Blind MPEG-2 video watermarking in DCT domain robust against scaling

Watermarking techniques that need no original information during watermark detection, known as blind watermarking, are more desirable than informed ones for practical usage and convenience in watermark extraction. A blind MPEG-2 watermarking technique operating in the DCT (discrete cosine transform) domain is presented, which is generally robust against arbitrary ratio scaling, provided that turbo codes are used for error correction. The method can be directly applied to other block-DCT-based video compression techniques. The main advantage of the scheme is its simplicity, blindness and the ability to tailor the watermark payload in a trade-off with other watermark requirements. As synchronisation is automatically obtained from the frames in the scaled video itself, a connection between the source and the target video is not necessary for watermarking detection     

Localized image watermarking in spatial domain resistant to geometric attacks

Watermark robustness to geometric attacks is still a challenging research field. In this paper, a novel robust image watermarking scheme is proposed for resisting such attacks. Watermark synchronization is first achieved by local invariant regions which can be generated using scale normalization and image feature points. The watermark is embedded into all the local regions repeatedly in spatial domain. During embedding, each circular region is first divided into homocentric cirque regions. Then the watermark bits are embedded by quantizing each cirque region into an “odd” or “even” region using odd–even quantization. In the decoder, an odd–even detector (OED) is designed to extract the watermark from the distorted image directly. Localized embedding achieves good invisibility and repeated insertion enhances watermark robustness. Simulation results show that the proposed scheme is robust to both geometric attacks and traditional signal processing attacks.     

基于噪声模型的DCT域盲水印算法

针对DCT交流系数分布函数的广义高斯分布模型设计了一个盲水印算法,该算法独立于具体图像,具有通用性.实验结果显示,该算法表现出良好的检测性能和对包括JPEG压缩、裁剪、高斯噪声、虚假嵌入在内的多种攻击的鲁棒性;进而,将此算法推广到多重水印嵌入场合,提出了三种重复嵌入策略,增加了嵌入的信息量和嵌入方式的灵活性.     

MPEG-2码流中的数字水印

本文在对标准ＭＰＥＧ－２视频编解码系统深入剖析的基础上,对视频码流内嵌数字水印典型系统Ｈ＆Ｃ算法核心技术进行分析和改进,引入动态水印嵌入控制和ＤＣＴ域水印自适应调制控制对其进行优化。模拟实验表明,改进算法较原有算法能够更合理有效地将水印信息嵌入到视频码流中,同时整体算法系统复杂度也大为下降。     

Secure watermarking scheme against watermark attacks in the encrypted domain

The homomorphic cryptosystems create a great opportunity for secure signal processing (SSP). Watermarking in the encrypted domain provides a promising solution to the security of watermarking. However, the robust performance of the watermarking scheme in the encrypted domain should be carefully considered. In this paper, we propose a robust watermarking scheme in the encrypted domain, which protects the original images from the third party embedders. The hybrid discrete wavelet transform (DWT) and discrete cosine transform (DCT) based method improves the robust performance of the encrypted domain watermarking scheme. The watermark extraction can be performed on both the plaintext and the encrypted domains. We also give an estimation of the expanding factor after watermark embedding in the encrypted domain. At last, we discuss the watermark attacks that are available in the encrypted domain. Taking Haar wavelet transform for example, we conduct the experiments on the visual quality and the robustness of our watermarking scheme, which demonstrate that the entire performance is satisfactory.     

A novel blind robust image watermarking in DCT domain using inter-block coefficient correlation

This paper presents a novel blind watermarking algorithm in DCT domain using the correlation between two DCT coefficients of adjacent blocks in the same position. One DCT coefficient of each block is modified to bring the difference from the adjacent block coefficient in a specified range. The value used to modify the coefficient is obtained by finding difference between DC and median of a few low frequency AC coefficients and the result is normalized by DC coefficient. The proposed watermarking algorithm is tested for different attacks. It shows very good robustness under JPEG image compression as compared to existing one and also good quality of watermark is extracted by performing other common image processing operations like cropping, rotation, brightening, sharpening, contrast enhancement etc.     

