基于数字广播信令聚合的高可靠应急传输

地面数字广播系统主要用于提供音视频通信服务,可以应用于应急情况下的信息发布。但是,在应急场景下,例如战争或自然灾害发生时,发射系统往往会遭到损坏,很难实现可靠信息发布。针对上述问题,以欧洲地面数字广播系统为例,提出了一种基于数字广播信令聚合的高可靠应急传输方法,用于低发射功率下实现短消息数据的高可靠性传输。该方法在某预先设定的固定传输模式下,利用节省的信令部分承载短消息数据,并以GF(16)域上码率为1/2的多进制低密度奇偶校验码编码和重复编码作为信道编码方案,以二进制相移键控作为调制方式。进一步,利用软件无线电平台在开放环境下对所提出的方法进行测试验证。测试结果表明,本方法能够很好地实现应急短消息数据的高可靠传输,该方案可以扩展到其它数字广播系统。     

自适应小波域数字音频水印嵌入算法研究

以整型提升小波变换、人类听觉掩蔽特性、数字音频局部邻域特性为基础，提出了一种自适应小波域数字音频水印嵌入算法，该算法具有以下特点：（1）结合人类听觉系统的掩蔽特性，实现了水印嵌入位置的自适应确定；（2）引入了高效的整型提升小波变换；（3）利用数字音频的局部邻域特性，实现了数字水印嵌入深度的智能调节；（4）数字水印信息的提取不需要原始音频信号．对比实验表明：该自适应数字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（特别是叠加噪声与低通滤波）。     

基于离散余弦变换的自适应数字音频水印技术研究

提出了一种将灰度图像嵌入到音频信号的数字水印算法 .该算法以包含丰富信息的灰度图像作为数字水印 ,首先利用 DCT静态图像压缩技术 ,将二维数字水印 (灰度图像 )编码成一维二进制序列并进行随机置乱 ,再对数字音频信号进行分段处理并依据人类听觉系统 (HAS)择段做离散余弦变换 (DCT) ,最后在离散余弦变换域内通过修改中高频 DCT系数完成水印信息的自适应嵌入 .实验结果表明 :该自适应数字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     

基于差值抖动调制的鲁棒数字水印

针对数字图像版权保护问题,提出了一种新的鲁棒水印方案.该方案首先对水印进行扩频调制,然后随机选取图像8×8分块DCT变换后的中低频系数对来嵌入水印信息,为了使水印能够抵抗JPEG压缩,提出了基于差值抖动调制的嵌入方法.最后对影响水印鲁棒性和不可见性的主要因素进行了分析.实验结果表明,该方案不仅能够抵抗JPEG压缩和剪切攻击,而且能够抵抗一定程度的低通滤波攻击.     

基于内容的自适应小波域数字音频水印算法研究

以整型提升小波变换、静态图像压缩编码、人类听觉系统（HAS）为基础，提出了一种将灰度图像（即二维数字水印）嵌入到数字音频信号的新水印算法．该算法具有以下特点：（1）应用静态图像压缩编码技术，实现了以灰度图像作为水印信号的数字音频水印算法；（2）充分利用人类听觉系统（HAS），实现了二维数字水印的自适应嵌入，增强了算法的透明性和鲁棒性，（3）二维数字水印的提取不需要原始音频信号．仿真实验表明：该自适应数字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．     

基于Shamir秘密共享方案和零水印的音频水印算法

提出一种基于Shamir秘密共享方案和零水印技术的数字水印算法。该算法首先将音频信号分成n段,并根据Shamir秘密共享方案将水印信息分成n份,然后对n段音频信号进行离散小波分解,将水印信息分存到相应的n段音频信号的低频系数中,然后对低频系数运用零水印技术构造鲁棒水印。实验表明,该算法中的零水印对滤波、有损压缩等常见水印攻击方式有较强的鲁棒性,能达到音频作品版权保护的目的,同时分存的水印信息不仅对音频信号的整体攻击具有较强的敏感性,可以达到内容认证的目的,而且能够抵抗剪切以及对音频文件局部的攻击,并确定被攻击的位置。     

一种数字电视广播系统中的版权保护方案

本文研究了数字电视广播中的版权保护方案,提出从视频接口和节目内容传输两个环节中进行版权的保护。针对视频接口提出一种安全认证加密机制。在接收或录制设备端,提供授权的解密方法,实现加密数据流的播放和录制。针对内容传输提出应用基于频域的主动水印算法进行广播监视,讨论了数字电视网络系统中基于水印的访问控制模型,以及数字水印的嵌入与提取原理。     

基于回归型支持向量机的数字图像水印新算法

以回归型支持向量机（Support Vector Regression,SVR）理论为基础,提出一种数字图像水印新算法.该算法能够结合图像局部相关性,选取稳定的特征向量并获得SVR训练模型,进而利用SVR训练模型嵌入和提取数字水印信息.该算法以保证不可感知性和鲁棒性的良好平衡为前提,实现了数字水印的盲检测.仿真实验表明,本文算法不仅具有较好的不可感知性,而且对叠加噪声、JPEG压缩、锐化、平滑滤波、对比度增强等常规处理及扭曲、剪切等几何攻击均具有较好的鲁棒性,其整体性能明显优于现有SVM图像水印方案.     

