Multipurpose image watermarking algorithm based on multistage vector quantization.

The rapid growth of digital multimedia and Internet technologies has made copyright protection, copy protection, and integrity verification three important issues in the digital world. To solve these problems, the digital watermarking technique has been presented and widely researched. Traditional watermarking algorithms are mostly based on discrete transform domains, such as the discrete cosine transform, discrete Fourier transform (DFT), and discrete wavelet transform (DWT). Most of these algorithms are good for only one purpose. Recently, some multipurpose digital watermarking methods have been presented, which can achieve the goal of content authentication and copyright protection simultaneously. However, they are based on DWT or DFT. Lately, several robust watermarking schemes based on vector quantization (VQ) have been presented, but they can only be used for copyright protection. In this paper, we present a novel multipurpose digital image watermarking method based on the multistage vector quantizer structure, which can be applied to image authentication and copyright protection. In the proposed method, the semi-fragile watermark and the robust watermark are embedded in different VQ stages using different techniques, and both of them can be extracted without the original image. Simulation results demonstrate the effectiveness of our algorithm in terms of robustness and fragility.     

Novel watermarking scheme for image authentication using vector quantization approach

In this paper a new invisible watermarking algorithm using vector quantization (VQ) approach for image content authentication application is proposed. At the first stage, a robust verification watermark is embedded using properties of indices of vector quantized image using key based approach. At the second stage, the semi-fragile watermark is embedded by using modified index key based (MIKB) method. Robust watermark andVQenhance the security of the system by providing its double protection. The semi-fragile watermark is utilized for the authentication of the received image. Blind extraction of the watermark is performed independently in two successive steps i.e. in the order of embedding. Further, in oder to classify quantitatively an incidental or intentional attack, which at present is not being followed, a quantitative threshold approach using pixel neighborhood clustering is suggested. The existing methods employ the qualitative approach of identifying incidental or intentional attacks. Imperceptibility of watermarked image is 41 dB on the average, and it is also possible to detect and locate tamper with very high sensitivity. The present scheme is compared with the existing algorithms. The performance of proposed algorithm has been tested on various practical images. It outperforms in distinguishing malicious tampering from content preserving changes and the tampered regions are accurately localized.     

Semi-fragile image watermarking method based on index constrained vector quantisation

A novel semi-fragile digital image watermarking method is presented, based on index constrained vector quantisation, which embeds the watermark information into the compressed bit streams. Simulation results show that the proposed method is robust to JPEG compression and VQ compression with high-performance codebooks but fragile to other image processing operations.     

用于图像篡改定位和恢复的分层半脆弱数字水印算法

设计并实现了一种基于分层的半脆弱数字水印算法,用于图像内容完整性认证,篡改定位和恢复。在嵌入方,将水印信息嵌入到原始图像所有像素的2bit最低有效比特,其中认证水印由奇偶校验码和块与子块之间灰度平均值的比较组成;恢复水印为环面自同构映射块的平均灰度值。在检测方,采用分层思想,分3层对水印进行篡改定位和恢复。实验结果表明,该算法对局部发生的篡改可以有效地检测,精确定位并进行内容恢复,同时能够有效的抵抗矢量量化攻击。     

基于H.264低比特率视频流的半脆弱盲水印算法实现

本文提出一种基于H.264低比特率视频流的半脆弱盲水印方法,通过在H.264特有的的帧内预测和运动向量预测中分别嵌入鲁棒水印和脆弱水印,达到版权保护和内容完整性认证的双重目的.通过在嵌入强度和预测模式选择的拉格朗日乘子中引入H.264量化因子,增强了水印对重量化编码的抵抗力,取得更好的率失真平衡,减小水印嵌入对视频流比特率的影响.该算法可以实现水印的快速嵌入提取,满足视频实时处理的要求,实验结果证明了该算法的有效性.     

DWT域半脆弱音频水印算法

A novel semi-fragile audio watermarking algorithm in DWT domain is proposed in this paper. This method transforms the original audio into 3-layer wavelet domain and divides approximation wavelet coefficients into many groups. Through computing mean quantization of per group, this algorithm embeds the watermark signal into the average value of the wavelet coefficients. Experimental results show that our semi-fragile audio watermarking algorithm is not only inaudible and robust against various common images processing, but also fragile to malicious modification. Especially, it can detect the tampered regions effectively.     

Digital image watermarking technique based on vector quantisation

A digital image watermarking technique based on vector quantisation (VQ) is presented. This technique uses codeword indices to carry the watermark information. The technique is secret and efficient: the watermarked image is robust to VQ compression with the same codebook. The simulation results prove the effectiveness of this technique     

Watermarking based image authentication and tamper detection algorithm using vector quantization approach

In the present work, a novel image watermarking algorithm using vector quantization (VQ) approach is presented for digital image authentication. Watermarks are embedded in two successive stages for image integrity verification and authentication. In the first stage, a key based approach is used to embed robust zero level watermark using properties of indices of vector quantized image. In the second stage, semifragile watermark is embedded by using modified index key based (MIKB) method. Random keys are used to improve the integrity and security of the designed system. Further, to classify an attack quantitatively as acceptable or as a malicious attack, pixel neighbourhood clustering approach is introduced. Proposed approach is evaluated on 250 standard test images using performance measures such as peak signal to noise ratio (PSNR) and normalized hamming similarity (NHS). The experimental results shows that propose approach achieve average false positive rate 0.00024 and the average false negative rate 0.0012. Further, the average PSNR and tamper detection/localization accuracy of watermarked image is 42 dB and 99.8% respectively; while tamper localization sensitivity is very high. The proposed model is found to be robust to common content preserving attacks while fragile to content altering attacks.     

