基于子块区域分割和自嵌入技术的全盲多功能图像水印算法

利用子块区域分割思想和自嵌入技术提出了一种只利用攻击图像就能进行版权鉴别和内容认证的全盲多功能图像水印算法。将原始图像分割成不重叠的子块,对每个子块进行离散余弦变换,将每个子块离散余弦变换矩阵分成为区域1和区域2两部分,然后对区域1进行奇异值分解,通过判断奇异值均值的最高位数字奇偶性产生特征水印,然后通过调整区域2的2个离散余弦变换交流系数大小自嵌入特征水印,最后对每个子块进行逆离散余弦变换得到含水印图像。算法通过结合将区域1产生的特征水印自嵌入区域2和在区域2盲提取认证水印实现全盲检测和多功能。实验结果表明,算法既能实现版权保护又能实现内容认证,而且还具有区分恶意篡改和无意篡改的能力。     

用于图像篡改定位和恢复的分层半脆弱数字水印算法

设计并实现了一种基于分层的半脆弱数字水印算法,用于图像内容完整性认证,篡改定位和恢复。在嵌入方,将水印信息嵌入到原始图像所有像素的2bit最低有效比特,其中认证水印由奇偶校验码和块与子块之间灰度平均值的比较组成;恢复水印为环面自同构映射块的平均灰度值。在检测方,采用分层思想,分3层对水印进行篡改定位和恢复。实验结果表明,该算法对局部发生的篡改可以有效地检测,精确定位并进行内容恢复,同时能够有效的抵抗矢量量化攻击。     

基于混沌置乱的分块自嵌入水印算法

针对分块自嵌入水印算法的安全性和不能有效判断图像篡改块的问题,提出一种基于混沌置乱的分块自嵌入算法.该算法将由图像块生成的水印按空间位置生成二值水印图像,利用混沌序列对其置乱加密后嵌入到图像的最低位,认证时根据设定的阈值能有效定位图像内容被篡改的图像块.实验仿真和理论分析表明,该算法在保持原算法篡改恢复效果的基础上,无论是否有水印被改变,均能有效判断图像内容被篡改的图像块,且具有更高的安全性.     

A feature-based digital watermarking scheme for halftone image

It is a challenging work to design a robust halftone image watermarking scheme against desynchronization attacks. In this paper, we propose a feature-based digital watermarking method for halftone images with low computational complexity, good visual quality and reasonable resistance toward desynchronization attacks. Firstly, the feature points are extracted from host halftone image by using multi-scale Harris–Laplace detector, and the local feature regions (LFRs) are constructed according to the feature scale theory. Secondly, discrete Fourier transform (DFT) is performed on the LFRs, and the embedding positions (DFT coefficients) are selected adaptively according to the magnitude spectrum information. Finally, the digital watermark is embedded into the LFRs by quantizing the magnitudes of the selected DFT coefficients. By binding the watermark with the geometrically invariant halftone image features, the watermark detection can be done without synchronization error. Simulation results show that the proposed scheme is invisible and robust against common signals processing such as median filtering, sharpening, noise adding, and JPEG compression, etc., and desynchronization attacks such as rotation, scaling, translation (RST), cropping, local random bend, and print-scan, etc.     

一种新颖的用于图像内容认证、定位和恢复的半脆弱数字水印算法研究

 本文提出了一种半脆弱,分块和基于内容的数字水印技术。该算法可以准确的实现篡改区域的认证,定位和恢复。算法基于独立分块技术将用于认证的水印比特嵌入到每个块的Slant变换域的中频区域。嵌入过程是基于我们通过实验发现大部分的Slant中频系数的正负符号在非恶意操作前后保持不变这一性质。在恢复系统中,恢复比特来源于原图压缩后的数据并将此数据嵌入到图像的最低有效位以实现自恢复。认证度由虚警检测率和误警检查率测定。仿真实验表明我们的算法能够准确的检测和定位出篡改区域并能实现篡改区域的近似恢复。另外,与基于DCT和PST变换的算法相比,我们的算法能够更有效的抵抗一些恶意和非恶意操作同时实施的操作。     

Counterfeiting attacks on oblivious block-wise independentinvisible watermarking schemes

We describe a class of attacks on certain block-based oblivious watermarking schemes. We show that oblivious watermarking techniques that embed information into a host image in a block-wise independent fashion are vulnerable to a counterfeiting attack. Specifically, given a watermarked image, one can forge the watermark it contains into another image without knowing the secret key used for watermark insertion and in some cases even without explicitly knowing the watermark. We demonstrate successful implementations of this attack on a few watermarking techniques that have been proposed in the literature. We also describe a possible solution to this problem of block-wise independence that makes our attack computationally intractable.     

