基于整型小波变换的彩色图像盲水印算法*

针对多数图像水印算法将灰度图像嵌入宿主图像的研究现状,提出了一种基于整型小波变换将彩色数字水印嵌入到彩色宿主图像中的算法。本算法结合人眼的视觉掩蔽特性, 实现了数字水印嵌入位置的自适应确定,同时采用量化小波系数的方法将彩色水印嵌入到彩色图像YCrCb模式的Y分量中去,彩色水印的提取不需要原始水印和原始宿主图像。实验证明,水印具有良好的不可见性,并且对常见的图像处理操作具有很强的鲁棒性。     

基于YIQ色彩空间的彩色图像盲水印算法*

提出了一种将彩色图像作为数字水印嵌入到彩色宿主图像中的新算法,用于图像版权保护。将彩色水印图像进行一维数字化处理,并将彩色宿主图像由RGB色彩模式转换成YIQ色彩模式,采用整数小波变换将彩色水印嵌入到彩色图像YIQ色彩空间的Y分量中。彩色水印的提取不需要原始水印和原始宿主图像。实验表明：该数字水印算法不仅具有良好的透明性,而且对诸如叠加噪声、JPEG压缩、几何剪切、平滑滤波等攻击具有很强的鲁棒性。     

A blind double color image watermarking algorithm based on QR decomposition

In this paper, a novel blind image watermarking scheme based on QR decomposition is proposed to embed color watermark image into color host image, which is significantly different from using the binary or gray image as watermark. When embedding watermark, the 24-bits color host image with size of 512?×?512 is divided into non-overlapping 4?×?4 pixel blocks and each pixel block is decomposed by QR. Then, according to the watermark information and the relation between the second row first column coefficient and the third row first column coefficient in the unitary matrix Q, the 24-bits color watermark image with size of 32?×?32 is embedded into the color host image. In addition, the new element compensatory method is used in the upper-triangle matrix R for reducing the visible distortion. When extracting watermark, only the watermarked image is needed. Compared with other SVD-based methods, the proposed method does not have the false-positive detection problem and has lower computational complexity, that is, the average running time of the proposed method only needs 1.481403 s. The experimental results show that the proposed method is robust against most common attacks including JPEG compression, JPEG 2000 compression, low-pass filtering, cropping, adding noise, blurring, rotation, scaling and sharpening et al. Compared with some related existing methods, the proposed algorithm has stronger robustness and better invisibility.     

基于IWT和HVS的彩色图像盲水印算法

针对目前大多数图像水印技术是关于灰度图像并且基于离散小波变换的研究,提出了一种基于整型小波变换（Integer Wavelet Transform,IWT）将彩色数字水印嵌入到彩色宿主图像中的算法。采用YCbCr色彩空间的Y分量嵌入水印,利用人类视觉系统特性（Human Visual System,HVS）实现彩色水印嵌入位置的自适应确定;彩色水印的提取不需要原始水印和原始宿主图像。实验证明,嵌入水印后的图像具有很好的不易觉察性,并且对常见的图像处理操作具有很强的鲁棒性。     

Fractal and neural networks based watermark identification

Transform techniques generally are more robust than spatial techniques for watermark embedding. In this paper, a color image watermarking algorithm based on fractal and neural networks in Discrete Cosine Transform (DCT) domain is proposed. We apply fractal image coding technique to obtain the characteristic data of a gray-level image watermark signal and encrypt the characteristic data by a symmetric encryption before they are embedded. We then use neural networks and Human Visual System (HVS) to embed the watermark in the DCT domain. A Just Noticeable Difference (JND) threshold controller is designed to ensure the strength of the embedded data adapting to the host image itself entirely. Aiming at misjudging problem of the extracting process, maximum membership principle criterion is selected for identifying the watermark. And the CIELab color space is chosen to guarantee the stability of the results. The simulation results show that the algorithm is robust for common digital image processing methods as attacks and that the quality of the image is retained.     

基于DCT的彩色图像数字水印算法

实现一种在彩色载体图像中嵌入彩色水印图像的算法。在嵌入时,先将载体图像分成与水印图像大小相同的块;然后,在DCT变换域中,将水印图像R、G、B层的变换系数嵌入到载体图像每一块对应层的中低频系数中。在提取时,先通过DCT反变换从带水印图像的每一块中提取出水印图像,再计算这些水印图像的平均值从而得到最终的水印图像。测试结果表明该算法满足了数字水印的不可见性和鲁棒性要求。     

彩色数字图像的脆弱数字水印

针对彩色数字图像局部区域内容保护和认证,研究了彩色数字图像的脆弱数字水印.为了保证水印的安全性,利用三维二值混沌序列对原始二值水印图像进行加密,对提取的加密二值水印图像进行解密.嵌入载体图像的水印和从嵌入水印的图像中提取的水印均是加密水印.将彩色数字图像中被保护区域的三个分量的小波变换域分别嵌入加密水印,以保护其内容的完整性和不可篡改性.采用模运算实现水印的嵌入和盲提取.理论分析和实验结果表明,该脆弱水印算法对彩色数字图像保护区域内的任何篡改,都能够正确地检测和定位.     

