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.     

基于代价策略的H.264/AVC半脆弱水印算法

In order to solve some existing problems on detecting malicious tampering by video watermarking based on H.264/AVC video compression standard,a semi-fragile video watermarking algorithm for H.264/AVC based on cost strategy was proposed.To further improve the robustness of the feature codes in semi-fragile video watermarking algorithm,a new generation algorithm for feature codes by eliminating the correlation of them was proposed.In order to meet the requirement that the semi-fragile watermarks should be uniformly embedded into the video frames to locate the tampered region accurately,a minimal cost function was introduced to select a DCT coefficient in the 4 × 4 block residual to embed watermark which had minimal impact on the video quality and bit rates.Experimental results show that the proposed algorithm can significantly reduce impact on video quality and bit rate because of embedding the watermarking by adopting the minimum cost function and it is sensitive to malicious manipulations.The retrieved feature code and watermarking can detect and locate malicious manipulations.     

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。     

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.     

A real-time dual watermarking algorithm of H.264/AVC video stream for Video-on-Demand service

A real-time dual watermarking algorithm of H.264/AVC compressed video is proposed for Video-on-Demand (VOD) service. The copyright information and user information are modulated by CDMA spreading strategies as watermark. At the encoder side, copyright information is embedded into the first non-zero coefficient of Intra 4 × 4 coded blocks in the luminance components of I frames. An effective error compensation mechanism is simultaneously introduced into the embedding process, which strictly restricts the distortion caused by quantization and watermark embedding within a step size of quantization. At the server side, a XOR based mapping rule is utilized for watermark embedding because the number of non-zero coefficients after quantization is quite less in P frames. Every two bits of the private user information is mapped to three non-zero coefficients of P frames. Experimental results on test sequences demonstrate that the proposed approach has just slight influence on bit rate and PSNR with real-time performance for VOD services, and achieves the dual purposes of copyright protection and pirate tracking.     

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.     

Robust reversible watermarking scheme using Slantlet transform matrix

The need for a robust reversible watermarking method has recently attracted more attention. This paper presents a novel robust reversible watermarking scheme based on using the Slantlet transform matrix to transform small blocks of the original image and hiding the watermark bits by modifying the mean values of the carrier subbands. The problem of overflow/underflow has been avoided by using histogram modification process. Extensive experimental tests based on 100 general images and 100 medical images demonstrate the efficiency of the proposed scheme. The proposed scheme has robustness against different kinds of attacks and the results prove that it is completely reversible with improved capacity, robustness, and invisibility in comparison with the previous methods.     

位图数字水印的算法研究与实现

数字水印技术广泛应用于多媒体产品的版权保护。本文提出并实现了一种位图水印的嵌入和检测的思想。这种方法采用DCT算法,对图像进行分块处理,同时充分考虑人类视觉特性降低计算量,从图像实验结果可以看出其嵌入与检测的效果比较良好,同时水印的隐蔽性很好,直观性很强,而且可以很好的抵抗剪切、压缩、平滑等图像处理操作。