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。     

一种空频域结合的自适应二值图像水印算法

本文提出了一种向二值图像中嵌入水印的算法。首先对原始二值图像做小波变换，通过分析其小波系数来寻找图像纹理及细节较丰富的区域，作为水印嵌入域。然后在空域中通过改变嵌入点的像素值来嵌入水印。根据图像的纹理丰富程度来自适应地选取嵌入水印的长度。实验结果表明，该算法具有较强的不可见性和鲁棒性，是一种有效的二值图像的水印嵌入算法。     

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。     

一种基于小波分析的自适应图像水印算法

提出一种在小波变换域自适应嵌入数字水印的算法。由人眼视觉系统特性，在第三级小波系数子图中嵌入水印信号。水印强度与图像的显著性成正比，使水印对原图像具有自适应性。对水印图像进行各种退化处理的实验表明，提出的数字水印算法具有很好的鲁棒性。     

一种基于图像内容的小波域半脆弱水印算法

在充分考虑图像视觉屏蔽特性的基础上,提出一种小波域图像半脆弱水印算法.嵌入水印基于小波低频子带系数产生,该方案通过自适应地修改小波变换后水平与垂直细节子带系数以嵌入水印,嵌入水印具有较好的透明性.实验结果证明了算法对非恶意攻击的鲁棒性和对恶意攻击的脆弱性.     

一种基于小波分析的自适应图像水印算法

提出一种在小波变换域自适应嵌入数字水印的算法。由人眼视觉系统特性,在第三级小波系数子图中 嵌入水印信号。水印强度与图像的显著性成正比,使水印对原图像具有自适应性。对水印图像进行各种退化处理的 实验表明,提出的数字水印算法具有很好的鲁棒性。     

图像小波变换低频域的水印嵌入与检测算法

数字水印是数字媒体版权保护的有效手段。文章详细分析了小波域图像水印嵌入策略，提出一种小波域透明图像水印算法，算法选择图像经过小波多分辨率分解后的低频子带作为水印嵌入区域，并利用人眼视觉掩蔽特性对水印的添加强度进行自适应调节。实验获得了良好的结果。     

一种基于小波域图像纹理特征的数字水印技术

提出一种基于小波域图像纹理特征的彩色图像盲水印算法。该算法根据。图像小波变换后小波系数的特点选择视觉重要系数，量化嵌入二值水印序列。利用人类视觉系统的纹理掩蔽特性和照度掩蔽特性自适应调整量化间距，以保证水印的透明性。算法实现了水印的盲检测。仿真实验的结果表明，算法对各种常用的水印攻击方法具有较好的鲁棒性。     

基于小波域的可见水印处理

本文提出一种小波域的自适应可见水印处理算法,该算法通过特殊设计的视觉模型,根据主图像和水印图像的特征,逐点确定水印嵌入的拉伸系数,从而使水印的嵌入程度依主图像和水印图像的特征变化而变化.实验表明,结果图像中的水印半透明地呈见在所覆盖的主图像区域,很好地保持了原始图像的细节,满足了对可见水印的一般性要求.     

Multiscale fragile watermarking based on the Gaussian mixture model.

In this paper, a new multiscale fragile watermarking scheme based on the Gaussian mixture model (GMM) is presented. First, a GMM is developed to describe the statistical characteristics of images in the wavelet domain and an expectation-maximization algorithm is employed to identify GMM model parameters. With wavelet multiscale subspaces being divided into watermarking blocks, the GMM model parameters of different watermarking blocks are adjusted to form certain relationships, which are employed for the presented new fragile watermarking scheme for authentication. An optimal watermark embedding method is developed to achieve minimum watermarking distortion. A secret embedding key is designed to securely embed the fragile watermarks so that the new method is robust to counterfeiting, even when the malicious attackers are fully aware of the watermark embedding algorithm. It is shown that the presented new method can securely embed a message bit stream, such as personal signatures or copyright logos, into a host image as fragile watermarks. Compared with conventional fragile watermark techniques, this new statistical model based method modifies only a small amount of image data such that the distortion on the host image is imperceptible. Meanwhile, with the embedded message bits spreading over the entire image area through the statistical model, the new method can detect and localize image tampering. Besides, the new multiscale implementation of fragile watermarks based on the presented method can help distinguish some normal image operations such as JPEG compression from malicious image attacks and, thus, can be used for semi-fragile watermarking.     

