关于能量比较的数字音频盲水印方案

提出了一种关于能量比较的数字音频盲水印方案,该方案具有以下特点：根据人类听觉系统掩蔽特性,通过能量比较自适应地寻找最佳水印嵌入点;利用离散余弦变换（Discrete Cosine Transform,DCT）的能量压缩特性,提高数字水印的隐藏效果;实现音频数字水印的高透明性和高鲁棒性的同时,实现水印的盲检测。实验结果表明,算法不但保持了在各种攻击下较好的或更好的鲁棒性,定性和定量两方面的分析,也都显示了嵌入水印后的音频信号可以更好地保留原音频信号的感知质量。     

基于提升小波与DCT的自适应音频水印算法

为了达到版权保护的目的,利用提升小波变换计算速度快、离散余弦变换（DCT）后直流系数的听觉容差性强的特点,提出了一种在提升小波域进行DCT的自适应音频水印算法。原始音频信号经提升小波变换后分解为低频子带和高频子带,对其低频子带进行DCT,将水印序列嵌入到DC系数上。考虑到水印音频信号的不可感知性和鲁棒性之间的平衡问题,采用了水印序列自适应调整嵌入。实验结果表明,该水印算法计算复杂度低,且对噪声、 低通滤波等常见信号攻击及恶意替换操作均表现出很强的鲁棒性。     

基于DCT变换及SVD处理的音频数字水印算法

提出了一种基于离散余弦变换及奇异值分解的音频水印算法。首先对二值水印图像进行奇异值分解求出奇异值,然后对所得奇异值进行基于音频信号变换域性质的调制,并对音频信号进行离散余弦变换并计算水印嵌入点,最后将经过调制的水印信号嵌入。仿真试验证明这种自适应音频数字水印算法具有稳健性和不可觉察性。     

基于多级离散余弦变换的鲁棒数字水印算法

将多级离散小波变换的"多级"思想引入到离散余弦变换中,并对多级离散余弦变换的特性进行了分析,在此基础上提出了一种基于多级离散余弦变换的数字水印算法,该算法从多级离散余弦变换系数中选择适当的位置嵌入水印信息.实验结果表明文中算法的鲁棒性优于常规基于离散余弦变换的数字水印算法,并且它的实时性不受多级变换的影响.此外,该文对多级离散余弦变换中变换系数和变换级数的选择进行了研究,实验结果表明合理选择变换系数进行二级变换可以获得最佳性能.     

基于声道低频能量比的MP3压缩域音频水印算法

为了解决目前大多音频水印算法在应用于MP3音频时存在的效率低下、鲁棒性与不可感知性较难平衡等问题,提出基于MP3帧声道间低频能量的压缩域音频水印算法。该算法的嵌入和提取过程可分别在MP3压缩和解压缩的过程中完成,能大大提高水印的嵌入提取效率。而且由于低频能量具有较好的稳定性,算法利用MP3编解码过程中生成的改进离散余弦变换（MDCT）系数计算得到声道内低频能量,将左右声道内低频能量之比以固定步长量化,最终根据量化结果调整相应的MDCT系数实现水印嵌入;同时,结合不同比例因子频带能量的占比在计算声道内低频能量前对水印嵌入频带进行了筛选,从而能保证水印鲁棒性与不可感知性的平衡。实验显示,该算法可以在维持原始音频可听性的基础上实现对各种类型攻击较好的鲁棒性,尤其是可以抵抗MP3重压缩的攻击。     

一种改进的魔方数字水印算法研究

为了提高数字水印算法的安全性和鲁棒性,在研究了各种常见的水印算法优缺点的基础上,提出了一种改进的基于魔方概念的数字水印算法。首先通过魔方混沌算法将原始水印转化为噪声信号,以提高水印安全性。再结合离散余弦变换(DCT)、离散小波变换(DWT)和矩阵奇异值分解(SVD)嵌入水印,以提高水印的不可见性和鲁棒性。实验结果表明,在确保不可见性的基础上,水印信息在噪声干扰、图像处理、图像压缩下具有很好的鲁棒性。     

