基于离散余弦变换的图像半盲水印技术研究

结合Arnold变换置乱和频谱系数相关性检测方法,提出了一种基于离散余弦变换域频谱系数相关性检测的半盲水印方案。通过不同嵌入强度的仿真实验,结果表明在嵌入强度k为2.5时达到最大嵌入量,其含水印图的峰值信噪比为30.489 2 dB,相似度达到0.998 9。通过攻击测试表明提出的水印方案具有较好的稳健性。综合仿真实验和攻击测试结果,表明提出的水印方案较好的保证了水印的不可感知性、稳健性与水印容量之间的平衡。     

Cryptanalysis and improvement of a chaotic system based fragile watermarking scheme

In this paper, we analyze the security of a chaotic system based fragile watermarking scheme for image tamper detection proposed by Rawat et al. recently. Some errors and modification attack against Rawat et al.’s scheme are demonstrated. Both theoretical analysis and experimental results show that the fragile watermarking scheme is not security. Besides, improvement measure is presented to enhance the security of the fragile watermarking scheme.     

一种基于四又树分割的小波域自适应水印方案

文章提出了一种基于四叉树分割的小波域自适应水印方案。算法根据图像的纹理和细节通过四叉树分割将小波系数划分成大小不等的系数块，引入一个与系数块的性质有关的视觉加权因子，对小波域无损视觉量化模型进行了改进，提高了水印的嵌入强度；通过小波系数的量化选择，将水印信息嵌入到小波域的鲁棒性系数上，提高了水印对抗常规处理的能力。仿真实验结果证明该方案同时具有良好的鲁棒性和透明性。     

抵抗仿射变换攻击的多比特图像水印

目前,大多数鲁棒图像水印所面临的最大问题就是几何攻击,而几何攻击又以仿射变换为主,攻击者只需对目标图像做轻微的几何形变就可以使嵌入其中的水印信息失效。本文在Ping Dong等人提出的基于图像归一化方法的抵抗任意仿射交换攻击的鲁棒数字水印的基础上,改进了原有的归一化方法,去掉了归一化过程中的约束条件,简化了归一化的过程。并且在此基础上提出一种新的水印嵌入方案,克服了文献[1]中水印方案水印不可见性较差的问题。实验证明,本文提出的方案对仿射变换攻击具有很好的鲁棒性,嵌入的水印容量较大且水印图像的质量较高。     

基于四叉树分割的小波域自适应水印方案

文章提出了一种基于四叉树分割的小波域自适应水印方案。算法根据图像的纹理和细节通过四叉树分割将小波系数划分成大小不等的系数块，引入一个与系数块的性质有关的视觉加权因子，对小波域无损视觉量化模型进行了改进，提高了水印的嵌入强度；通过小波系数的量化选择，将水印信息嵌入到小波域的鲁棒性系数上，提高了水印对抗常规处理的能力。仿真实验结果证明该方案同时具有良好的鲁棒性和透明性。     

一种基于四叉树分割的小波域自适应水印方案

文章提出了一种基于四叉树分割的小波域自适应水印方案。算法根据图像的纹理和细节通过四叉树分割将小波系数划分成大小不等的系数块,引入一个与系数块的性质有关的视觉加权因子,对小波域无损视觉量化模型进行了改进,提高了水印的嵌入强度;通过小波系数的量化选择,将水印信息嵌入到小波域的鲁棒性系数上,提高了水印对抗常规处理的能力。仿真实验结果证明该方案同时具有良好的鲁棒性和透明性。     

一种安全的数字音频水印方案

提出一种安全的数字音频水印算法,利用密钥生成的序列作为水印同步码,并在时间域嵌入同步码。水印信息采用分块结构化编码方式,水印分块中采用校验码机制,水印内容采用量化方式嵌入在小波变换域,水印分块在音频段中循环冗余嵌入方式,以抵抗同步攻击的能力。提出的算法不仅具有较好的不可感知性,对低通滤波、噪声、重量化、重采样、MP3压缩等信号处理具有较好的鲁棒性;同时对抵抗随机裁剪攻击、抖动攻击、时间延展等同步攻击具有很好的鲁棒性。     

