基于图象特征的小波域水印算法

提出一种基于图象特征点的小波变换域第二代水印算法.首先对图象作小波变换,其中最低频成分是图象的粗尺度(低分辨率)逼近,从中提取出图象的特征点;然后在特征点对应的所有高频系数中嵌入水印.水印检验不需要原始图象,但需要原始图象的特征点位置信息,计算特征点对应的所有高频系数与嵌入水印的互相关,利用门限值检验水印是否存在. 实验证明该算法对通常的图象处理有很强的鲁棒性,对有损压缩的鲁棒性尤为突出,而且对几何变换也有一定鲁棒性.     

基于心理声学模型和临界频带子波变换的数字声频水印

提出了一种基于临界频带子波变换的声频数字水印算法。首先根据心理声学模型,计算载体声频信号的掩蔽阈值,利用人耳听觉的临界频率与临界频带子波变换域的相似性,将掩蔽门限映射到临界频带子波域,然后将水印信号嵌入到中低频子波系数中,嵌入强度由掩蔽阂值自适应控制。实验结果表明:该算法隐藏水印具有很强的掩蔽性,对原始语音的影响基本上察觉不出来;叠加了水印的声频信号对数据压缩、加噪、重采样、低通滤波等常用声频信号处理技术具有很好的鲁棒性。     

一种自适应的盲水印方法

目前数字水印算法多局限于在图象中嵌入特定的标记,并通过改变空域值或频域系数值来达到目的.提出了一种新颖的自适应盲水印方法.首先基于小波变换的零树结构,找出重要系数,然后根据重要系数所在区域的特性构造出一个序列信息,再利用置乱变换最终得到水印信息,而不修改图象本身的任何特征.因此水印的不可见性从根本上得到了保证.其中,重要系数的选择是自适应于图象的,并且水印的检测是不需要原始图象的盲检测.实验证明该方法的鲁棒性较强,是一种行之有效的方法.     

分数傅里叶域数字水印算法

基于离散分数傅里叶变换(DFRFT)快速算法发展了一种分数傅里叶谱域图像水印算法.该算法根据分数傅里叶变换谱具有空域和频域双域信息表达能力,分别对原始图像和所加水印信息进行不同级次的分数傅里叶变换,提取水印分数傅里叶谱的低频成分并直接将其叠加到原始图像的分数傅里叶谱中的对角像元上,然后再进行逆变换得到水印图像.在JPEG压缩、图像旋转及剪切等攻击方式下,对该水印算法进行了鲁棒性分析,数值实验表明该水印算法具有良好的抗攻击性和安全性.     

基于混沌Logistic和Arnold二次加密的图像水印算法研究

针对图像水印在不可见性和鲁棒性方面很难同时满足的问题。提出一种基于混沌对原始水印图像进行双重加密的方法,使水印信息具有双重的保密性;根据人眼视觉系统将不同强度的水印分量自适应地嵌入到DCT的中频系数中,使嵌有水印的图像具有良好的视觉不可见性。实验表明,该算法在水印自身的安全性和相关性,系统的鲁棒性方面相对于其它算法都有很大的提高。     

基于SIFT图像特征区域的全息水印技术

为了增强水印的不可见性和鲁棒性,提出了一种基于图像特征区域的水印算法。首先利用SIFT(Scale Invariant Feature Transform)算法从载体图像蓝色B通道中提取图像特征点来进行优化和筛选,根据优化后的稳定特征点及其特征尺度确定图像的特征区域,再结合全息技术,对原始水印图像进行双随机相位加密,生成加密全息水印;然后对特征区域进行离散余弦变换(DCT);最后在其中频区域嵌入加密全息水印。在提取水印时无须借助原始图像,是盲水印技术。实验结果表明:该算法重建的水印图像与原始水印图像的NC值高达0.95;水印的嵌入对图像质量影响很小,PSNR值高达55.97,能够抵抗常规信号攻击及缩放、剪切、平移等几何攻击。     

