Performance analysis for geometrical attack on digital image watermarking

We present a technique for irreversible watermarking approach robust to affine transform attacks in camera, biomedical and satellite images stored in the form of monochrome bitmap images. The watermarking approach is based on image normalisation in which both watermark embedding and extraction are carried out with respect to an image normalised to meet a set of predefined moment criteria. The normalisation procedure is invariant to affine transform attacks. The result of watermarking scheme is suitable for public watermarking applications, where the original image is not available for watermark extraction. Here, direct-sequence code division multiple access approach is used to embed multibit text information in DCT and DWT transform domains. The proposed watermarking schemes are robust against various types of attacks such as Gaussian noise, shearing, scaling, rotation, flipping, affine transform, signal processing and JPEG compression. Performance analysis results are measured using image processing metrics.     

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.     

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。     

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.     

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。     

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.     

A new robust digital image watermarking based on Pseudo-Zernike moments

A robust digital image watermarking scheme based on Pseudo-Zernike moments and image normalization is proposed. The goal is to resist both geometric distortion and common signals processing. We construct the geometrically invariant space by using image normalization. The Pseudo-Zernike moments of the normalized image are computed, and some low-order Pseudo-Zernike moments are selected. We embed digital watermark into the host image by quantizing the magnitudes of the selected Pseudo-Zernike moments. Numerical experiments demonstrate that the proposed watermarking scheme is robust to a wide range of geometric attacks and common signals processing.     

Security analyses of the watermarking scheme based on redundant discrete wavelet transform and singular value decomposition

This study analyzes the recent image watermarking schemes based on redundant discrete wavelet transform (RDWT) and singular value decomposition (SVD), and shows that in fact they are insecure and cannot be used for protecting the rightful ownership. The RDWT-SVD watermarking directly embeds a grayscale watermark image of the same size with the host image into the singular value matrix of the RDWT-transformed host image, then produces the left and right orthogonal matrices as side information which is later used in the watermark extraction stage. The RDWT-SVD approach enjoys the advantage of the RDWT redundancy to achieve a high embedding capacity, and preserves the watermark imperceptibility by exploiting the SVD stability properties. It is claimed that RDWT-SVD watermarking is robust against several common image processing and geometrical attacks, yet a fundamental flaw in the RDWT-SVD scheme is found, which leads to severe the false positive issue. Three vulnerable attacks should be considered in the RDWT-SVD scheme: (1) An attacker can easily claim the owner watermarked image; (2) the owner has the ambiguity because of the wrong side information usage, and (3) the owner can extract the correct watermark from arbitrary image. Thus, it is important to highlight these attacks when implementing the RDWT-SVD watermarking scheme.     

Robust image watermarking based on multiband wavelets and empirical mode decomposition.

In this paper, we propose a blind image watermarking algorithm based on the multiband wavelet transformation and the empirical mode decomposition. Unlike the watermark algorithms based on the traditional two-band wavelet transform, where the watermark bits are embedded directly on the wavelet coefficients, in the proposed scheme, we embed the watermark bits in the mean trend of some middle-frequency subimages in the wavelet domain. We further select appropriate dilation factor and filters in the multiband wavelet transform to achieve better performance in terms of perceptually invisibility and the robustness of the watermark. The experimental results show that the proposed blind watermarking scheme is robust against JPEG compression, Gaussian noise, salt and pepper noise, median filtering, and ConvFilter attacks. The comparison analysis demonstrate that our scheme has better performance than the watermarking schemes reported recently.     

Rotation, scaling and translation invariant image watermarking using feature points

In this article, a novel robust image watermarking scheme is presented to resist rotation, scaling, and translation （RST）. Initially, the original image is scale normalized, and the feature points are then extracted. Furthermore, the locally most stable feature points are used to generate several nonoverlapped circular regions. These regions are then rotation normalized to generate the invariant regions. Watermark embedding and extraction are implemented in the invariant regions in discrete cosine transform domain. In the decoder, the watermark can be extracted without the original image. Simulation results show that the proposed scheme is robust to traditional signal processing attacks, RST attacks, as well as some combined attacks.     