A Novel Audio Watermarking Algorithm for Copyright Protection of Digital Audio

Digital watermark technology is now drawing attention as a new method of protecting digital content from unauthorized copying. This paper presents a novel audio watermarking algorithm to protect against unauthorized copying of digital audio. The proposed watermarking scheme includes a psychoacoustic model of MPEG audio coding to ensure that the watermarking does not affect the quality of the original sound. After embedding the watermark, our scheme extracts copyright information without access to the original signal by using a whitening procedure for linear prediction filtering before correlation. Experimental results show that our watermarking scheme is robust against common signal processing attacks and it introduces no audible distortion after watermark insertion.     

Optimal audio watermarking scheme using genetic optimization

Designing an optimal audio watermarking system is an open difficult issue since its two basic performance measures, i.e., imperceptibility and robustness, are conflicting with each other. So, an optimal audio watermarking scheme needs to optimally balance both imperceptibility and robustness. In order to realize such an optimal watermarking system, by considering the balance as an optimization problem, we propose an optimal audio watermarking scheme using genetic optimization with variable-length mechanism in this paper. The presented genetic optimization procedure can automatically determine optimal embedding parameters for each audio frame of an audio signal. Specially, employed variable-length mechanism can effectively search most suitable positions for watermark embedding, including suitable audio frames and their AC coefficients. By dint of the genetic optimization with variable-length mechanism, proposed audio watermarking scheme can not only guarantee good quality of watermarked audio signal but also effectively improve its robustness. Experimental results show that proposed watermarking scheme has good imperceptibility and high capability against common signal processing and some desynchronization attacks.     

Visual saliency’s modulatory effect on just noticeable distortion profile and its application in image watermarking

Perceptual watermarking should take full advantage of the results from human visual system (HVS) studies. Just noticeable distortion (JND) gives us a way to model the HVS accurately. In this paper, another very important aspect affecting human perception, visual saliency, is introduced to modulate JND model. Based on the visual saliency’s modulatory effect on JND model which incorporates visual attention’s influence on visual sensitivity, the saliency modulated JND profile guided image watermarking scheme is proposed. The saliency modulated JND profile guided watermarking scheme, where the visual sensitivity model combined with visual saliency’s modulatory effect is fully used to determine image-dependent upper bounds on watermark insertion, allows us to provide the maximum strength transparent watermark. Experimental results confirm the improved performance of our saliency modulated JND profile guided watermarking scheme in terms of transparency and robustness. Our watermarking scheme is capable of shaping lower injected-watermark energy onto more sensitive regions and higher energy onto the less perceptually significant regions in the image, which yields better visual quality of the watermarked image. At the same time, the proposed saliency modulated JND profile guided image watermarking scheme is more robust compared to unmodulated JND profile guided image watermarking scheme.     

基于小波和余弦变换组合的图像水印方案

数字水印作为数字媒体版权保护的有效手段,近几年来在国际上引起了人们极大的兴趣.本文针对数字图像水印进行了研究,提出了一个基于离散小波变换和离散余弦变换组合的图像水印新方案.实验结果表明,该水印方案很好地体现了图像水印的鲁棒性和不可视性间的统一,在相同的水印图像质量条件下,对常规的图像处理和噪声干扰比其它图像水印方案具有更好的鲁棒性.     