基于混沌的自嵌入安全水印算法

利用混沌系统的伪随机性和初值敏感性，提出一种基于混沌的自嵌入安全水印算法.该算法以混沌初值为密钥生成混沌序列，根据混沌序列的索引有序序列随机生成图像块的水印嵌入位置.与现有的自嵌入算法相比，该算法实现了水印嵌入位置的随机选取，有效扩大了算法的密钥空间，且解决了自嵌入水印算法如何准确定位篡改块的问题.理论分析和仿真结果表明，该算法不仅提高了自嵌入水印算法的篡改定位的能力，而且进一步增强了算法抵抗向量量化攻击和同步伪造攻击的能力. 关键词： 数字水印 混沌 脆弱水印 自嵌入     

基于虚拟通道技术的数字图像灰度水印算法

根据提出的虚拟通道技术,提出一种在载体中嵌入灰度图像作为水印的数字水印算法.通过修改载体频率域系数,载体通道可被看成一个虚拟的水印通道,它由若干个缺损的水印子通道构成,水印的提取不需要原始载体或原始水印的参与.实验结果表明提出的算法很好地保证了水印的不可见性和稳健性.     

图象的多尺度边缘相位水印算法

提出一种基于图象多尺度边缘的新相位水印算法.利用常用于边缘检测的二进小波刻画图象的多尺度边缘,在多尺度边缘的相位成分中嵌入数字水印,利用相关检测器进行水印检测.实验证明算法具有不可见性,较好的安全性,对通常的图象处理有很强的鲁棒性.     

矢量图形中基于小波变换的盲水印算法

提出一种用于矢量图形的数字水印方法.该方法将矢量图形中图元的顶点坐标有顺序地排成一维序列,通过离散小波变换将序列分解成不同空间和频率上的复值系数,并根据水印的大小与小波系数之间的关系把水印嵌入到小波系数的幅值中,系数的相位不变.该算法在提取水印时不需要原始矢量图形.实验证明该算法具有良好的不可见性和较强的鲁棒性.     

基于二值化计算鬼成像的盲水印方法

提出了一种基于二值化计算鬼成像的盲水印方法.首先将水印图像经计算关联成像加密系统加密,并将加密数据二值化,然后将其隐藏到宿主图像的离散余弦变换域,实现水印信息的嵌入.水印信息的提取和重建是隐藏和加密的逆过程,分别借助提取密钥和解密密钥获取水印信息.仿真实验证明,该方法具有很好的隐蔽性,在嵌入因子α=10时,嵌入水印仍具有较好的不可感知性,含水印图像的峰值信噪比在38 dB以上;另外,该方法也具有一定的容错能力,提取的加密数据错误率达20%时,重建的水印信息仍能分辨和识别;与传统的计算鬼成像相比,加密数据的二值化为水印嵌入提供了方便,但是并未对重建图像带来严重恶化,其相关系数相差不足0.1;水印信息的提取无需借助原始宿主图像,是一种盲提取方法.     

A novel blind digital watermarking algorithm for embedding color image into color image

A robust and blind watermarking technique for dual color images is proposed in this paper. According to the energy concentrating feature of DCT, the two-level DCT is introduced and used to embed color watermark image into color host image, which is completely different with the traditional DCT. For reducing the redundancy of watermark information, the original color watermark image is compressed by the proposed compression method. After two-level DCT, nine AC coefficients in different positions of each sub-block are selected and quantified to embed watermark information. Moreover, only the extraction rules are used to extract watermark from the watermarked image without resorting to the original host image or watermark image. Experimental results show that the proposed watermarking algorithm can effectively improve the quality of the watermarked image and the robustness of the embedded watermark against various attacks.     

A blind color image watermarking based on DC component in the spatial domain

Color image watermarking has become essential and important copyright protection or authentication scheme. It is noted that most of the existing color image watermarking algorithms are performed only in the single domain (spatial domain or frequency domain), and not to integrate these merits of the different domains. By utilizing the generating principle and distribution feature of the direct current (DC) coefficient, a novel blind watermarking algorithm is proposed for color host images in this paper. Firstly, the Y luminance of host image is divided into 8 × 8 sub-blocks and the DC coefficients of each block are directly calculated in the spatial domain without DCT transform. Secondly, according to the watermark information and the quantization step, the DC coefficients are calculated and their increments are further utilized to modify directly the values of all pixels in the spatial domain instead of the DCT domain to embed watermark. When watermark extraction, only the watermarked image and the quantization step are needed in the spatial domain. Experimental results show that the proposed method not only can resist both traditional signal processing attacks and geometric attacks, but also has more efficient in computational complexity. Comparisons also demonstrate the advantages of the method.     