Optimisation of enhancement layer DCT coefficients in MPEG-2 SNRscalable video

The authors describe an optimisation algorithm which can be applied to two-layer SNR scalable MPEG-2 video coding, such that bandwidth efficiency is achieved which is comparable to single-layer coding. Our optimised two-layer coder is shown to generate as little as 1% fewer bits than a single-layer coder compared to up to 15% more bits generated by the non-optimised SNR scalable coder     

Blind image watermarking via exploitation of inter-block prediction and visibility threshold in DCT domain

In this paper, the backward-propagation neural network (BPNN) technique and just-noticeable difference (JND) model are incorporated into a block-wise discrete cosine transform (DCT)-based scheme to achieve effective blind image watermarking. To form a block structure in the DCT domain, we partition a host image into non-overlapped blocks of size 8 × 8 and then apply DCT to each block separately. By referring to certain DCT coefficients over a 3 × 3 grid of blocks, the BPNN can offer adequate predictions of designated coefficients inside the central block. The watermarking turns out to be a process of adjusting the relationship between the intended coefficients and their BPNN predictions subject to the JND. Experimental results show that the proposed scheme is able to withstand a variety of image processing attacks. Compared with two other schemes that also utilize inter-block correlations, the proposed one apparently exhibits superior robustness and imperceptibility under the same payload capacity.     

基于Turbo码的DWT-DCT域鲁棒性视频水印算法

本文提出了一种基于Turbo码的DWT域与离散DCT域相结合的视频水印算法. 在该算法中, 先选取视频序列中的关键帧,并对其亮度分量进行一级DWT变换,再对DWT域的逼近子带进行4?的DCT变换,最后在DCT变换的直流系数中嵌入经过伪随机排序和Turbo码编码置乱后的水印信息. 实验结果表明：该算法不仅具有良好的不可见性,而且对各种常见的攻击都具有较好的鲁棒性.     

Blind quality assessment of image and video based on fragile watermarking and robust features

Blind quality assessment is an important feature required by many modern multimedia communication systems. Reduced reference approaches employing fragile watermarking techniques have been proposed earlier for this purpose. This paper proposes an approach which makes use of robust image features and fragile watermarking techniques resulting in a reduced reference strategy. Other than the input image, the approach requires no external information. Robust image features are used to construct the watermark from the image to be transmitted, which is then embedded as a fragile watermark in the image itself. The same features are once again used to construct the reference watermark from the received image, with which the extracted fragile watermark is compared to determine the amount of degradation suffered by it. Construction of the watermark from the image itself, dispenses with the need for embedding an extraneous watermark which must be made known to the user separately. Singular Value Decomposition is used for the extraction of the fragile watermark from the received image while a different approach is used for reduced reference quality assessment of video sequences, making use of consecutive video frames. These form the significant contributions of the present work. The performances of the proposed algorithms have been demonstrated through extensive simulations using different kinds of gray-scale and color images and a number of popularly used test video sequences.

     

DCT系数在数字视频水印技术中的运用

文章提出DCT系数之下的MPEG-2视频水印技术运用方法。这一算法对相关水印信息进行Hash置乱之后嵌入到I帧色度的DC系数之上。该算法把混沌理论、置乱技术以及扩频技术等加以汇总以后全面应用至视频水印体系之中,从而提升了水印所具有的不可预见特性、鲁棒特性以及安全特性。文章对数字视频水印技术进行了概述,阐述了DCT系数在视频水印技术中的运用方法,并分析了DCT系数应用实验的结果。     

一种自适应的帧/场DCT变换在MPEG-2中的应用

结合MPEG-2标准语法详细分析了一种自适应选择帧/场DCT变换的算法，产生了一个符合MPEG-2语义的视频流。     

MPEG-2压缩域中鲁棒性摄像机运动估计算法的研究

在视频检索的很多应用中,比如对象轨迹追踪,都需要首先分离摄像机运动。现提出一种MPEG-2压缩域中鲁棒性摄像机运动估计——自适应尺度残差一致性ASRC（Adaptive-Scale Residual Consensus）算法,只使用P帧的运动向量,并对多重结构噪声可达到80%的击穿点,使MPEG矢量场中奇异值的影响降到最小。对比经典LMedS估计,提出的ASRC具有更好的鲁棒性和击穿点。实验结果显示出令人满意的效果。     