Hiding digital watermarks using multiresolution wavelet transform

In this paper, an image accreditation technique by embedding digital watermarks in images is proposed. The proposed method for the digital watermarking is based on the wavelet transform. This is unlike most previous work, which used a random number of a sequence of bits as a watermark and where the watermark can only be detected by comparing an experimental threshold value to determine whether a sequence of random signals is the watermark. The proposed approach embeds a watermark with visual recognizable patterns, such as binary, gray, or color image in images by modifying the frequency part of the images. In the proposed approach, an original image is decomposed into wavelet coefficients. Then, multi-energy watermarking scheme based on the qualified significant wavelet tree (QSWT) is used to achieve the robustness of the watermarking. Unlike other watermarking techniques that use a single casting energy, QSWT adopts adaptive casting energy in different resolutions. The performance of the proposed watermarking is robust to a variety of signal distortions, such as JPEG, image cropping, sharpening, median filtering, and incorporating attacks     

Contourlet-based image adaptive watermarking

In the contourlet transform (CT), the Laplacian pyramid (LP) decomposes an image into a low-frequency (LF) subband and a high-frequency (HF) subband. The LF subband is created by filtering the original image with 2-D low-pass filter. However, the HF subband is created by subtracting the synthesized LF subband from the original image but not by 2-D high-pass filtering the original image. In this paper, we propose a contourlet-based image adaptive watermarking (CIAW) scheme, in which the watermark is embedded into the contourlet coefficients of the largest detail subbands of the image. The transform structure of the LP makes the embedded watermark spread out into all subbands likely in which the LF subbands are included when we reconstruct the watermarked image based on the watermarked contourlet coefficients. Since both the LF subbands and the HF subbands contain watermarking components, our watermarking scheme is expected to be robust against both the LF image processing and the HF image processing attacks. The corresponding watermarking detection algorithm is proposed to decide whether the watermark is present or not by exploiting the unique transform structure of LP. With the new proposed concept of spread watermark, the watermark is detected by computing the correlation between the spread watermark and the watermarked image in all contourlet subbands fully. The proposed CIAW scheme is particularly superior to the conventional watermarking schemes when the watermarked image is attacked by some image processing methods, which destroy the HF subbands, thanks to the watermarking components preserved in the LF subbands. Experimental results show the validity of CIAW in terms of both the watermarking invisibility and the watermarking robustness. In addition, the comparison experiments prove the high-efficiency of CIAW again.     

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。     

Geometrically invariant image watermarking based on fast Radial Harmonic Fourier Moments

In order to reduce the time complexity and improve the reconstruction performance of traditional method for Radial Harmonic Fourier Moments (RHFMs), we introduce a fast and precise method by using FFT and based on the which, this paper proposes a novel image watermarking algorithm which is robust to geometric attacks. We firstly compute the RHFMs of the original image by using the proposed method and select the robust RHFMs which are suitable for watermark embedding. Then the watermark is embedded by modifying the magnitudes of RHFMs based on quantization. In the decoder, the watermark can be extracted from the magnitudes of RHFMs directly without using the original image. Simulation results show the proposed algorithm provides an excellent watermark invisibility and can be resilient to geometric attacks and common image processing attacks effectively.     

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。     

采用几何校正优化的轮廓波水印算法

针对目前的图像水印难以同时抵抗常规攻击和几 何攻击的不足,提出一种新的轮廓波 水印算法。水印嵌入阶段,该方法将宿主图像进行离散小波变换和非下采样轮廓波变换,并 将水印嵌入到熵值最大的高频子带,解决了将水印嵌入低频无法抵抗几何攻击及高频不能 很好抵抗滤波等常规攻击的问题。在水印嵌入前对嵌入区域进行加密处理,提高算法的安全 性。水印提取阶段,利用Zernike矩对含水印图像进行几何校正再进行提取,进一步提高了 算法的抗几何攻击能力。最后利用峰值信噪比和归一化系数对算法进行评价,验证算法的不 可感知性和鲁棒性。仿真实验结果表明,算法在不同的宿主图像和水印图像上均表现良好。 该算法在具有较好不可见性的基础上,除了对常规攻击具有很好的抵抗力,对几何攻击也具 有强鲁棒性,归一化系数(normalization coefficient,NC)均达到了0.99     