基于级联分数傅里叶变换系统的数字水印技术

提出一种基于分数傅里叶变换和随机相位编码的光学加密数字水印技术,可成为一种信息隐藏及保护的有效方案.该数字水印技术对于噪音叠加和常见的图像处理操作具有较强的稳健性.该技术根据光学级联分数傅里叶变换系统,利用两个随机相位分布函数对水印信息编码并经过迭代分数傅里叶变换嵌入到变换域的载体图像中.在水印检测和提取过程中,两个相位分布函数作为密钥.随机相位编码技术的引入,进一步提高了数字水印系统的密钥空间.增强了系统的安全性.该数字水印技术基于光学分数傅里叶变换原理,可以利用光学变换系统方便地实现.     

Optical 3D watermark based digital image watermarking for telemedicine

Region of interest (ROI) of a medical image is an area including important diagnostic information and must be stored without any distortion. This algorithm for application of watermarking technique for non-ROI of the medical image preserving ROI. The paper presents a 3D watermark based medical image watermarking scheme. In this paper, a 3D watermark object is first decomposed into 2D elemental image array (EIA) by a lenslet array, and then the 2D elemental image array data is embedded into the host image. The watermark extraction process is an inverse process of embedding. The extracted EIA through the computational integral imaging reconstruction (CIIR) technique, the 3D watermark can be reconstructed. Because the EIA is composed of a number of elemental images possesses their own perspectives of a 3D watermark object. Even though the embedded watermark data badly damaged, the 3D virtual watermark can be successfully reconstructed. Furthermore, using CAT with various rule number parameters, it is possible to get many channels for embedding. So our method can recover the weak point having only one transform plane in traditional watermarking methods. The effectiveness of the proposed watermarking scheme is demonstrated with the aid of experimental results.     

A blind dual color images watermarking based on IWT and state coding

In this paper, a state-coding based blind watermarking algorithm is proposed to embed color image watermark to color host image. The technique of state coding, which makes the state code of data set be equal to the hiding watermark information, is introduced in this paper. When embedding watermark, using Integer Wavelet Transform (IWT) and the rules of state coding, these components, R, G and B, of color image watermark are embedded to these components, Y, Cr and Cb, of color host image. Moreover, the rules of state coding are also used to extract watermark from the watermarked image without resorting to the original watermark or original host image. Experimental results show that the proposed watermarking algorithm cannot only meet the demand on invisibility and robustness of the watermark, but also have well performance compared with other proposed methods considered in this work.     

基于HVS的小波变换数字图像水印算法

为实现图像水印在数据认证、访问控制和版权保护等领域发挥作用,提出一种人眼视觉感知特性的小波变换数字图像水印算法。首先对二值图像水印进行Arnold变换,并采用行堆叠的方法,转换成一维序列,然后根据密钥生成的高斯序列中值的正负来确定水印信息嵌入时是采用那种调制方式,最后对原始图像进行3级DWT分解,在小波图像的第二层中频子带中,结合人眼视觉特性将水印正向或负向调制叠加在宿主图像大于JND 值的小波系数上。实验结果表明:该算法能抵抗JPEG压缩、加噪、剪切等多种攻击,具有良好的透明性,鲁棒性和安全性。     

Blind image watermarking based on discrete fractional random transform and subsampling

This paper proposes a blind watermarking scheme based on discrete fractional random transform. The watermark information can be a binary sequence, a gray level image or a set of decimal fractions sampled from a given source signal. The host image is subsampled into four subimages, and the high correlations among their discrete fractional random transform coefficients are exploited for watermark embedding. Based on this self-reference strategy, the watermark can be extracted without the aid of the host image. As a fragile watermarking technique, our scheme can be used in tamper detection. Besides, it can be used in self-embedding for a large payload is provided. Meanwhile, security of the watermark is preserved due to the randomness of the discrete fractional random transform. Experimental results demonstrate the effectiveness of our scheme.