自适应于局部几何特征的三维模型水印算法

文章针对三维模型提出了一种稳健的三角网格数字水印算法,通过修改从模型中心到各顶点的向量长度来嵌入数字水印。该算法具有如下特点:以全局几何特征作为嵌入对象;将一比特的水印信息分布到整个模型之中;水印的嵌入强度自适应于模型的局部特征。实验结果表明该水印算法能抵抗网格简化攻击,噪声攻击,剪切攻击,以及它们的混合攻击,具有很高的稳健性。     

一种3维模型的网格盲水印算法

3维模型的数字水印是数字水印研究的热点之一,鲁棒性、嵌入可读性水印和盲检测是3维模型数字水印的难点所在。从增强3维模型数字水印的鲁棒性出发,提出一种基于局部几何空间的3维模型数字水印算法,它以模型三角网格顶点在其一环邻居顶点为所确定的局部几何空间;通过改变顶点在局部几何空间中的位置来嵌入水印,并以调整其间的夹角来嵌入水印序列的索引,而调整顶点与圆心的距离来嵌入较高比特的二进制数值。本文算法在水印检测时,无需原始模型,且可抵抗平移、旋转、均匀缩放、顶点乱序、剪切及网格简化等攻击。实验结果表明, 该水印算法具有很好的鲁棒性、可读水印的不可感知性和盲水印检测的优势。     

面向3D网格模型的多重数字水印算法

为了解决单盲水印网格算法难以抵抗多种攻击的问题,提出一种鲁棒的3D网格模型的多重数字水印算法.该算法分别对3D网格模型的顶点信息和拓扑信息嵌入2种不同类型的单鲁棒性水印,从而使模型既能抵抗大面积的剪切攻击,又能抗击一定强度的噪声攻击;且在水印提取时不需要原始模型信息.实验结果表明,该算法能有效地提高水印抗平移、旋转、缩放、非均匀缩放、剪切、噪声和顶点乱序等攻击的能力.     

基于几何特征的自适应三维模型数字水印算法

针对三维三角网格模型提出一种稳健的数字水印算法.首先将三维三角网格模型进行仿射变换,以获得模型的旋转不变性和缩放不变性;然后将各顶点邻域内顶点位置的平均差值作为掩蔽因子确定水印嵌入的强度,使得嵌入的水印具有不可见性.实验结果表明:该算法简单,对几何变换、简化、随机噪声和剪切攻击具有较好的鲁棒性.     

一种基于局部坐标系的3维模型盲水印算法

3维模型数字水印是目前数字水印研究的热点之一,鲁棒性和盲检测是3维模型数字水印的难点所在。为了增强3维模型数字水印的鲁棒性、实现盲检测并使检测结果具有可读性,提出了一种基于局部坐标系的3维模型数字水印算法,算法把可读的字符串作为水印信息,通过改变三角网格顶点在其一环邻居所确定的局部坐标系中的位置实现水印的嵌入。该算法在检测水印时,不需要原始模型,而且可以抵抗平移、旋转、缩放、剪切和顶点乱序等攻击。实验结果表明,水印算法具有很好的鲁棒性和不可感知性。     

基于顶点范数三维网格模型抗简化盲水印算法

为提高三维网格模型的数字水印对网格简化攻击的鲁棒性，提出一种基于顶点范数的三维网格模型抗简化盲水印算法。结合网格模型点与面的权重关系计算模型中心，利用中心计算顶点范数，根据水印长度建立顶点范数分组，在嵌入水印时，通过映射函数调整分组内顶点范数均值嵌入水印信息；在检测水印时，计算各集合内均值进行水印信息的盲检测。实验结果表明，该水印算法具有较好的透明性、鲁棒性以及简化攻击抵抗的能力，为三维网格模型的版权保护提供了有效技术支持。     

基于DFT的鲁棒三维网格模型数字水印算法

论文提出了一种基于离散傅立叶变换(DFT)的鲁棒三维网格数字水印嵌入算法,该算法首先将模型中心到顶点的长度进行DFT变换,然后通过修改DFT系数的模来嵌入水印。算法以全局特征作为嵌入对象,并且将1位水印信息分布到整个模型之中。实验结果表明该算法能够抵抗网格简化、加噪声、剪切等类型攻击以及它们的混合攻击,具有很好的鲁棒性。     