基于二维混合变换(DCT-DWT)的图像水印算法

本文首先分析现有的离散余弦变换(DCT)和小波变换(DWT)结合的数字图像水印算法;然后,给出二维混合变换(DCT-DWT)的定义,性质,算法;最后提出基于DWT-DCT混合变换的嵌入和检测水印的算法。试验结果:该算法有很好的鲁棒性。     

基于MCLT变换的音频数字水印技术

在网络与数字信息给人们带来方便的同时，也给人们带来了隐患：敏感信息可能轻易地被窃取、篡改、非法复制和传播等．信息的安全与保密显得越来越重要，信息安全已成为人们关心的焦点，也是当今信息领域的研究热点之一．提出了基于MCLT变换的谱弯折音频水印算法，利用谱弯折技术，通过调整MCLT变换的角频率，可将视觉可辨的二值图像嵌人音频之中，实现水印在整个频域嵌入，算法的最大优点是嵌入量较大．经实验验证，认为谱弯折方法对MP3压缩、重采样等的攻击相当脆弱，不具备鲁棒性，属半易碎型音频水印．     

一种基于DCT和SVD的音频水印算法

提出一种基于离散余弦变换(DCT)和奇异值分解(SVD)的音频水印算法.该算法将原始音频进行分段后再分块,对每一块进行DCT 变换,利用Zig-Zag算法将变换后的系数分成4个象限,通过对每个象限进行SVD变换得到对角阵,并在对角阵的第1个元素内嵌入水印.实验结果证明,该算法具有良好的透明性,在嵌入强度为0.2时峰值信噪比较高,同时可以抵抗重采样、回声、噪声等攻击,具有较高的鲁棒性.     

A robust image watermarking scheme in DCT domain based on adaptive texture direction quantization

This paper proposes a novel robust image watermarking scheme in Discrete Cosine Transform (DCT) domain for active forensics. We investigate the relation between the positions and the modification magnitudes of DCT coefficients and directions of texture blocks. By exploring such relation, a direction-coefficient mapping is designed. First, the texture direction of each image block is estimated by Gabor filter. And then, according to the direction-coefficient mapping, one watermark bit is embedded into each block along its texture direction. Compared with existing schemes, the proposed method utilizes the direction features of texture blocks better . Therefore, the improvements in watermarked image quality and the robustness of watermark signal against image processing attacks are both achieved.

     

A source coding scheme for authenticating audio signal with capability of self-recovery and anti-synchronization counterfeiting attack

Authenticating the veracity and integrity of digital media content is the most important application of fragile watermarking technique. Recently, fragile watermarking schemes for digital audio signals are developed to not only detect the malicious falsification, but also recover the tampered audio content. However, they are fragile against synchronization counterfeiting attack, which greatly narrows the applicability of audio watermarking schemes. In this paper, a novel source coding scheme for authenticating audio signal based on set partitioning in hierarchical trees (SPIHT) encoding and chaotic dynamical system with capability of self-recovery and anti-synchronization counterfeiting attack is proposed. For self-recovery feature, the compressed version of audio signal generated by SPIHT source coding and protected against maliciously tampering by repeated coding is embedded into the original audio signal. Besides, for robustness against synchronization counterfeiting attack feature, based on the position and content of audio section, check bits are generated by Hash algorithm and chaotic sequence, and taken as part of fragile watermark. Simulation results show the self-embedding audio authentication scheme is recoverable with proper audio quality, and it has capability against synchronization counterfeiting attack.

     

A blind watermark algorithm in SWT domain using bivariate generalized Gaussian distributions

Imperceptibility, robustness, and payload are three main requirements of any audio watermarking systems to guarantee desired functionalities, but there is a tradeoff among them from the information-theoretic perspective. Generally, in order to enhance the imperceptibility, robustness, and payload simultaneously, the human auditory system and the statistical properties of the audio signal should be fully taken into account. The statistical model based transform domain multiplicative watermarking scheme embodies the above ideas, and therefore the detection and extraction of the multiplicative watermarks have received a great deal of attention. Although much effort has been made in recent years, improving the ability of imperceptibility, watermark capacity, and robustness at the same time remains a challenge within the audio watermarking community. In this paper, we propose a blind audio watermark decoder in stationary wavelet transform domain based on bivariate generalized Gaussian distributions, wherein both the local statistical properties and inter-scale dependencies of the stationary wavelet transform coefficients of digital audio are taken into account, and also the adaptive nonlinear watermark embedding strength functions are designed. The results of our tests with different host audios, digital watermarks, and various attacks, we experimentally confirm that the proposed approach performs well compared to the state-of-the-art audio watermarking methods.