一种基于JPEG压缩的半脆弱水印算法

本文分析了JPEG压缩中的DCT变换和量化过程，根据量化的特性提出了一种半脆弱水印方案，并将水印信息调制为纠错码嵌入JPEG压缩过程的量化系数中，实验证明，此水印方案鲁棒性较强，虚警率低，能较好的检测图像是否被篡改并对篡改定位。     

Grouping strategies for promoting image quality of watermarking on the basis of vector quantization

In this paper, a novel vector quantization (VQ)-based digital image watermarking scheme is proposed which retains high image quality even after embedding. The general scheme of watermarking is to embed a representative digital watermark in the protected image to claim the ownership. The robustness of watermark is important; however, the imperceptibility of embedded images also cannot be ignored. In previous papers, existing greedy technique to group codewords often results in low quality of stego-images. As an improvement to the existing techniques, two new grouping strategies, codebook-sort grouping and bipartite-match grouping are proposed in this paper to improve the quality of stego-images. Moreover, a new VQ encoder, called as shortest-group encoding method is proposed to replace the traditional VQ encoder in the purpose of embedding. Finally, in order to improve the grouping flexibility, two kinds of weights are considered in our approach. Experimental results show that all of the above approaches can improve the quality of stego-images on VQ-based watermarking.     

一种新的基于遗传算法DCT域半脆弱水印算法

半脆弱水印因为在多媒体内容认证方面的重要作用而受到人们密切的关注。为了能够区分偶然攻击与恶意篡改,半脆弱水印需要对一般的内容保护图像操作有一定的鲁棒性。基于此,提出了遗传算法的半脆弱数字图像水印方法。根据图像局部区域的类型自适应地确定图像局部区域的水印嵌入强度,GA用来优化水印的嵌入位置。实验结果证实了所提的算法的优点,表明该方法具有较好的不可见性和鲁棒性,并实现了印刷图像载体版权保护。     

VQ-based digital image watermarking method

A vector-quantisation (VQ)-based watermarking method is presented which utilises the codebook expansion technique. This method is efficient, provides enhanced security and the watermarked image is robust against the effects of VQ compression. Moreover, the watermark extraction can be performed without the original image. Experimental results are presented which demonstrate the effectiveness of this algorithm.     

基于格的灰度级水印技术

提出一个新的灰度级水印算法．首先，使用量化技术对灰度级水印进行预处理，实现灰度级水印的数据压缩；然后，对原始图像进行小波分解，在小波域中使用格矢量量化技术构造水印的嵌人和提取算法．提取水印不需要原图像．为增强水印的安全性，使用混沌序列作为密钥对水印序列进行调制．实验结果表明，与同类算法相比该算法在获得较好感知质量含水印图像的同时提高了水印的鲁棒性．     

一种基于小波变换的图像完整性验证水印算法

针对现有的图像完整性验证水印技术,提出了一种小波域的图像完整性验证水印算法,该算法对小波系数块进行均值量化来实现二值水印信息的嵌入,在鲁棒性和脆弱性方面达到很好的平衡。仿真实验结果证明,该算法能抗常规的非恶意攻击,对于恶意攻击具有很强的识别和定位能力。     

基于小波变换和相对量化的图像数字水印算法

提出了一种基于分块小波变换和相对量化的图像数字水印算法。由于在算法中采用了量化嵌入策略,从而在提取水印时无需原始图像和原始水印。实验结果表明,该算法对嵌入的水印具有很好的透明性,对亮度和对比度调整攻击具有非常强的稳健性,对JPEG压缩、重采样、颜色抖动、平滑和加噪声等常见的图像处理攻击具有很强的稳健性,并且算法思想简单、步骤简便和容易实现。     

基于系数奇偶量化的图像水印算法

文中提出了一种新的基于系数奇偶量化的图像小波域数字水印算法,该算法首先对水印图像进行置乱处理,载体图像的小波变换系数经奇偶量化后,将置乱后的水印图像嵌入其中。算法对小波系数的奇偶量化性能在鲁棒性和水印的不可见性上进行了很好的折衷,实验表明该算法对载体图像的影响较小且具有很好的鲁棒性,可以有效地抵抗JPEG压缩、噪声干扰等常见的攻击。     

A New Audio Watermarking Scheme Based on Singular Value Decomposition and Quantization

In this paper, we propose a new robust and blind audio watermarking algorithm based on singular value decomposition and quantization index modulation. The watermark insertion and extraction methods are based on quantization of the norm of singular values of the blocks. Audio quality evaluation tests show high imperceptibility of the watermark in the audio signal. Simulation results demonstrate that this algorithm is robust against signal-processing and stirmark attacks. The false negative error probability under the proposed scheme is close to zero. Moreover, the proposed algorithm has higher data payload and better performance than the other related audio watermarking schemes available in the literature.     

基于小波系数关系的半脆弱水印方案

提出了基于小波变换系数间关系的半脆弱水印方案，通过构建小波域相邻及相应系数间的关系进行水印嵌入和提取，从而能够在侦测到对图像的恶意篡改的同时，对常见的图像处理仍保持很好的鲁棒性，此外由于对整个系数链进行了关联，所以系统的安全性在原有密匙保护的基础上又有大的提升。     

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。     

基于奇异值分解的半易损水印算法

随着数字图像在报刊杂志、医院、法庭中的广泛应用，越来越需要一种有效的图像认证方法，数字水印技术为上述问题提供了一个潜在的解决方案。本文提出了一种基于分组奇异值分解（SVD）的半易损水印技术，算法将经过伪随机排序的二值图像通过量化策略嵌入到分组SVD分解中最大的奇异值点，提取水印信号无需使用原始图像。仿真实验表明水印是不可察觉的，可将JPEG有损压缩同恶意攻击区分开来，能够准确地定位被篡改的图像内容。