A blind DCT based color watermarking algorithm for embedding multiple watermarks

Multiple watermarking based techniques are receiving more attention in recent times for its wide variety of applications in different fields. To protect the copyright ownership and validate the authenticity of multiple owners, in this paper a color multiple watermarking method based on DCT (Discrete Cosine Transform) and repetition code is proposed and simulated. Initially, green and blue components of color host image are selected for inserting multiple watermarks. Then, each green and blue component of the image is decomposed into non overlapping blocks and subsequently DCT is employed on each block. In this technique, a binary bit of watermark is embedded into green/blue component’s transformed block by modifying some middle significant AC coefficients using repetition code. During multiple watermarks embedding in green and blue components of the proposed method, DC and some higher AC coefficients are kept intact after zigzag scanning of each DCT block to ensure the imperceptibility of the watermarked host image. The proposed scheme is experimented to establish the validity by extracting adequate multiple watermark data from the restructured cover image after applying common geometric transformation attacks (like rotation, cropping, scaling and deletion of lines/columns etc.), common enhancement technique attacks (like lowpass filtering, histogram equalization, sharpening, gamma correction, noise addition etc.) and JPEG compression attacks.     

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.     

Robust blind image watermarking using crisscross inter-block prediction in the DCT domain

Watermarking has been proposed as a solution to the problem protecting copyrighted multimedia in networked environments. This paper presents a simple but effective blind watermarking scheme capable of satisfying requirements pertaining to imperceptibility as well as robustness, while maintaining a sufficient payload capacity. In the proposed scheme, partly sign-altered mean modulation and mixed modulation are introduced to the crisscross discrete cosine transform (DCT)-based inter-block. Substituting a set of coefficients for a single coefficient enhances robustness against malign attacks. The inclusion of mixed modulation enables control over the parameters required to provide resistance against commonly encountered attacks while maintaining a high peak signal-to-noise ratio. Experiment results demonstrate that the proposed algorithm exceeds the performance of the seven other schemes in providing robust resistance to variety of attacks, particularly those associated with Gaussian noise and speckle noise.     

A blind color digital image watermarking method based on image correction and eigenvalue decomposition

With the rapid development of Internet technology, the copyright protection of color images has become more and more important. In order to fulfill this purpose, this paper designs a blind color digital image watermarking method based on image correction and eigenvalue decomposition (EVD). Firstly, all the eigenvalues of the pixel block in the color host image are obtained by EVD. Then, the sum of the absolute value of the eigenvalues is quantified by the variable quantization steps to embed the color watermark image that encrypted by affine transform and encoded by the Hamming code. If the watermarked image is processed by geometric attack, then the attacked image can be corrected by using the geometric attributes. Finally, the inverse embedding process is performed to extract the color watermark. Moreover, the advantages of the proposed method are shown as follows: (1) all Peak Signal-to-noise Ratio (PSNR) values are greater than 42 dB; (2) the average Structural Similarity Index Metric (SSIM) values are greater than 0.97; (3) the maximum embedded capacity is 0.25bpp; (4) whole running-time is less than 20 s; (5) the key space is more than 2⁴⁵⁰; (6) most Normalized Cross-correlation (NC) values are more than 0.9. Compared with the related methods, the experimental results show that the proposed method not only has better watermark invisibility and larger watermark capacity, but also has higher security and stronger robustness against geometric attacks.     

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。     

Local quaternion PHT based robust color image watermarking algorithm

It is a challenging work to design a robust localized color image watermarking scheme against desynchronization attacks. There are two main drawbacks indwelled in current localized color image watermarking: firstly, the pure gray-based feature points detectors were utilized, in which the important color information is ignored. Secondly, the watermarking algorithms were designed mainly to mark the image luminance component only, in which the significant color channels correlation are neglected. In this paper, we propose a robust color image watermarking algorithm using local quaternion PHT (Polar Harmonic Transform), which is invariant to various noises, local geometric transformations, and color variations. Firstly, the stable color image feature points are extracted by using new color image feature point detector, in which the SIFER (Scale-Invariant Feature detector with Error Resilience) detector and color invariance model are incorporated. Then, the affine invariant local regions are built adaptively according to local image content variation. Finally, the digital watermark is embedded into the local regions by modulating the invariant quaternion PHT modulus coefficients. Experiments are carried out on a color image set collected from Internet, and the extensive experimental works have shown that the proposed color image watermarking is not only invisible and robust against common image processing operations such as median filtering, noise adding, and JPEG compression, but also has conquered those challenging desynchronization attacks.     