全局L∞误差可控的网格模型鲁棒水印算法

针对CAD等工程应用的需要,提出一种具有全局L∞误差控制特性的三角网格模型数字水印算法．在建立多分辨网格的同时在网格顶点坐标上嵌入水印信息,通过局部几何特征进行误差控制．由于水印被冗余地嵌入在模型的整个频带上,该算法可有效地抵抗多种攻击．实验结果表明：文中算法可将水印产生的误差控制在指定的阈值内,且能够抵抗多种水印攻击,具有较好的鲁棒性．     

一个适用于大型三角网格的鲁棒水印算法

针对大型三角网格的特点,提出一个基于外存的鲁棒水印算法。首先对大规模三角网格顶点的重新排序和分组,然后对由分组中顶点到原点的距离组成的序列进行DCT变换,最后将由二值图像调制的水印序列嵌入到经过量化的DCT高频系数中。实验表明,该算法能够抵抗网格噪声、简化、剪切以及仿射变换等攻击,具有良好的不可见性和鲁棒性。     

基于顶点统计特征的三维网格模型盲水印算法

针对三维网格模型盲水印算法鲁棒性和透明性未很好权衡的问题,提出一种基于顶点统计特征的三维网格盲水印算法.在水印嵌入过程中,首先计算顶点到模型中心的距离作为顶点的特征值;根据该特征值对顶点进行分区,并依据特征值的分布将分区分为联合嵌入分区、恢复分区和缓冲分区;然后通过改变联合嵌入分区内归一化后的顶点特征值的分布来嵌入水印,并修改恢复分区中顶点的坐标还原模型中心.文中算法通过综合利用联合嵌入分区、恢复分区和顶点微调方法增强了水印的鲁棒性,并实现了水印的盲检测.实验结果表明,在保持较好的透明性的基础上,该算法能够有效抵抗平移、旋转、均匀缩放、顶点重排序、噪声、平滑、细分和网格重构等常见攻击.     

Double watermarks of 3D mesh model based on feature segmentation and redundancy information

This paper presents a new robust, blind and good imperceptibility 3D mesh double watermarks algorithm. Two different kinds of watermarks are embedded into one 3D mesh model. One watermarking algorithm based on mesh feature segmentation and the DCT transformation, the other based on redundancy information of 3D model. The two watermarks do not disturb each other during embedding and extracting. Several mesh models are applied to test the robustness, imperceptibility and efficiency of the proposed algorithm. The experimental results show that the proposed watermark scheme can not only keep good imperceptibility but also resist various attacks, such as similarity transformations (translation, rotation, scaling and combinations of the three operations), file attack, signal processing attacks (noising, smoothing and vertex coordinate quantization) and connectivity attacks (cropping).     

A Frequency-Domain Approach to Watermarking 3D Shapes

This paper presents a robust watermarking algorithm with informed detection for 3D polygonal meshes. The algorithm is based on our previous algorithm [ 22 ] that employs mesh‐spectral analysis to modify mesh shapes in their transformed domain. This paper presents extensions to our previous algorithm so that (1) much larger meshes can be watermarked within a reasonable time, and that (2) the watermark is robust against connectivity alteration (e.g., mesh simplification), and that (3) the watermark is robust against attacks that combine similarity transformation with such other attacks as cropping, mesh simplification, and smoothing. Experiment showed that our new watermarks are resistant against mesh simplification and remeshing combined with resection, similarity transformation, and other operations..     