A Study of Steganographic Image Security

In this dissertation, sereral key problems in the field of steganographic image security are mainly studied and discussed: (1) A novel kind of image cryptosystem is studied. The encrypted information of secret image is embedded into an ordinary image, which can be transmitted publicly, and it will not cause attention of illegal eavesdropper. The following results are achieved: (a) The image hiding algorithm and its improved algorithm based on wavelet transform and vector quantization are propo…     

Quantisation-based video watermarking in the wavelet domain with spatial and temporal redundancy

In this article we introduce a new public digital watermarking technique for video copyright protection working in the discrete wavelet transform domain. The scheme uses binary images as watermarks. These are embedded in the detail wavelet coefficients of the middle wavelet sub-bands. The method is a combination of spread spectrum and quantisation-based watermarking. Every bit of the watermark is spread over a number of wavelet coefficients with the use of a secret key. The resilience of the watermarking algorithm was tested against a series of eight different attacks using different videos. To improve the resilience of the algorithm we use error correction codes and embed the watermark with spatial and temporal redundancy. The proposed method achieves a very good perceptual quality with mean peak signal-to-noise ratio values of the watermarked videos of more than 40 dB and high resistance to a large spectrum of attacks.     

一种基于HVS的图像易碎水印

作为多媒体认证和篡改检测的一种新技术,易碎水印正得到越来越多的关注.基于小波变换,结合量化调制过程,本文提出了一个易碎水印算法.该算法具有以下特点:(1)构造水印金字塔,便于实现水印的多分辨率检测;(2)结合视觉特性量化调制,尽可能减小视觉失真;(3)结合图像融合技术的多分辨率检测,使检测结果更准确;(4)抵抗一定程度的JPEG有损压缩.为了实现篡改的检测,本文给出了一个攻击判别方案,以区分恶意攻击和偶然攻击.实验表明,嵌入的水印在脆弱性和鲁棒性上达到了较好的统一,能够抵抗一定程度的压缩而不影响篡改检测的精确性.     

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。     

Gray-scale image watermarking using GA-BPN hybrid network

In this paper, a novel watermarking scheme is proposed by embedding a binary watermark into gray-scale images using a hybrid GA-BPN intelligent network. HVS characteristics of the images in DCT domain are used to obtain a sequence of weighting factor from a GA-BPN. This weighting factor is used to embed and extract the watermark from the image in DWT domain. The GA-BPN is trained by 27 inference rules that includes three input HVS parameters namely luminance sensitivity, edge sensitivity computed using threshold and contrast sensitivity computed using variance. The robustness of the embedding scheme is examined by executing seven different image processing attacks. Visual quality of signed images before and after the attacks is examined by PSNR. The extracted watermarks from signed and attacked images show a high degree of similarity with the embedded content. Overall, the algorithm is robust against selected attacks and is well optimized.     

Image watermarking using Hadamard transforms

A novel method based on the multi-resolution transform and complex Hadamard transform to embed watermarks in grey scale digital images is proposed. The results show that the presented scheme is robust to JPEG compression, image resizing cropping, dithering distortion and successive watermarking effects     

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     

基于分形技术的小波包域多重数字水印算法

文中提出了一种基于分形图像编码的方法,显著地减少了灰度图像水印嵌入的数据量,同时结合人类视觉系统模型,将混合多重水印嵌入到小波包域的多个频带内.使用对称加密算法的密钥作为个人密钥,水印方案具有双重的安全性.实验结果表明,该算法有效地克服了灰度图像水印数据量大的缺点,并且提高了水印的鲁棒性.大量仿真结果证明了该算法的有效性.     

Wavelet-based watermarking for color images through visual masking

In this paper, a wavelet-based watermarking scheme for color images is proposed. The watermarking scheme is based on the design of a color visual model that is the modification of a perceptual model used in the image coding of gray scale images. The model is to estimate the noise detection threshold of each wavelet coefficient in luminance and chrominance components of color images in order to satisfy transparency and robustness required by the color image watermarking technique. The noise detection thresholds of coefficients in each color component are derived in a locally adaptive fashion based on the wavelet decomposition, by which perceptually significant coefficients are selected and a perceptually lossless quantization matrix is constructed for embedding watermarks. Performance in terms of robustness and transparency is obtained by embedding the maximum strength watermark while maintaining the perceptually lossless quality of the watermarked color image. Simulation results show that the proposed scheme is more robust than the existing scheme while retaining the watermark transparency.