Recover the tampered image based on VQ indexing

In this paper, a tampered image recovery scheme is proposed by creating an index table of the original image via vector quantization (VQ) and embedding it into the original image as a basis for recovery. In order to complete the goal of image authentication and recovery, Wong's watermarking scheme [P.W. Wong, N. Memon, Secret an public key image watermarking schemes for image authentication and ownership verification, IEEE Trans. Image Process 10 (10) (2001) 1593–1601] is employed to perform tamper detection. Wong's watermarking scheme can be used to accurately locate tampered regions. If an image has been tampered, the index table can be used to recover the tampered regions. The experimental results indicate that our scheme has the higher probability of image recovery. Besides, compared with Lee and Lin's [Dual watermark for image tamper detection and recovery, Pattern Recognition 41 (2008) 3497–3506] scheme, our scheme provides not only a better quality of recovered images but also better results at edge regions.     

A self-embedding secure fragile watermarking scheme with high quality recovery

In recent years, with the development of cloud storage, more and more people upload images to the cloud for storage. However, confidentiality and integrity issues may arise during transmission and storage to the cloud. Aiming at these security problems, a fragile watermarking scheme based on the encrypted domain is proposed. A watermark is divided into two types, one is for detection, the other is for recovery. After embedding the two types of watermarks into the host image, the watermarked image will be transferred to the cloud for storage. A three-level tamper detection mechanism is used in the detection process, and the first-level tamper detection can be processed in the cloud. While in recovery process, a mechanism of “block-level detection, pixel-level recovery” is proposed to recover the tampered area. The experimental results show that the watermarked image has greatly changed the original image and guarantees the confidentiality. The three-level tamper detection mechanism can accurately detect the tampered area, the image can be effectively restored in different situations, when the tampering rate is as high as 80%, the average PSNR reaches 34.62 dB, and the average SSIM is higher than 0.93.     

Fragile watermarking using finite field trigonometrical transforms

Fragile digital watermarking has been applied for authentication and alteration detection in images. Utilizing the cosine and Hartley transforms over finite fields, a new transform domain fragile watermarking scheme is introduced. A watermark is embedded into a host image via a blockwise application of two-dimensional finite field cosine or Hartley transforms. Additionally, the considered finite field transforms are adjusted to be number theoretic transforms, appropriate for error-free calculation. The employed technique can provide invisible fragile watermarking for authentication systems with tamper location capability. It is shown that the choice of the finite field characteristic is pivotal to obtain perceptually invisible watermarked images. It is also shown that the generated watermarked images can be used as publicly available signature data for authentication purposes.     

一种用于图像篡改定位与恢复的双水印算法

引入虚拟水印的概念,结合自恢复技术,小波变换等水印技术,提出了一种新的数字图像双水印嵌入算法。文中将原图像二次小波变换后的低频分量LL₂作为第一重水印,将数字产品公司标识作为第二重水印,同时利用双水印技术所特有的属性,在两重水印之间构筑函数关系,将其结合在一起。实验结果表明,该算法简单高效,可同时具有水印恢复、版权认证和篡改区定位恢复等多方面的功能。     

Joint halftoning and watermarking

A framework to jointly halftone and watermark a grayscale images is presented. The framework needs the definition of three components: a human visual system (HVS)-based error metric between the continuous-tone image and a halftone, a watermarking scheme with a corresponding watermark detection measure, and a search strategy to traverse the space of halftones. We employ the HVS-based error metric used in the direct binary search (DBS) halftoning algorithm, and we use a block-based spread spectrum watermarking scheme and the toggle and swap search strategy of DBS. The halftone is printed on a desktop printer and scanned using a flatbed scanner. The watermark is detected from the scanned image and a number of post-processed versions of the scanned image, including one restored in Adobe PhotoShop. The results show that the watermark is extremely resilient to printing, scanning, and post-processing; for a given baseline image quality, joint optimization is better than watermarking and halftoning independently. For this particular algorithm, the original continuous-tone image is required to detect the watermark.     

SYNCHRONIZATION RECOVERY SCHEME IN WATERMARKING DETECTION

Most proposed digital watermarking algorithms are sensitive to geometric attacks because the synchronization information of watermark embedding and detection is destroyed. In this letter a novel synchronization recovery scheme based on image normalization is proposed. The presented scheme does not require the original image and can be applied to various watermark systems. A wavelet-based watermarking scheme is proposed as an example and experimental results show that it is robust to geometric attacks.     

一种基于HVS的图像易碎水印

作为多媒体认证和篡改检测的一种新技术,易碎水印正得到越来越多的关注.基于小波变换,结合量化调制过程,本文提出了一个易碎水印算法.该算法具有以下特点:(1)构造水印金字塔,便于实现水印的多分辨率检测;(2)结合视觉特性量化调制,尽可能减小视觉失真;(3)结合图像融合技术的多分辨率检测,使检测结果更准确;(4)抵抗一定程度的JPEG有损压缩.为了实现篡改的检测,本文给出了一个攻击判别方案,以区分恶意攻击和偶然攻击.实验表明,嵌入的水印在脆弱性和鲁棒性上达到了较好的统一,能够抵抗一定程度的压缩而不影响篡改检测的精确性.     