基于小波变换的彩色图像数字水印新算法

提出了一种将灰度图像嵌入到原始彩色图像中的新数字水印算法.对RGB色彩空间彩色图像的绿色分量和蓝色分量进行haar小波变换.低频系数经过量化,将经过Arnold置乱后的灰度水印图像的位平面嵌入到低频子带.水印提取不需要原始载体图像.实验结果表明,该彩色图像数字水印算法不仅具有较好的透明性,而且对诸如叠加噪声、JPEG压缩、平滑滤波、几何剪切、图像增强和马赛克效果等攻击均具有较好的鲁棒性.     

A novel blind robust image watermarking in DCT domain using inter-block coefficient correlation

This paper presents a novel blind watermarking algorithm in DCT domain using the correlation between two DCT coefficients of adjacent blocks in the same position. One DCT coefficient of each block is modified to bring the difference from the adjacent block coefficient in a specified range. The value used to modify the coefficient is obtained by finding difference between DC and median of a few low frequency AC coefficients and the result is normalized by DC coefficient. The proposed watermarking algorithm is tested for different attacks. It shows very good robustness under JPEG image compression as compared to existing one and also good quality of watermark is extracted by performing other common image processing operations like cropping, rotation, brightening, sharpening, contrast enhancement etc.     

基于非抽样小波变换的彩色图像水印算法

图像水印技术已成为维护版权、抵制盗版和非法复制的重要手段,本文提出一种基于非抽样小波变换的彩色图像水印算法。非抽样小波变换不需进行下抽样操作,可获得与源信号同等长度的分解结果,具有信息冗余性和平移不变性的特点,提高了水印算法的鲁棒性和水印嵌入容量,算法同时结合奇异值分解,实现水印鲁棒性、不可见性和容量的统一。实验表明,该算法相对于基于离散小波变换的图像水印算法,能更好地抵抗噪声、压缩、剪切、旋转、平移等攻击。     

基于子采样方法的DCT域盲水印技术

提出了一种增强水印鲁棒性的盲水印算法.算法在DCT(离散余弦变换)变换域,采用子采样的方法,选择嵌入水印的位置;以视觉感知模型调节嵌入水印的强度.算法的提取不需要原始图像,实现了盲提取.实验结果表明,算法不仅具有较好的不可见性,水印信息在噪声干扰、滤波、图像压缩等攻击下具有较好的鲁棒性.     

基于DCT的自适应多重彩色图像盲水印算法

针对现有图像水印算法的一些不足,提出了一种基于离散余弦变换的自适应多重彩色图像盲水印算法。该算法根据彩色载体图像内容特点,将预处理后的不同二值图像水印自适应地嵌入到其绿色分量的离散余弦变换低频系数和中频系数,实现了不同水印在彩色载体图像中的嵌入及盲提取。实验结果表明,该算法在保证不可觉察性的前提下能够较好地抵抗各类常规攻击,具有良好的稳健性。     

基于DCT变换的QWT域改进的图像盲水印算法

针对数字图像的版权保护,基于离散余弦变换和四元数小波变换,提出了一种新的改进的盲水印算法,先根据待嵌入水印的大小对载体图像进行四元数小波变换,获得与幅值和相位信息相对应的4幅低频子带,然后对每个低频子带分别进行全局离散余弦变换,最后通过修改两个随机子带中特定位置上DCT系数的大小关系嵌入水印,利用分阶线性Logistic映射产生的混沌序列预处理经Arnold置乱后的水印信息和确定水印的嵌入位置.实验结果表明,该算法对添加噪声、JPEG压缩、滤波和亮度及对比度调整等攻击都具有很强的鲁棒性.     

基于关键熵的双树复小波域盲图像水印算法

设计了一种基于关键熵的盲数字图像水印算法.首先,使用尺度不变特征变换(SIFT)方法,从图像中提取特征点;其次,以特征点为中心构造局部不变圆形区域,并对其进行归一化处理;然后,选取大于图像平均熵的图像区域作为关键熵图像区域;最后,结合量化调制策略及双树复小波变换(DTCWT)技术,将水印嵌入到关键熵图像区域中.实验分析...     