井下数字安全广播系统的设计

针对传统的定压广播、局部扩音电话及小灵通等矿用广播系统的缺点,提出了一种井下数字安全广播系统的设计方案,介绍了该系统的整体结构及软、硬件设计方法。该系统采用Ogg Vorbis音频编码方式,以CAN总线为数据传输方式,可实现远程低速率音频传输。应用结果表明,该系统具有较好的音频还原能力。     

A novel reversible robust watermarking algorithm based on chaotic system

Reversible watermarking can be applied to the protection for important digital media, such as medical and military image, it allows the watermark to be extracted and the original image to be restored completely, but reversible watermarking with stronger robustness is seldom discussed in existing literature. In this paper, a novel reversible watermarking algorithm based on chaotic system is proposed; chaotic system is not only used to search space of reversibility of the scheme, but also used to randomly select the position of watermarking embedding. Consequently, the proposed scheme achieves larger threshold space of reversibility and better performance of security. For some specific thresholds, the proposed algorithm is not only reversible, but also has stronger robustness against image compression. The experimental results show that the ergodicity and sensitivity to initial values of chaotic system play an important role in reversible watermarking algorithm, and the proposed scheme can achieve balance between reversibility and robustness with the help of chaotic system.     

基于三维整数小波变换的视频水印算法

随着计算机和网络技术的快速发展,数字水印技术正成为一种保护数字作品知识产权的有效方法.针对数字视频的版权保护,提出一种基于三维整数小波变换的视频水印算法.利用视频场景分割将视频信号切分成不同场景,然后随机选择一场景中视频序列进行三维整数小波变换.采用对小波系数进行均值量化的方法嵌入水印信息,水印提取过程中不需要原始视频信号.该算法实现简单,可满足实时性要求.实验结果表明,该水印方案对于帧丢失、帧插入等时间域去同步攻击以及MEPG有损压缩等具有很好的鲁棒性.     

一种新的大容量数字音频水印嵌入算法

提出了一种新的大容量数字音频水印嵌入算法．该算法具有以下特点：（1）以整型小波变换为基础，不仅降低了舍入误差，而且提高了音频水印的嵌入与检测速度；（2）采纳分段变换及整体修改策略，增强了数字水印嵌入的稳定性；（3）以灰度图像作为数字水印，不仅数据容量大，而且更具层次感和多样性；（4）以保证不可感知性和鲁棒性的良好平衡为前提，实现了数字水印的盲检测．仿真实验表明：所提出的算法不仅具有较好的不可感知性，而且对诸如重新采样、重新量化、低通滤波、MP3压缩、叠加噪声等攻击均具有较好的鲁棒性．     

一种基于DCT和Logistic Map的医学图像鲁棒多水印方法

数字医疗系统在便利了医学信息的存储、传输的同时也带来了信息安全问题, 针对医学图像的安全性提出一种适用于医学图像认证和保护的鲁棒多水印方法。通过DCT获取医学图像的视觉特征向量来进行多水印的嵌入与提取, 使用混沌加密技术对多水印进行预处理来提高水印信息的安全性, 并结合零水印概念得到可抗击常规攻击和几何攻击的水印。实验结果表明, 该方法可以有效地提取水印信息, 并且有较好的不可见性和鲁棒性。此外, 与现存的水印技术相比, 该方法不仅可以降低水印嵌入的复杂度, 而且可以提高水印嵌入的容量, 有更好的灵活性和实用性。     

Dual purpose FWT domain spread spectrum image watermarking in real time

Spread spectrum (SS) watermarking for multimedia signal becomes appealing due to its high robustness attribute and is used widely for various applications. Some of these applications essentially demand development of low cost algorithms so that they can be used for real time services such as broadcast monitoring, security in communication etc. In recent time one popular non-conventional application of digital watermarking becomes promising that assesses blindly the QoS (quality of services) of the multimedia services which is expected to be offered by the future generation mobile radio network. Majority of the existing SS watermarking schemes suffer from high computation cost and complexity leading to the difficulty for real time implementation and limits their usage for the above mentioned applications. This paper proposes fast Walsh transform (FWT) based SS image watermarking scheme that serves the dual purposes of authentication in data transmission as well as QoS assessment for digital media through dynamic estimation of the wireless channel condition. Fast Walsh transform offers low computation cost for implementation, smaller change in image (multimedia signal) information due to data embedding and ease of hardware realization. VLSI implementation using field programmable gate array (FPGA) has been developed to make it suitable for real time implementation.     