     

基于视觉模型和整数余弦变换的数字水印算法*

通过引入整数余弦变换与Hash函数方法相结合,在视觉模型框架下提出了一种新的数字水印算法。整数变换的引入,提高了运算速度和图像质量;视觉模型引入,使得水印算法抗JPEG压缩以及其他图像处理方法能力强。该水印方案加密方法符合公开密码体制,具有高度安全特性。     

基于视觉模型和整数余弦变换的数字水印算法

通过引入整数余弦变换与Hash函数方法相结合，在视觉模型框架下提出了一种新的数字水印算法。整数变换的引入，提高了运算速度和图像质量；视觉模型引入，使得水印算法抗JPEG压缩以及其他图像处理方法能力强。该水印方案加密方法符合公开密码体制，具有高度安全特性。     

一种用于内容完整性保护的脆弱数字音频水印算法

提出了一种用于内容完整性保护的脆弱数字音频水印算法 ,该算法首先将视觉可辨的二值水印图像降维成一维水印序列并对其进行随机置乱 ,再从原始数字音频信号中随机选取采样数据并进行快速傅立叶变换 (FFT) ,最后结合人类听觉系统 (H AS)计算可感知噪声阈值 JN D(Just Noticeable Distortion,或称为临界可见失真 ) ,并依此选取FFT系数通过量化处理嵌入水印信息 .该算法提取水印信息时不需要原始数字音频信号 .仿真结果表明 :该脆弱音频水印算法不仅具有较好的透明性 ,而且对诸如叠加噪声、有损压缩、低通滤波、重新采样、重新量化等攻击均具有较好的鲁棒性     

稳健局部特征非下采样小波域数字水印

目的 基于数字水印技术的音乐作品版权保护是学术界的研究热点之一,多数数字音频水印方案仅仅能够对抗简单的常规信号处理,无法有效抵抗破坏性较强的一般性去同步攻击。为此,提出了一种基于稳健局部特征的非下采样小波域数字水印算法。方法 利用非下采样小波域平滑梯度检测算子从载体音频中提取稳定的音频特征点,结合数字音频样本响应确定局部特征音频段,采用量化调制策略将数字水印信号重复嵌入局部特征音频段中。结果 选取4段典型的采样频率为44.1 kHz、量化精度为16 bit、长度为15 s的单声道数字音频信号作为原始载体进行测试,并与经典算法在不可感知性和鲁棒性两方面进行对比。结果表明,本文算法在含水印音频与原始载体音频间的信噪比平均提升了5.7 dB,同时常规攻击和去同步攻击下的平均检测率分别保持在0.925和0.913,高于大多数传统算法,表明了本文算法具有较好的不可感知性。在常规信号处理（MP3压缩、重新量化、重新采样等）和去同步攻击（幅度缩放、随机剪切、音调伸缩、DA/AD转换、抖动等）方面均具有较好的鲁棒性。结论 本文利用描述能力强且性能稳定的平滑梯度刻画局部数字音频性质,提出一种基于平滑梯度的非下采样小波域音频特征点提取方法,有效解决了音频特征点稳定性差且分布极不均匀的缺点,提高了数字音频水印对音调伸缩、随机剪切、抖动等攻击的抵抗能力。     

一种基于均值量化的抗去同步攻击数字水印算法

基于量化调制的音频水印方案以其原理简单、操纵灵活等特点,已引起人们广泛关注,但现有方案不同程度地存在鲁棒性较差等不足之处.结合音频统计均值稳定特性及同步码技术,提出了一种新的数字音频水印嵌入算法,该算法选取稳健的16位巴克码作为同步标记,通过量化音频样本统计均值嵌入同步码,同时结合听觉掩蔽特性量化低频小波系数平均值嵌入数字水印.仿真实验结果表明,本算法不仅具有较好的不可感知性,而且对常规信号处理(MP3压缩、低通滤波、添加噪声、均衡化等)和去同步攻击(随机剪切、幅度缩放、抖动等)均具有较好的鲁棒性.     

