Difference angle quantization index modulation scheme for image watermarking

In this paper, we propose a new angle quantization index modulation (AQIM) method, called the difference AQIM (DAQIM) method. The proposed method aims to improve the watermarking performance against gain attacks. Unlike the original AQIM method (Ourique et al., Angle QIM: a novel watermark embedding scheme robust against amplitude scaling distortions, in: Proceedings of IEEE International Conference on Acoustics, Speech, and Signal Processing, vol. 2, 2005, pp. 797–800), the DAQIM method quantizes the difference of the two angles instead of the angles themselves. The main advantage of the DAQIM method is to disperse the interference to the watermark signal from one angle to more angles. Thus, the watermark has a higher ability to resist attacks. We perform a theoretical analysis of the document-to-watermark ratio (DWR) based on our proposed method. We show that our proposed method can obtain a lower embedding distortion compared to the AQIM and the gradient direction watermarking (GDWM) (Nezhadarya et al., IEEE Trans. Inf. Forensics Secur., 6(4), 2011, 1200–1213), methods under the same robustness and payload conditions. The experimental results demonstrate that our proposed method outperforms common existing methods in terms of the robustness against various attacks such as the JPEG quantization noise, additive white Gaussian noise (AWGN), cropping effect and mean filtering.     

基于超混沌和Slant变换的鲁棒水印算法

为进一步提高水印算法的安全性和抗攻击能力,结合超混沌和Slant变换的优点,提出一种基于超混沌和Slant变换的鲁棒水印算法。首先,在隐藏水印之前采用超混沌系统对水印图像进行加密,提高了待隐藏图像的安全性;其次,将原始载体图像划分成大小为8×8的不重叠分块并对各个分块分别进行Slant变换;最后,将加密后的水印图像隐藏到Slant变换后的直流系数和中频系数中。大量的仿真结果表明,本文算法具有较好的隐蔽性,对JPEG压缩、噪声、滤波、缩放、对比度调整等攻击具有较好的抗攻击能力。与相似算法相比,本文算法具有更好的鲁棒性能。     

基于一次U系统的商业票据防伪的数字水印算法

本文将一次U系统的正交函数系应用到商业票据防伪中,给出了一种新的数字水印算法.通过算法设计和仿真实验分析,该数字水印算法对票据防伪具有算法简单易实现,能够抵抗票据的涂抹、裁剪、JPEG压缩、加噪等攻击的特点.可适用于商业票据的防伪和认证.     

基于视觉显著模型的音视频交叉水印算法

提出一种基于Itti视觉显著模型的音视频交叉水印算法.首先利用音频码流的低通幅值特性生成水印,并嵌入到视频码流中;其次解码视频码流的关键帧Ⅰ帧,获取YUV序列上的亮度(Y)分量,并对其进行显著性分析;最后分块对非显著区域进行DCT变换,并通过量化索引调制嵌入水印.实验结果表明,该算法将嵌入水印后的关键帧平均PSRN值提高了1.678 5 dB,缓解了水印不可见性和鲁棒性的矛盾,实现了音视频码流之间的交叉保护.     

基于JPEG图像压缩技术的水印应用研究

本文基于PGEG图像有损压缩技术提出了一种数字图像水印算法实现过程。这种算法不会对图像压缩质量有明显的影响,可以有效对图片信息进行准确性和可靠性验证,达到检测图象真实性目的。     

Game Theory Based False Negative Probability of Embedded Watermark Under Unintentional and Steganalysis Attacks

Steganalysis attack is to statistically estimate the embedded watermark in the watermarked multimedia,and the estimated watermark may be destroyed by the attacker.The existing methods of false negative probability,however,do not consider the influence of steganalysis attack.This paper proposed the game theory based false negative probability to estimate the impacts of steganalysis attack,as well as unintentional attack.Specifically,game theory was used to model the collision between the embedment and steganalysis attack,and derive the optimal building embedding/attacking strategy.Such optimal playing strategies devote to calculating the attacker destructed watermark,used for calculation of the game theory based false negative probability.The experimental results show that watermark detection reliability measured using our proposed method,in comparison,can better reflect the real scenario in which the embedded watermark undergoes unintentional attack and the attacker using steganalysis attack.This paper provides a foundation for investigating countermeasures of digital watermarking community against steganalysis attack.     

Variable-dimensional vector modulation for perceptual-based DWT blind audio watermarking with adjustable payload capacity

A variable-dimensional vector modulation (VDVM) scheme is introduced to maximize the efficiency of the norm-space DWT-based blind audio watermarking technique. This flexible scheme allows the watermarking algorithm to reach a balance between robustness and capacity, while the imperceptivity is always ensured. The imperfection of applying quantization index modulation in the open-loop case has been rectified. The effectiveness of the proposed scheme is proven using the perceptual evaluation of audio quality (PEAQ) and bit error rates of recovered watermarks under various signal processing attacks. Experimental results show that the proposed VDVM scheme is comparable to other recently developed methods in robustness and imperceptivity even at a capacity as high as 301.46 bps. Such a capacity can be further doubled by halving the dimension of the involved DWT vector, while the robustness is still maintained at a satisfactory level.     

Robust and blind watermarking technique in DCT domain using inter-block coefficient differencing

In this paper, a robust blind watermarking technique, based on block-based DCT coefficient modification is proposed. The difference between two DCT coefficients of the adjacent blocks at the same position is calculated. Depending upon the watermark bit to be embedded; this difference is brought in a particular predefined range which is achieved by modifying one of the two DCT coefficients. The amount of modification to a DCT coefficient of a block depends upon the scaling variable, DC coefficient and median of certain zig-zag ordered AC coefficients of that block. The robustness of the proposed scheme has been examined for various singular and hybrid attacks. Comparison results reveal that the proposed technique has a higher degree of robustness against various singular and hybrid attacks. Further a watermark of good quality is extracted even after various simultaneous attacks on the system.     

FPGA implementation of reversible watermarking in digital images using reversible contrast mapping

Reversible contrast mapping (RCM) and its various modified versions are used extensively in reversible watermarking (RW) to embed secret information into the digital contents. RCM based RW accomplishes a simple integer transform applied on pair of pixels and their least significant bits (LSB) are used for data embedding. It is perfectly invertible even if the LSBs of the transformed pixels are lost during data embedding. RCM offers high embedding rate at relatively low visual distortion (embedding distortion). Moreover, low computation cost and ease of hardware realization make it attractive for real-time implementation. To this aim, this paper proposes a field programmable gate array (FPGA) based very large scale integration (VLSI) architecture of RCM-RW algorithm for digital images that can serve the purpose of media authentication in real-time environment. Two architectures, one for block size (8 × 8) and the other one for (32 × 32) block are developed. The proposed architecture allows a 6-stage pipelining technique to speed up the circuit operation. For a cover image of block size (32 × 32), the proposed architecture requires 9881 slices, 9347 slice flip-flops, 11291 number 4-input LUTs, 3 BRAMs and a data rate of 1.0395 Mbps at an operating frequency as high as 98.76 MHz.