基于支持向量回归的Contourlet域盲水印算法

为进一步提高基于支持向量机(SVM,support vector machine)水印算法的性能,提出了基于支持向量回归(SVR,support vector regression)的Contourlet域盲水印算法。首先对宿主图像进行Contourlet分解,然后利用SVM建立图像尺度内的局部相关性模型,根据模型的预测结果自适应地嵌入水印。实验结果表明,所提出的算法不仅具有较好的不可感知性,而且对叠加噪声、JPEG压缩、锐化、平滑滤波和对比度增强等常规图像信号处理以及旋转、剪切等几何攻击均具有较好的鲁棒性,其性能明显优于基于SVM的空间域和小波域的水印算法。     

A Robust Watermarking Scheme Using Sequency-ordered Complex Hadamard Transform

This paper presents a robust phase watermarking scheme for still digital images based on the sequency-ordered complex Hadamard transform (SCHT). The transform matrix of the SCHT exhibits sequency ordering which is analogous to frequency in the discrete Fourier transform (DFT). Hence, sequency-based image analysis can be performed for image watermarking while providing simple implementation and with less computational complexity for computation of the transform. As the SCHT coefficients are complex numbers which consist of both magnitudes and phases, they are suited to adopt phase modulation techniques to embed the watermark. In this proposed scheme, the phases of the SCHT coefficients in the sequency domain are altered to convey the watermark information using the phase shift keying (PSK) modulation. Low amplitude block selection (LABS) is used to enhance the imperceptibility of digital watermark, and amplitude boost (AB) method is employed to improve the robustness of the watermarking scheme. Spread spectrum (SS) technique is adopted to increase the security of watermark against various unintentional or intentional attacks. In order to demonstrate the effectiveness of the proposed watermarking scheme, simulations are conducted under various kinds of attacking operations. The results show that the proposed scheme is able to sustain a series of attacks including common geometric transformations such as scaling, rotating, cropping, painting, and common image-processing operations such as JPEG compression, low-pass filtering, sharpening, noising and phase perturbation, etc. Comparisons of the simulation results with the other schemes are also mentioned and the results reveal that the proposed scheme shows better robustness.     

基于Baker映射与时空混沌相结合的CT-QR域双彩色鲁棒盲水印算法

针对彩色水印图像的盲提取算法抗几何攻击鲁棒性不强的问题,提出一种Baker映射与时空混沌相结合的轮廓波变换(Contourlet transform,CT)和QR分解双彩色强鲁棒盲水印算法。首先将彩色水印分离成RGB分量,对三个分量分别进行Baker映射与时空混沌相结合的预处理操作,然后对载体图像的RGB分量分别进行Contourlet变换,分块QR分解得到酉矩阵,最后根据嵌入规则将加密后的水印分通道的嵌入到酉矩阵中。水印提取时利用Radon变换对图像进行几何校正可提高其几何攻击的鲁棒性。仿真结果表明,该算法不仅使嵌入水印后的图像具有良好的不可见性,而且能有效抵抗加噪、滤波、JPEG压缩、剪切、平移、旋转、马赛克、篡改等攻击,NC值均在0.9以上,对组合攻击也有较强的鲁棒性。      

Secure watermarking scheme against watermark attacks in the encrypted domain

The homomorphic cryptosystems create a great opportunity for secure signal processing (SSP). Watermarking in the encrypted domain provides a promising solution to the security of watermarking. However, the robust performance of the watermarking scheme in the encrypted domain should be carefully considered. In this paper, we propose a robust watermarking scheme in the encrypted domain, which protects the original images from the third party embedders. The hybrid discrete wavelet transform (DWT) and discrete cosine transform (DCT) based method improves the robust performance of the encrypted domain watermarking scheme. The watermark extraction can be performed on both the plaintext and the encrypted domains. We also give an estimation of the expanding factor after watermark embedding in the encrypted domain. At last, we discuss the watermark attacks that are available in the encrypted domain. Taking Haar wavelet transform for example, we conduct the experiments on the visual quality and the robustness of our watermarking scheme, which demonstrate that the entire performance is satisfactory.