基于块均值调制的彩色图像公开水印技术

为了解决彩色图像的水印嵌入、空间域水印的低稳健性和公开水印的设计等问题,提出一种新的空间域公开水印技术。该技术将水印嵌入到视觉不太敏感的蓝色通道中,通过调制图像子块均值在映射区间上的分布,构建新的图像稳定特征,并实现水印的嵌入和盲检测。讨论了调制区间的最大精度以及映射区间长度对算法稳健性的影响。实验结果表明本方法对多种图像处理具有稳健性。     

基于小波变换的图像自适应公开水印技术

提出了一种鲁棒的基于分块离散小波变换（DWT）的图像自适应公开水印技术。在充分考虑HVS掩蔽特性的基础上,利用不同分解层次小波系数块相关的特点,通过修改相应小波系数块之间的关系,自适应地嵌入水印信号。在提取水印时,不需要原始图像,完全实现了盲水印提取。通过修改自定义的参数,可以在水印透明性与鲁棒性之间找到最佳取舍点。实验结果表明,该算法具有较大的容量,对通常的图像处理操作和几何攻击等都具有较强的鲁棒性。     

A new watermarking scheme for colour image using QR decomposition and ternary coding

At present, the binary images are often used as the original watermark images of many watermarking methods, but partial methods cannot be easily extended to colour image watermarking methods. For resolving this problem, we propose a new watermarking method using ternary coding and QR decomposition for colour image. In the procedure of embedding watermark, the colour image watermark is coded to ternary information; the colour host image is also separated into image blocks of sized 3?×?3, and these image blocks are further decomposed via QR decomposition; then, one ternary watermark is embedded into one orthogonal matrix Q of QR decomposition by the proposed rules. In the procedure of extracting watermark, the proposed method uses the blind-manner to extract the embedded ternary information. The novelty of this scheme lies in the proposed ternary coding for watermark image, which can improve the imperceptibility, embedded watermark capacity and real-time feature of the watermarking scheme. The results of simulation show the presented technique is better than other compared schemes with respect to imperceptibility, embedded watermark capacity and real-time feature under the similar robustness.

     

基于离散余弦变换彩色图像的数字水印研究

为了在彩色图像中嵌入彩色数字水印,同时保持原始彩色图像的完整性及健壮性,提出基于空间域和频率域间转换,配合RGB色彩系统,利用离散余弦变换将图像的空间域表示转换为频率域,将彩色数字水印频域系数经适当处理后嵌入图像的低频部分,使嵌入的彩色数字水印能抵抗各种图像处理时的破坏.实验结果表明:应用该方法嵌入彩色数字水印,不仅不破坏原始彩色图像品质,而且能抵抗外界的破坏,成功取回所嵌信息.     

整数小波变换的数字水印技术

提出一种基于整数小波变换的数字水印技术,以二值图像作为水印信息,为了增强水印的鲁棒性,嵌入时对原图像进行分块,提取水印时对提取出的水印进行数学形态学中的腐蚀和膨胀运算,提高了提取出的水印的辨识度。     

Using dynamic pixel value mapping method to construct visible and reversible image watermarking scheme

A reversible and visible image watermarking scheme extracts a visibly embedded binary watermark image and recovers the original cover image. This paper presents a reversible and visible image watermarking scheme that embeds visible watermarks into a part of the cover image, called the embedded region R, and embeds required binary strings into the whole image through the conventional difference-expansion method. The size of the embedded visible watermark is determined by the coefficient k; a large k value leads to a large embedded region for the visible watermark. The embedded region R is first segmented to non-overlapped k×k blocks, and each block is related to one bit of the watermark image. For those blocks that are related to the logo bits of the watermark image, these k×k blocks are adjusted by the proposed dynamic pixel value mapping method for highly visual detection. The binary bit string S, composed of the binary watermark image and LSB bits of the logo watermark bits’ corresponding k×k blocks, is embedded into the cover image using the conventional difference-expansion method. Experimental results show that the watermark is clearly embedded into the embedded region R and that the distortion of the reversible embedding is limited.     