A novel robust logo watermarking scheme using fractional M-band wavelet transform

Digital watermarking, means of hiding/inserting a message, which can be an image, audio, video or text within the digital media. This hidden/inserting message can be later being extracted or detected for a variety of purposes. In this paper, a novel multi-resolution logo watermarking scheme using fractional M-band wavelet transform (Fr-M-band-WT) is proposed. The watermark is embedded in the multiresolution Fr-M-band-WT coefficients of low frequency bands of the host image using singular value decomposition (SVD). A multi-resolution nature of Fr-M-band-WT is exploited in the process of edge detection. Experimental results of the proposed logo watermarking scheme are compared with the previously available watermarking algorithms, fractional Fourier transform (FrFT), fractional wavelet transform (FrWT). Further, the proposed watermark extraction scheme is also tested on different attacks. The results after being investigated the proposed watermarking scheme shows a significant improvement as compared to other existing methods.     

Fragile watermarking scheme for tamper localization in images using logistic map and singular value decomposition

This paper presents a fragile watermarking scheme for tamper localization using Singular Value Decomposition (SVD) and logistic map. The proposed scheme divides the image into blocks of size 2 × 2 pixels and generates an 8-bit watermark from each block. The watermark is computed by permuting the six Most Significant Bits (MSBs) of each pixel in the block using the logistic map, followed by SVD. To secure, the watermark thus generated is further encrypted using the logistic map. This encrypted watermark is embedded into 2 Least Significant Bits (LSBs) of each pixel to enable tamper detection and localization. The experimental results demonstrate that the proposed scheme can precisely locate tampered regions under copy-paste, content removal, text addition, noise addition, vector quantization, collage, content only, and constant feature attacks. Tamper localization accuracy is better or comparable to the state-of-the-art tamper localization algorithms.     

Robust digital watermarking algorithm based on continuous hyperchaotic system and discrete wavelet transform

Many digital watermarking methods have been pro-posedin the last fewyears[1 ,3].It is a tradeoff problemsince whenthe robustness of a watermarkincreases ,theperceptual quality of the contents will be degraded.Hence,the main goal of i mproving a watermarki…     

基于HVS的小波域图像易损水印

基于小波变换,结合量化调制过程,论文提出了一种易损水印算法。该算法具有构造分层水印,便于实现水印的多分辨率嵌入;结合视觉特性量化调制,尽可能减小视觉失真;结合图像融合技术的多分辨率检测,使检测结果更准确;以技抵抗一定程度的JPEG有损压缩等特点。实验表明,嵌入的水印在易损性和鲁棒性上达到了较好的统一,能够抵抗一定程度的压缩而不影响篡改检测的精确性。     

Dual domain watermarking for authentication and compression of cultural heritage images

This paper proposes an approach for the combined image authentication and compression of color images by making use of a digital watermarking and data hiding framework. The digital watermark is comprised of two components: a soft-authenticator watermark for authentication and tamper assessment of the given image, and a chrominance watermark employed to improve the efficiency of compression. The multipurpose watermark is designed by exploiting the orthogonality of various domains used for authentication, color decomposition and watermark insertion. The approach is implemented as a DCT-DWT dual domain algorithm and is applied for the protection and compression of cultural heritage imagery. Analysis is provided to characterize the behavior of the scheme under ideal conditions. Simulations and comparisons of the proposed approach with state-of-the-art existing work demonstrate the potential of the overall scheme.     

Digital watermarking for telltale tamper proofing andauthentication

In this paper, we consider the problem of digital watermarking to ensure the credibility of multimedia. We specifically address the problem of fragile digital watermarking for the tamper proofing of still images. Applications of our problem include authentication for courtroom evidence, insurance claims, and journalistic photography. We present a novel fragile watermarking approach which embeds a watermark in the discrete wavelet domain of the image by quantizing the corresponding coefficients. Tamper detection is possible in localized spatial and frequency regions. Unlike previously proposed techniques, this novel approach provides information on specific frequencies of the image that have been modified. This allows the user to make application-dependent decisions concerning whether an image, which is JPEG compressed for instance, still has credibility. Analysis is provided to evaluate the performance of the technique to varying system parameters. In addition, we compare the performance of the proposed method to existing fragile watermarking techniques to demonstrate the success and potential of the method for practical multimedia tamper proofing and authentication     

基于几何矩的抵抗RST攻击的数字图像水印

目前大多数的数字图像水印方案不能有效抵抗几何形变的攻击,这一弱点已成为数字水印技术走上商用的瓶颈。在各种几何形变中,RST(旋转、缩放、平移)是最为常见的攻击方式。该文提出了一种具有普适性的能够抵抗RST攻击的多比特数字图像水印方案,采用的主要措施有:(1)提出一种基于几何矩的图像标准化方案以抵抗几何攻击;(2)采用扩谱方法构造二维CDMA水印信号,实现多比特水印嵌入;(3)根据HVS特性自适应调整水印的嵌入强度,在鲁棒性和不可见性之间达到平衡;(4)利用MAP和相关方法估计和检测水印信号。实验表明该方案对RST具有很高的鲁棒性,对压缩、滤波等常见的图像处理攻击同样具有良好的鲁棒性。