which are robust to noise and can be detected without comparison to the original content. We also develop fast detection mechanisms that make the watermark detection feasible for tracking systems with a large number of clients. Our fast detection algorithm improves detection speed of existing methods by six orders of magnitude in a typical system with millions of clients.      

一种基于小波变换的零水印算法

在水印嵌入的时候,已有的大多数数字水印方法都是对原始图像数据信息作一定的运算修改,使得鲁棒性和安全性受到限制。而零水印不需要修改原始图像的任何信息,可以有更好的透明性。本文提出了一种基于图像置乱和小波变换的零水印算法:首先将水印图像进行置乱,然后利用载体图像一级小波分解后的低频子图和置乱后的水印图像得到提取矩阵,再对提取矩阵进行一定的打乱加密。利用提取矩阵来提取水印,增强了水印的透明性、鲁棒性和安全性。     

GPU-accelerated blind and robust 3D mesh watermarking by geometry image

The prevalence of cheap and powerful consumer level graphics accelerated hardware introduces a significant growth of 3D applications. In this paper, we have proposed a GPU-accelerated blind and robust watermarking approach to the 3D polygon meshes on the basis of the geometry image transform and image watermarking, which performs watermark embedding and detection on the basis of the geometry image derived from a spherical parametrisation of the input mesh with the help of massive-parallel processing power of the GPUs on the display card. The experimental results show that our approach is successful in at least two aspects. First, the watermark is robust, the embedded watermark survives from common geometric attacks, cropping, simplification, and re-meshing attacks. Second, with the help of parallel computations on the GPUs, the embedding and detection process is extremely fast.     

基于YIQ色彩空间的彩色图像盲水印算法*

提出了一种将彩色图像作为数字水印嵌入到彩色宿主图像中的新算法,用于图像版权保护。将彩色水印图像进行一维数字化处理,并将彩色宿主图像由RGB色彩模式转换成YIQ色彩模式,采用整数小波变换将彩色水印嵌入到彩色图像YIQ色彩空间的Y分量中。彩色水印的提取不需要原始水印和原始宿主图像。实验表明：该数字水印算法不仅具有良好的透明性,而且对诸如叠加噪声、JPEG压缩、几何剪切、平滑滤波等攻击具有很强的鲁棒性。     

图像块的自适应均衡水印算法

目的 针对水印算法通常利用实验确定强度参数,实验工作量大并且具有随机性,得到的参数无法较好地均衡水印不可见性和鲁棒性,提出一种基于图像块的自适应均衡水印算法。方法 利用尺度不变特征变换（SIFT）提取原始图像中鲁棒性强的特征点作为水印嵌入区域,将提取的嵌入区域分成4个大小相等且互不重叠的图像块,并对各图像块进行奇异值分解（SVD）,得到与各块相应的奇异值矩阵,各块与水印做一级离散小波变换后产生的各子带相叠加,生成嵌入加密水印块,重组得到水印矩阵,降维后将特征点还原到原始图像。根据果蝇优化算法（FOA）中适应度函数迭代确定加密水印强度参数,构造水印图像的自适应嵌入,来均衡水印的不可见性和鲁棒性,水印检测可直接作用在受攻击后的图像上,无需校正恢复。结果 对标准灰度图像进行多组实验,得到含水印图像峰值信噪比均达到43dB以上;对水印载体图像分别进行噪声、压缩、剪切、旋转仿真攻击实验,提取水印图像与原始水印图像的归一化相关系数都达到0.94以上。结论 SIFT算法实现图像块局部嵌入,提取特征点稳定性强,结合SVD算法使水印嵌入性能良好,利用FOA算法自适应确定最优参数,使水印图像嵌入效果达到最佳状态,最终均衡了水印的不可见性和鲁棒性。     

基于DCT变换的图象分块数字水印算法

数字水印是数字作品版权保护的重要技术手段,不可察觉性和鲁棒性是图象水印中基本要求,但它们却是一对互相制约的因素。该算法提出了一种新的数字水印嵌入和提取方法,以一幅图象作为水印,信息量大,优于通常把文本,字符作为水印的方法;分块随机嵌入提高了水印嵌入的顽健性;根据图象局部特征确定水印的嵌入强度,使水印的嵌入强度随图象局部特征变化而变化。针对典型攻击的实验结果表明该算法具有很好的鲁棒性。