一种新颖的灰度图像盲水印算法

提出了一种小波域的数字水印算法,以一幅(64×64×8)bit的灰度图像为水印嵌入宿主图像,而且实现了盲检测。为了增强水印信号的安全性,采用了基于混沌和位平面的水印加密算法,实验表明,该算法有很好的不可见性,对压缩、滤波等操作有较强的鲁棒性。通过分析提取的水印,还可以对图像的篡改进行精确的定位。     

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。     

A novel CRT-based watermarking technique for authentication of multimedia contents

Digital watermarking techniques have been proposed as a solution to the problem of copyright protection of multimedia data. In this paper, we propose a novel Chinese remainder theorem (CRT)-based technique for digital watermarking. The use of CRT for this purpose provides additional security along with resistance to some familiar attacks. We have shown that this technique is quite resilient to addition of the noise. We have compared performance of the proposed technique with recently reported two singular value decomposition (SVD)-based watermarking techniques and shown its superior performance in terms of tampering assessment function (TAF), computational efficiency and peak signal to noise ratio (PSNR). For example, the embedding time of the proposed CRT-based scheme is 6 and 3 times faster than the SVD-based Schemes 1 and 2, respectively. This technique can also be applied to document, audio and video contents.     

A semi-fragile watermarking scheme for authenticating audio signal based on dual-tree complex wavelet transform and discrete cosine transform

In this paper, a novel semi-fragile watermarking scheme for authenticating an audio signal based on dual-tree complex wavelet transform (DT-CWT) and discrete cosine transform (DCT) is proposed. Specifically, the watermark data are efficiently inserted into the coefficients of the low-frequency sub-band of DT-CWT taking advantages of both DCT and quantization index modulation (QIM). First, the original digital audio signal is segmented and then performed with DT-CWT. Second, based on the energy compression property, the low-frequency sub-band coefficients of the DT-CWT domain are performed with DCT, and the DC component is utilized to embed one distorted watermark bit by the QIM technique. Finally, inverse DCT and DT-CWT are orderly implemented on the watermarked coefficients of each audio segment to get a watermarked audio signal. Simulation results show that the hybrid embedding domain constructed by DT-CWT and DCT is effective, and the proposed watermarking scheme is not only inaudible, but also robust against content persistent non-malicious audio signal processing operations, such as MP3 compression, noise addition, re-sampling, re-quantization, etc. Furthermore, the proposed scheme can effectively authenticate the veracity and integrity of audio content and greatly expands the applicability of the audio watermarking scheme.     

一种新的基于DWT、DCT和SVD的鲁棒水印算法

本文提出一种新的基于离散小波变换(DWT)、离散余弦变换(DCT)和矩阵奇异值分解(SVD)的鲁棒水印算法.首先按照本文提出的小波分解准则对载体图像进行四层小波分解,取第四层的低频子图与三个高频子图;同样对水印图像进行小波分解得到低频子图与三个高频子图.然后用DCT、SVD方法,结合本文提出的相互嵌入准则将水印图像的低...     

A robust digital audio watermarking scheme based on DWT and Schur decomposition

The vulnerability of digital audio signals for different types of risks requires an imperceptible and robust digital audio watermarking scheme. In this research, we propose creating one such imperceptible and robust hybrid watermarking scheme based on a discrete wavelet transform (DWT) and Schur decomposition hybrid method. The proposed scheme embeds the foreground bits of the watermarking image into the least significant bit of the diagonal coefficients of the triangular matrix S generated from Schur decomposition. Schur decomposition is applied on the second sub-band HL₂ generated from applying a second-level 2D-Haar DWT on the first channel of the original audio signal. We analyze the proposed digital audio watermarking scheme’s performance in terms of signal to noise ratio (SNR), objective difference grades (ODG), and subjective difference grades (SDG) that resulting 81.43, 4.78 and 0.184, respectively. The resulting of payload capacity, NC, and BER are as high as 319.29 bps, 0.9911, and 0.0135, respectively. Experimental results confirm that the proposed scheme is inaudible and robust against common types of attacks such as Gaussian noise, re-quantization, re-sampling, low-pass filter, high-pass filter, echo, MP3 compression, and cropping. In comparison with state-of-the-art audio watermarking schemes, the proposed scheme’s performance is superior in term of imperceptibility, robustness, and data payload size.