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。     

基于归一化和Bessel–Fourier矩的鲁棒水印算法

为了增强水印的抗几何攻击能力,提出了一种基于归一化和Bessel-Fourier矩的鲁棒水印算法。首先对图像进行归一化,使图像的Bessel-Fourier矩具有旋转、缩放和平移(RST)不变性;然后通过使用Bessel-Fourier多项式直接将水印添加到图像的空域强度中,嵌入强度由一个迭代特征修改和验证程序控制,可以避免在水印嵌入和检测过程中引入错误。大量的实验结果表明,本文提出的水印算法对几何攻击以及一般的信号处理具有很好的鲁棒性。     

Image-adaptive watermarking using 2D chirps

Linear chirps, a special case of polynomial phase exponentials, have recently been proposed for digital watermarking. In this work, we propose a known-host-state methodology for designing image watermarks that are robust to compression. We use a two-dimensional frequency-modulated chirp as a spreading function in a block-based spatial watermarking scheme. In each block, the chirp is used to embed binary phase information. Chirp parameters allow for spectral shaping of the watermark to match host content. Since host state is known to the embedder, it is possible to tune the chirp for optimum performance, particularly against compression. In contrast to existing chirp watermarking where only a single watermark is generally embedded, the proposed block chirp watermarking allows for a much higher payload. Detection is done using chirp transform subject to key exchange for security. We show that the proposed method significantly outperforms non-adaptive watermarking across all compression factors under variety of attacks.     

基于奇偶量化的空域抗几何攻击图像水印算法

数字水印对几何攻击的鲁棒性问题一直没有得到很好的解决,该文提出了一种能够抵抗RST(旋转、缩放、平移)攻击,局部剪切以及常规信号处理攻击的多比特图像水印算法。该文利用尺度不变特征变换(SIFT)进行水印信号的同步;设计了一种圆环形的水印模式,并在空域采用奇偶量化嵌入水印;并设计了一种奇偶检测器提取水印。实验结果表明该算法能获得很好的图像质量,且能十分有效地抵抗各种几何攻击以及常规的压缩,滤波等攻击。     

抵抗几何攻击的数字图像水印

该文实现了一种抵抗几何攻击的数字图像水印方案。水印信号为根据密钥产生的服从正态分布的实数序列,对水印信号作预处理并进行周期化之后在空域将其嵌入数字图像中。检测端不需要原始图像,根据预测水印的自相关函数(ACF)判断水印图像遭受的几何变换攻击并进行逆变换,然后进行水印检测。实验表明该方案对压缩、滤波、剪切等常见的图像处理攻击同样具有很高的鲁棒性。     

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.     

Realisation and robustness evaluation of a blind spatial domain watermarking technique

A blind digital image watermarking scheme based on spatial domain is presented and investigated in this paper. The watermark has been embedded in intermediate significant bit planes besides the least significant bit plane at the address locations determined by pseudorandom address vector (PAV). The watermark embedding using PAV makes it difficult for an adversary to locate the watermark and hence adds to security of the system. The scheme has been evaluated to ascertain the spatial locations that are robust to various image processing and geometric attacks JPEG compression, additive white Gaussian noise, salt and pepper noise, filtering and rotation. The experimental results obtained, reveal an interesting fact, that, for all the above mentioned attacks, other than rotation, higher the bit plane in which watermark is embedded more robust the system. Further, the perceptual quality of the watermarked images obtained in the proposed system has been compared with some state-of-art watermarking techniques. The proposed technique outperforms the techniques under comparison, even if compared with the worst case peak signal-to-noise ratio obtained in our scheme.     

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.     

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.     

Digital watermarking robust to geometric distortions.