基于神经网络的自适应彩色图像盲水印算法

文中提出的算法是自适应地将水印嵌入,并利用神经网络实现水印的盲提取。首先将二值水印嵌入到YIQ色彩空间的Y分量小波分解的低频系数中,为达到平衡水印图像的鲁棒性和不可见性,嵌入的强度是根据人类视觉特性自适应调整至最佳;利用BP神经网络的学习和自适应的特性和一段已知序列训练神经网络,可实现水印的盲提取;在神经网络的输入信号计算上提出选择邻域窗口为3*3方形窗口比十字窗口具有更好的实验效果。仿真实验结果表明该算法对常用的图像处理具有较好的鲁棒性和不可见性。     

基于DWT-SVD域的彩色图像自适应水印算法

为了保护数字彩色图像版权,提出了一种结合离散小波变换(DWT)和矩阵奇异值分解(SVD)的彩色图像自适应水印算法。其主要设计思想是:先将原RGB彩色图像的各颜色分量进行小波分解;再将得到的中、低频带的小波系数与原水印图像分别进行奇异值分解,水印信息的奇异值重复嵌入到三通道中、低频带的小波系数奇异值中,且利用临界视觉阈值与奇异值之间的关系对水印嵌入强度作自适应调节,从而达到增强水印鲁棒性和确保水印透明性的目的。本算法适用于二值及灰度水印,在二值水印的提取过程中需设定一个提取阈值,以保证提取水印的完整性。仿真结果说明本算法对水印系统的透明性与鲁棒性作了较好的协调,是一种较稳健的算法。     

基于多位平面嵌入的二元纯位相滤波器水印

二元纯位相滤波器（BPOF）数字水印是一种用于图像真实性认证的半脆弱水印技术。它由图像离散Fourier变换（DFT）的幅值和相位分别得到幅值位平面和BPOF,并将BPOF作为水印嵌入到幅值位平面中。本文〖BP）〗在简要分析基于单一幅值位平面嵌入BPOF水印的基础上,讨论了使用多个幅值位平面嵌入水印并进行了性能分析。通过仿真实验得到了优化方案：以多个幅值位平面嵌入水印,而从其中的最高位平面中提取水印可以明显提高水印性能。     

基于平衡多小波的改进的盲水印算法

利用图像经过CARDBAL平衡多小波变换(BMWT)后,能量汇聚且平均分摊在最低分辨率子图像4个分量上的特点,提出了一种基于BMWT和DCT的改进的盲水印算法.在彩色图像的饱和度分量上嵌入一幅二值水印图像,水印嵌入前进行Arnold置乱和混沌加密预处理,保证了算法的安全性.实验结果表明,改进后的算法具有良好的鲁棒性,而且在抵抗JPEG压缩性能方面有明显的提高.     

一种DCT变换域的鲁棒数字水印

提出一种以二值图像为水印的离散余弦变换(DCT)域数字水印算法,对水印图像进行Arnold置乱,用置乱次数作为提取时的密钥,将置乱后的水印图像和载体图像分别进行分块DCT。为了使嵌入的水印具有较强的鲁棒性,把水印的每个子块同时嵌入到多个载体图像的子块中,按照奇数块和偶数块分别将水印嵌入到直流分量和交流分量的中频系数中,实现水印的完全嵌入。实验结果证明,该算法具有良好的鲁棒性和不可见性,能够抵抗有损压缩、剪切、随机涂改和白噪声等攻击。     

基于人眼视觉系统的自适应量化数字水印算法研究

提出了一种将彩色水印图像嵌入到原始彩色功载体图像中的新算法。首先，利用DCT静态图像压缩技术，将彩色水印图像编码成一维二进制序列并进行随机置乱；然后将原始彩色载体图像分解为R、G、B三个彩色分量并分别实施小波变换，进而结合视觉感知特性自适应确定水印嵌入位置；最后结合人眼视觉系统（掩蔽特性及对颜色的感知特性）确定量化间隔，并通过全新的量化处理过程完成水印信息的白适应嵌入，仿真实验表明：该数字水印嵌入方案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、马赛克效果等攻击均具有较好的鲁棒性．     

A simple and efficient watermark technique based on JPEG2000 Codec

In this paper we propose an effective watermark scheme for embedding and extracting based on the JPEG2000 Codec process. Our embedding algorithm applies the torus automorphisms (TA) technique to break up and scramble a watermark. The scrambled watermark was embedded into the quantized bitstreams of JPEG2000 before the entropy coding stage. Distortion reduction (DR) was applied to the compressed image to lessen image degradation caused by the embedding process. Our watermark scheme is simple and easy to implement. Furthermore, it is robust to attacks like blurring, edge enhancement, and other image processing manipulations.Corespondence to: J. Chen (P.O. Box 63-146, Taichung, Taiwan 406, R.O.C.)