I.McIC: a single-chip MPEG-2 video encoder for storage

I.McIC is a single-chip MPEG-2 video encoder for consumer storage applications. It supports both intra- and inter-coding mode to achieve bit rates from 5-15 Mb/s. It contains a recursive motion estimator, a programmable buffer/bit-rate controller, and a temporal noise-reduction stage. The resulting IC has 4.5×10⁶ transistors and measures 192 mm² in a 0.5-μm process. I.McIC was designed using mainly high-level synthesis tools. High-throughput fixed MPEG functions are performed by dedicated hardware. The remainder is performed in software by an embedded application-specific instruction-set processor with downloadable microcode to suit the IC for different applications of video coding     

Utilizing neighborhood coefficient correlation: a new image watermarking technique robust to singular and hybrid attacks

A new blind digital image watermarking algorithm with watermark embedded in discrete cosine transform (DCT) coefficients is presented in this paper. The proposed scheme exploits correlation between DCT coefficients in neighborhood blocks for embedding. The watermark is embedded by modifying two DCT coefficients, one pertaining to a block in which watermark bit (0 or 1) is to be embedded and the other corresponding to the selected neighborhood block. Both the selected coefficients are modified by a modification factor so that the difference between the pair of coefficients is brought to a predefined zone. This difference between two DCT coefficients is used to extract watermark. The proposed technique has been tested for different attacks like JPEG compression, rotation, cropping, filtering, gaussian noise, salt and pepper noise, histogram equalization etc. It has been observed that the scheme is highly robust not only for the above mentioned attacks used singularly, but also for different possible combinations of simultaneous attacks. A comparison of the proposed technique with some state of art existing algorithms reveals that our scheme provides better results in terms of quality of watermarked images, payload and robustness.     

基于MATLAB的DCT域数字水印技术实现

研究了基于离散余弦变换(DCT)的数字图像水印算法，并借助一种高效实用的编程工具MATLAB，编程使这种算法得以实现，实验结果表明，对于通常的压缩编码，该算法具有足够的稳健性。     

双基预测算法在MPEG-2视频编码中的应用

详细地分析了双基预测算法的实现过程及其优越之处,同时给出了一种切实可行的编码算法,产生了个符合MPEG-2语义的视频流。     

军事通信中基于DCT域直流分量的音频数字水印技术研究

军事通信中,应将确保信息的绝对安全摆在首要位置。目前我军的野战通信以无线通信手段为主,通信双方的身份识别是确保战场无线通信安全的基本前提。基于现役通信装备,为提高战场通信的安全性,设计了基于DCT变换在DC分量嵌入及提取水印的方案,可为身份识别提供保障。通过Matlab仿真,与普遍现行的小波变换(DWT)技术在不可感知性、提取可信度和抗干扰性三个方面进行对比,结果表明该方法更具有优势,更适用于战场通信环境的身份识别。     

Forward error control for MPEG-2 video transport in a wireless ATM LAN

The possibility of providing multimedia services to mobile users has led to interest in designing broadband wireless networks that can guarantee quality of service for traffic flows. However, a fundamental problem in these networks is that severe losses may occur due to the random fading characteristics of the wireless channel. Error control algorithms which compensate for these losses are required in order to achieve reasonable loss rates. In this paper, the performance of error control based on forward error correction (FEC) for MPEG-2 video transmission in an indoor wireless ATM LAN is studied. A random bit error model and a multipath fading model are used to investigate the effect of errors on video transport. Combined source and channel coding techniques that employ single-layer and scalable MPEG-2 coding to combat channel errors are compared. Simulation results indicate that FEC-based error control in combination with 2-layer video coding techniques can lead to acceptable quality for indoor wireless ATM video.Work performed while the author was at AT&T Bell Laboratories on a D.O.E. fellowship program.