In this paper, we present two watermarking approaches that are robust to geometric distortions. The first approach is based on image normalization, in which both watermark embedding and extraction are carried out with respect to an image normalized to meet a set of predefined moment criteria. We propose a new normalization procedure, which is invariant to affine transform attacks. The resulting watermarking scheme is suitable for public watermarking applications, where the original image is not available for watermark extraction. The second approach is based on a watermark resynchronization scheme aimed to alleviate the effects of random bending attacks. In this scheme, a deformable mesh is used to correct the distortion caused by the attack. The watermark is then extracted from the corrected image. In contrast to the first scheme, the latter is suitable for private watermarking applications, where the original image is necessary for watermark detection. In both schemes, we employ a direct-sequence code division multiple access approach to embed a multibit watermark in the discrete cosine transform domain of the image. Numerical experiments demonstrate that the proposed watermarking schemes are robust to a wide range of geometric attacks.     

Robust authentication scheme for protecting copyrights of imagesand graphics

Watermarking techniques are primarily used for copyright protection. A simple and robust watermark-like digital authentication scheme is proposed. This work has two major merits. First, the watermark used in the proposed authentication scheme is the same type used in the original image, e.g. grey level images. Second, the proposed scheme meets the requirements for watermarking techniques. Illegal users cannot perceive and break the watermark signed from the original image. Furthermore, the signed watermark is robust against attacks by many image altering algorithms, such as filtering, lossy compression, rotation and scaling. The proposed scheme is not only suitable for ordinary natural images, but also for cartoon graphics     

一种可抵抗几何攻击的Directionlet变换域盲水印算法

抵抗几何攻击是数字水印研究领域具有挑战性的课题。该文提出一种利用Directionlet变换构造水印同步信息的盲水印算法:通过边缘检测算子锁定图像边缘;利用拉格朗日定理求取边缘斜率;选取两条边缘,用其斜率构成Directionlet变换的采样矩阵;在Directionlet变换域内自适应嵌入水印,排除几何攻击对水印检测的影响。仿真实验结果表明,该算法抵抗旋转等几何攻击具有很好的鲁棒性能。     

一种基于余数判决的数字水印算法

本文给出了一种新型的鲁棒水印算法.首先选择一个混沌映射来置换水印数据和载体图像,以取得很好的置换效果.与现有其它空间域算法不同,本方案不直接修改单个象素的灰度值,而是根据提出的严格余数条件,重新设置载体图像象素间的灰度关系以实现水印数据的嵌入.并根据余数判决准则,利用基于空间域的纠错技术进行水印提取.仿真实验表明,该水印算法在保证载体图像质量的同时,具有较强的鲁棒性:在用JPEG将载体图像压缩到27.4%时仍能提出可识别的水印信息,并且能有效地抵抗加性高斯白噪声的干扰,在同步条件下对剪切、缩放、旋转等几何攻击也具有较好的鲁棒性.     

Discrete Multiwavelet–Based Video Watermarking Scheme Using SURF

This paper proposes a robust, imperceptible block‐based digital video watermarking algorithm that makes use of the Speeded Up Robust Feature (SURF) technique. The SURF technique is used to extract the most important features of a video. A discrete multiwavelet transform (DMWT) domain in conjunction with a discrete cosine transform is used for embedding a watermark into feature blocks. The watermark used is a binary image. The proposed algorithm is further improved for robustness by an error‐correction code to protect the watermark against bit errors. The same watermark is embedded temporally for every set of frames of an input video to improve the decoded watermark correlation. Extensive experimental results demonstrate that the proposed DMWT domain video watermarking using SURF features is robust against common image processing attacks, motion JPEG2000 compression, frame averaging, and frame swapping attacks. The quality of a watermarked video under the proposed algorithm is high, demonstrating the imperceptibility of an embedded watermark.     

Screen-shooting resistant image watermarking based on lightweight neural network in frequency domain

Currently, digital mobile devices, especially smartphones, can be used to acquire information conveniently through photograph taking. To protect information security in this case, we propose an efficient screen-shooting resistant watermarking scheme via deep neural network (DNN) in the frequency domain to achieve additional information embedding and source tracing. Specifically, we enhance the imperceptibility of watermarked images and the robustness against various attacks in real scene by computing the residual watermark message and encoding it with the original image using a lightweight neural network in the DCT domain. In addition, a noise layer is designed to simulate the photometric and radiometric effects of screen-shooting transfer. During the training process, the enhancing network is used to highlight the coding features of distorted images and improve the accuracy of extracted watermark message. Experimental results demonstrate that our scheme not only effectively ensures the balance between the imperceptibility of watermark embedding and the robustness of watermark extraction, but also significantly improves computational efficiency compared with some state-of-the-art schemes.     