DCT域迭代混合的数字图像水印

提出了基于离散余弦变换和迭代混合的图像水印算法。选取图像DCT域的中频系数,对其运用迭代混合技术嵌入水印,用新的DCT系数置换原来位置的DCT系数。本系统主要包括水印的嵌入、水印的提取和水印的攻击实验三部分,其中水印图像的攻击试验又包括三种攻击试验:椒盐噪声干扰、滤波和剪切攻击,利用这三种攻击来测试水印算法的性能。仿真实验结果表明,该水印算法对于噪声干扰、滤波和剪切攻击都具有较好的鲁棒性,也是图像迭代混合思想成功应用于数字水印方面的一个例子。     

基于视觉特性和小波分解的数字水印隐藏方法

本文提出了一种隐藏数字水印的新方法,该方法所隐藏的不是传统的序列码或比特流,而是将水印作为一幅二值图像来处理;并结合人眼视觉模型（ＨＶＳ）和图像的ＤＷＴ多尺度分解来隐藏水印。实验表明这种新方法在降低原始图像变换后视觉失真和提取的被隐藏水印图像失真两方面都达到较好的效果,鲁棒性也较好,这是一种很有发展前景的数字水印隐藏新方法。     

一种多传感器图像融合与数字水印技术

在小波包域提出了一种多传感器图像融合和双水印算法。首先,利用HIS变换和小波包变换将多光谱和全色图像分解为多个高低频子带,根据小波包域系数特点,低频部分采用基于区域平均能量加权算法的规则进行融合,高频部分采用绝对值取大的规则进行融合。然后,在高低频图像融合系数分别嵌入一个水印,低频水印利用了离散余弦变换的聚能去相关能力,高频水印利用了图像纹理子块特征。最后,对嵌入的双水印融合图像进行攻击和分析。实验结果显示,融合图像在保留多光谱图像光谱信息的基础上有效提高了空间分辨率;加水印的融合图像具有良好的不可视性和鲁棒性。     

灰度共生矩阵纹理特征选块的可逆图像水印

针对当前灰度共生矩阵(GLCM)的4个主要特 征参数与图像子块纹理复杂度之间没有准确的数学关系和隐蔽 图像遮蔽性上不足的问题,提出一种GLCM纹理特征选块的可逆图像水印。首先把原宿主 图像分成 128×128大小的子块;然后利用均方误差(MSE)给 4个纹理特征参数赋予权值,建立特征参数与图像子块复杂度 的数学关系;最后计算得出各个子块的复杂度,选择复杂度最大和次大的子块,采用基于预 测误差对扩展 的可逆算法进行数据隐藏。提出的特征参数与纹理复杂度之间的数学关系,能够准确计算图 像子块复杂度, 嵌入水印后的自然图像和医学图像平均峰值信噪比(PSNR)值较 现有方法分别高出2.65%和0.93%左右。本文算 法能准 确反映子块内部的纹理复杂度并具有更好的隐蔽性,适用于医学、军事和卫星等领域。     

一种解决版权问题的数字水印方案

大部分水印技术侧重于水印的不可见性和稳健性,而版权保护问题并未得到真正解决。该文提出的数字水印方案可以有效地解决这一问题。通过一种新颖的水印构造方法,有效地消除了在解决版权问题中对使用原始图像的限制。盲与非盲水印检测时水印的不可见性和稳健性均得到很大提高。实验结果证明该数字水印方案对于版权攻击是有效的,对各种失真都具有较强的稳健性。     

一种基于小波变换的盲水印算法

提出了一种基于小波变换的盲水印算法，根据各个层次相应位置的小波系数排序情况和密钥中{1}元素的位置来决定水印嵌入的位置，在水印提取时根据密钥中{1}的位置可以实现盲水印提取，实验证明具有较好的效果。     

用于CMOS图像传感器芯片的多功能盲水印算法

提出了一种在小波域中同时嵌入鲁棒水印和脆弱水印的算法。根据相邻小波系数间的关系在JPEG压缩后大多不发生变化的事实,首先对原始载体图像进行一级小波分解,然后将鲁棒水印嵌入到小波的低频系数LL中,脆弱水印嵌入到小波的高频子带HL中,水印提取和图像认证均不需要原始图像参与,很好实现了水印的盲检测。实验结果表明:本文算法对常见的非恶意攻击提取的鲁棒水印和半脆弱水印的归一化相关系数(NC)值几乎都在0.8以上;对恶意的图像操作可以精确检测和定位;算法嵌入容量大,抗JPEG压缩性能高和计算简单,可以集成于CMOS图像传感器芯片中。