Invariant image watermarking using multi-scale Harris detector and wavelet moments

Desynchronization attack is known as one of the most difficult attacks to resist, which can desynchronize the location of the watermark and hence causes incorrect watermark detection. It is a challenging work to design a robust image watermarking scheme against desynchronization attacks. Based on multi-scale Harris detector and wavelet moment theory, we propose a new content based image watermarking algorithm with low computational complexity, good visual quality and reasonable resistance toward desynchronization attacks in this paper. Firstly, the steady image feature points are extracted from the origin host by using multi-scale Harris detector, and the local feature regions (LFRs) are constructed adaptively according to the feature scale theory. Then, the LFRs are image normalized, and significant regions are obtained from the normalized LFRs by utilizing the invariant centroid theory. Finally, the digital watermark is embedded into the LFRs by modifying wavelet moment invariants of the significant regions. By binding the watermark with the geometrically invariant image features, the watermark detection can be done without synchronization error. Experimental results show that the proposed image watermarking is not only invisible and robust against common image processing operations as sharpening, noise adding, and JPEG compression etc, but also robust against the desynchronization attacks such as rotation, translation, scaling, row or column removal, cropping, and local random bend etc.     

抗几何失真的局部数字水印算法

抗几何攻击一直是数字水印中的难点问题,为了更好地解决这个问题,基于图像的几何不变域,提出了一种抗几何失真的局部数字水印算法.算法利用显著性检测器检测到的具有平移、缩放和旋转不变性特性的圆形显著区域来嵌入水印.如何利用显著区域构造不变区域以获得平移、缩放及旋转不变性,以及如何从不变区域中筛选出适合嵌水印的区域,为要解决的重点问题,首先将水印进行几何变换来匹配各个水印嵌入区域的形状,再不可感知地嵌入到各个水印嵌入区域中.还着重讨论了如何利用显著区域获得平移、缩放及旋转不变性.实验表明该算法能很好地抵抗一般的信号处理攻击及旋转、缩放、裁剪和线性变换等几何攻击.     

A robust image watermarking algorithm using SVR detection

Geometric distortion is known as one of the most difficult attacks to resist. Geometric distortion desynchronizes the location of the watermark and hence causes incorrect watermark detection. According to the Support Vector Regression (SVR), a new image watermarking detection algorithm against geometric attacks is proposed in this paper, in which the steady Pseudo-Zernike moments and Krawtchouk moments are utilized. The host image is firstly transformed from rectangular coordinates to polar coordinates, and the Pseudo-Zernike moments of the host image are computed. Then some low-order Pseudo-Zernike moments are selected, and the digital watermark is embedded into the cover image by quantizing the magnitudes of the selected Pseudo-Zernike moments. The main steps of watermark detecting procedure include: (i) some low-order Krawtchouk moments of the image are calculated, which are taken as the eigenvectors; (ii) the geometric transformation parameters are regarded as the training objective, the appropriate kernel function is selected for training, and a SVR training model can be obtained; (iii) the Krawtchouk moments of test image are selected as input vector, the actual output (geometric transformation parameters) is predicted by using the well trained SVR, and the geometric correction is performed on the test image by using the obtained geometric transformation parameters; (iv) the digital watermark is extracted from the corrected test image. Experimental results show that the proposed watermarking detection algorithm is not only robust against common signal processing such as filtering, sharpening, noise adding, and JPEG compression etc., but also robust against the geometric attacks such as rotation, translation, scaling, cropping and combination attacks, etc.     

A robust watermarking scheme for 3D triangular mesh models

Copyright protection of digital media has become an important issue in the creation and distribution of digital content. As a solution to this problem, digital watermarking techniques have been developed for embedding specific information identifying the owner in the host data imperceptibly. Most watermarking methods developed to date mainly focused on digital media such as images, video, audio, and text. Relatively few watermarking methods have been presented for 3D graphical models. In this paper we propose a robust 3D graphical model watermarking scheme for triangle meshes. Our approach embeds watermark information by perturbing the distance between the vertices of the model to the center of the model. More importantly, to make our watermarking scheme robust against various forms of attack while preserving the visual quality of the models our approach distributes information corresponds to a bit of the watermark over the entire model, and the strength of the embedded watermark signal is adaptive with respect to the local geometry of the model. We also introduce a weighting scheme in the watermark extraction process that makes watermark detection more robust against attacks. Experiments show that this watermarking scheme is able to withstand common attacks on 3D models such as mesh simplification, addition of noise, model cropping as well as a combination of these attacks.