基于小波变换和相对量化的图像数字水印算法

提出了一种基于分块小波变换和相对量化的图像数字水印算法。由于在算法中采用了量化嵌入策略,从而在提取水印时无需原始图像和原始水印。实验结果表明,该算法对嵌入的水印具有很好的透明性,对亮度和对比度调整攻击具有非常强的稳健性,对JPEG压缩、重采样、颜色抖动、平滑和加噪声等常见的图像处理攻击具有很强的稳健性,并且算法思想简单、步骤简便和容易实现。     

Utilizing neighborhood coefficient correlation: a new image watermarking technique robust to singular and hybrid attacks

A new blind digital image watermarking algorithm with watermark embedded in discrete cosine transform (DCT) coefficients is presented in this paper. The proposed scheme exploits correlation between DCT coefficients in neighborhood blocks for embedding. The watermark is embedded by modifying two DCT coefficients, one pertaining to a block in which watermark bit (0 or 1) is to be embedded and the other corresponding to the selected neighborhood block. Both the selected coefficients are modified by a modification factor so that the difference between the pair of coefficients is brought to a predefined zone. This difference between two DCT coefficients is used to extract watermark. The proposed technique has been tested for different attacks like JPEG compression, rotation, cropping, filtering, gaussian noise, salt and pepper noise, histogram equalization etc. It has been observed that the scheme is highly robust not only for the above mentioned attacks used singularly, but also for different possible combinations of simultaneous attacks. A comparison of the proposed technique with some state of art existing algorithms reveals that our scheme provides better results in terms of quality of watermarked images, payload and robustness.     

基于QR码的Contourlet域数字水印算法

针对目前数字水印技术无法有效抵抗几何攻击的问题,本文提出了一种基于QR码的Contourlet域数字水印算法。将文字信息进行QR码编码作为水印信息。首先,将载体图像进行Contourlet变换;然后,将得到的低频逼近图像进行分块;最后,将每一位QR码水印信息以量化的方式对应嵌入到每一个子块中。实验结果表明,本算法可以抵抗任意角度旋转和任意等比例缩放攻击,同时对高斯噪声、Speckle噪声、均值滤波、高斯滤波和JPEG压缩攻击具有很强的鲁棒性,并且算法复杂度低;水印提取时不需要借助原始图像,属于盲水印。因此,本文提出的数字水印技术可以广泛应用在数字产品的版权保护中。     

Wavelet tree quantization for copyright protection watermarking

This paper proposes a wavelet-tree-based blind watermarking scheme for copyright protection. The wavelet coefficients of the host image are grouped into so-called super trees. The watermark is embedded by quantizing super trees. The trees are so quantized that they exhibit a large enough statistical difference, which will later be used for watermark extraction. Each watermark bit is embedded in perceptually important frequency bands, which renders the mark more resistant to frequency based attacks. Also, the watermark is spread throughout large spatial regions. This yields more robustness against time domain geometric attacks. Examples of various attacks will be given to demonstrate the robustness of the proposed technique.     

Localized image watermarking in spatial domain resistant to geometric attacks

Watermark robustness to geometric attacks is still a challenging research field. In this paper, a novel robust image watermarking scheme is proposed for resisting such attacks. Watermark synchronization is first achieved by local invariant regions which can be generated using scale normalization and image feature points. The watermark is embedded into all the local regions repeatedly in spatial domain. During embedding, each circular region is first divided into homocentric cirque regions. Then the watermark bits are embedded by quantizing each cirque region into an “odd” or “even” region using odd–even quantization. In the decoder, an odd–even detector (OED) is designed to extract the watermark from the distorted image directly. Localized embedding achieves good invisibility and repeated insertion enhances watermark robustness. Simulation results show that the proposed scheme is robust to both geometric attacks and traditional signal processing attacks.