一种基于分数傅立叶域图象盲水印方案

利用分数傅立叶变换级次的任意性,提出了一种基于分数傅立叶域图象水印方案。对载体图像进行p级的二维离散分数傅立叶变换,将原始水印图像用LSB算法,嵌入到载体图像的p级分数域的低频系数矩阵中,再进行逆变换得到水印图像。提高了水印安全性,缓解了水印的不可见性与鲁棒性之间的矛盾。仿真试验结果表明该水印具有良好的不可见性和抗噪声攻击性。     

四元数域彩色图像整体式水印算法

该文提出一种结合四元数变换域和四元数分解方法的整体式彩色图像水印算法。首先对彩色载体图像进行分块四元数傅里叶变换得到其频域矩阵,然后对频域单位小块进行四元数奇异值分解,根据分解得到四元数酉矩阵前若干列中对角线元素的幅值构造水印序列,并将水印隐藏到分解得到的实系数奇异值中。仿真实验表明,该文提出的水印方法不仅可以把嵌入水印带来的误差扩散到载体图像的各个颜色分量上,而且比传统的将彩色图像划分为各个单独色彩通道,分别进行水印嵌入的方法不可见性更好,并且,通过构造与奇异值酉矩阵相关的水印序列可以有效解决现有四元数水印算法存在的误检测率以及水印图像易伪造问题。     

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.     

A dual cepstrum-based watermarking scheme with self-synchronization

This study presents a supplementary cepstrum-based scheme to achieve blind audio watermarking via the mean-value manipulation. The proposed scheme can work with the conventional statistical mean manipulation to double the watermark capacity under the same framework. As these two cepstral schemes affect the spectrum in low frequencies in a superposition manner, the developed watermarking system employs the conventional scheme to initiate a start and the new one to actually embed watermark bits. During the embedding phase, the rapid variations between frames caused by the watermarking process are avoided by adding a transition space. In addition, the watermarking system maintains data synchronization through the insertion of a sinusoid-like signal which keeps synchronization with the frame rate. Experimental results confirm the robustness of the proposed scheme against various attacks, including time-scaling and time-shifting that many other watermarking techniques failed to survive through.     

Secure and robust host-adapted color image watermarking using inter-layered wavelet-packets

This work presents a secure and robust color image watermarking for copyright protection applications, that is based on exploiting the multi-spectral properties of the primary color components of the RGB image. The proposed scheme employs the interconnection between the subbands of the primary color components in the wavelet-packet domain. The scheme is constructed to be adaptive, in the sense that the watermark bits are embedded in safe locations, depending on the inter-layer energy of coefficients in the wavelet-packets. The scheme immunity to attacks is improved by applying a two-level security procedure. To validate the high performance of the proposed scheme, several experimental tests were conducted and a comparative analysis was provided. The obtained results have shown improved watermarking robustness against a wide range of attacks while preserving a high watermarking imperceptibility.     

一种基于H.264/AVC的鲁棒性视频水印算法的研究

依据 H.264视频编码标准提出一种视频水印方案。结合H.264帧间预测编码的特点以及人类视觉系统原理,选择P帧宏块中的MV作为水印信息嵌入的对象,对MV进行量化处理,得到两个互相独立的区域。根据水印信息的不同,修改MV,使其指向不同的区域,对其采用扩频技术来实现水印嵌入,以提高水印的鲁棒性。实验结果表明,新方案能够抵抗重编码压缩、加载噪声、旋转等多种攻击,鲁棒性良好。     

扩频水印鲁棒性分析

数字水印的鲁棒性是水印技术实用化的一个重要指标。与通过StirMark测试和各种仿真测试不同,本文定义互信息作为代价函数,建立扩频水印系统鲁棒性描述和度量的一般模型,并对加性扩频水印的鲁棒性进行详细分析,推导出评估鲁棒性的互信息度量计算模型,仿真分析了盲检测和非盲检测条件下互信息函数对鲁棒性的评估结果。实验以统计误比特率的方法计算图像DCT域中低频系数为载体的扩频水印误码率,当水印噪声比变化时,互信息函数和误码率之间的匹配关系验证了互信息度量模型的有效性。互信息函数可以作为代价函数评估水印的鲁棒性,并预测误码率的变化趋势。      

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.     

Data hiding with video independent components

Video watermarking is a main technique for video copyright protection. A novel blind video watermarking scheme is proposed, which embeds a watermark into video independent components by using the four-neighbouring-mean-based method. Temporal synchronisation is achieved efficiently. Simulations show that the scheme is robust to MPEG2 compression and collusion attacks.