A new digital watermarking evaluation and benchmarking methodology using an external group of evaluators and multi‐criteria analysis based on ‘large‐scale data’

Digital watermarking evaluation and benchmarking are challenging tasks because of multiple evaluation and conflicting criteria. A few approaches have been presented to implement digital watermarking evaluation and benchmarking frameworks. However, these approaches still possess a number of limitations, such as fixing several attributes on the account of other attributes. Well‐known benchmarking approaches are limited to robust watermarking. Therefore, this paper presents a new methodology for digital watermarking evaluation and benchmarking based on large‐scale data by using external evaluators and a group decision making context. Two experiments are performed. In the first experiment, a noise gate‐based digital watermarking approach is developed, and the scheme for the noise gate digital watermarking approach is enhanced. Sixty audio samples from different audio styles are tested with two algorithms. A total of 120 samples were evaluated according to three different metrics, namely, quality, payload, and complexity, to generate a set of digital watermarking samples. In the second experiment, the situation in which digital watermarking evaluators have different preferences is discussed. Weight measurement with a decision making solution is required to solve this issue. The analytic hierarchy process is used to measure evaluator preference. In the decision making solution, the technique for order of preference by similarity to the ideal solution with different contexts (e.g., individual and group) is utilized. Therefore, selecting the proper context with different aggregation operators to benchmark the results of experiment 1 (i.e., digital watermarking approaches) is recommended. The findings of this research are as follows: (1) group and individual decision making provide the same result in this case study. However, in the case of selection where the priority weights are generated from the evaluators, group decision making is the recommended solution to solve the trade‐off reflected in the benchmarking process for digital watermarking approaches. (2) Internal and external aggregations show that the enhanced watermarking approach demonstrates better performance than the original watermarking approach. © 2016 The Authors. Software: Practice and Experience published by John Wiley & Sons Ltd.     

A new DCT audio watermarking scheme based on preliminary MP3 study

In this paper, a new audio watermarking scheme operating in the frequency domain and based on neural network architecture is described. The watermark is hidden into the middle frequency band after performing a Discrete Cosine transform (DCT). Embedding and extraction of the watermark are based on the use of a back-propagation neural network (BPNN) architecture. In addition, the selection of frequencies and the block hiding the watermark are based on a preliminary study of the effect of MP3 compression at several rates on the signal. Experimental results show that the proposed technique presents good robustness and perceptual quality results. We also investigate the application of the proposed technique in video watermarking. Traditional techniques have used audio channel as supplementary embedding space and adopt state-of-the art techniques that resist to MP3 compression attack. In these techniques, the MPEG compression attack is only evaluated on the video part and the audio part is kept unaffected. In this paper, we adapt the preliminary MP3 study to video watermarking technique but with a preliminary study of the MPEG compression applied to the audio channel. Here again, we notice that the application of the preliminary MPEG study to the audio channel improves the robustness of the video watermarking scheme though keeping high-quality watermarked video sequences.     

BCH coding and intelligent watermark embedding: Employing both frequency and strength selection

This paper presents a novel approach of adaptive visual tuning of a watermark in Discrete Cosine Transform (DCT) domain. The proposed approach intelligently selects appropriate frequency bands as well as optimal strength of alteration. Genetic Programming (GP) is applied to structure the watermark by exploiting both the characteristics of human visual system and information pertaining to a cascade of conceivable attacks. The developed visual tuning expressions are dependent on frequency and luminance sensitivities, and contrast masking. To further enhance robustness, spread spectrum based watermarking and Bose–Chadhuri–Hocquenghem (BCH) coding is employed. The combination of spread spectrum sequence, BCH coding and GP based non-linear structuring makes it extremely difficult for an attacker to gain information about the secret knowledge of the watermarking system. Experimental results show the superiority of the proposed approach against the existing approaches. Especially, the margin of improvement in robustness will be of high importance in medical and context aware related applications of watermarking.