基于能量守恒全零DCT系数块的预先判别算法

针对全零DCT系数块,为避免对其进行变换和量化操作以减少编码器的运算量,从DCT公式、量化和能量守恒出发,在分析现有判别法对全零DCT系数块的误判与漏判的基础上,提出了一种预先判断全零DCT系数块的新方法,可应用于基于块的视频编码器中.同时,结合H.264整数变换和量化的特点对该算法进行了改进和仿真实验.实验结果表明,新提出的算法在保持PSNR不变的情况下,较现有典型方案有高出达32%的检出率,因而可更大幅度地降低DCT变换量化模块的计算复杂度.     

Reversible Data Hiding Based on Run-Level Coding in H.264/AVC Video Streams

This paper presents a reversible data hiding (RDH) method, which is designed by combining histogram modification (HM) with run-level coding in H.264/advanced video coding (AVC). In this scheme, the run-level is changed for embedding data into H.264/AVC video sequences. In order to guarantee the reversibility of the proposed scheme, the last nonzero quantized discrete cosine transform (DCT) coefficients in embeddable 4×4 blocks are shifted by the technology of histogram modification. The proposed scheme is realized after quantization and before entropy coding of H.264/AVC compression standard. Therefore, the embedded information can be correctly extracted at the decoding side. Peak-signal-noise-to-ratio (PSNR) and Structure similarity index (SSIM), embedding payload and bit-rate variation are exploited to measure the performance of the proposed scheme. Experimental results have shown that the proposed scheme leads to less SSIM variation and bit-rate increase.     

基于YCoCg-R颜色空间与离散余弦变换的自适应彩色图像水印算法

目的为了解决当前彩色图像水印技术的水印容量和不可感知性不佳等问题,设计基于YC_oC_g-R颜色空间和离散余弦变换的自适应图像水印算法。方法首先,将载体图像从RGB空间转换到YC_oC_g-R空间,计算Y,C_o,C_g这3个颜色分量;随后,引入离散余弦变换DCT对Y分量进行处理,获取相应的DCT系数;引入模糊聚类分析,将DCT低频系数视为局部特征,利用SVM机制对DCT低频系数进行训练分类,确定出适合嵌入水印的DCT系数;设计水印嵌入机制,将水印数据隐藏到合适的DCT低频系数中;借助可逆DCT方法,将Y分量从频域变换到空域;联合初始的C_o与C_g分量,将其变换到RGB空间,输出水印图像;最后,通过相应的水印提取方法,复原初始水印信息。结果测试数据表明,与当前水印方法相比,所提技术具有更高的不可感知性与水印容量,其水印图像的PSNR值为43.67 dB,且其允许的水印容量可超过1 bits,在多种攻击下,复原水印的质量更高,相关系数NC均超过了0.92。结论所提技术能够较好地将水印信息隐藏在载体图像中,具有较高的鲁棒性和安全性。     

一种适用于随机检测的稳健性视频水印方法

随机检测是视频水印需要解决的关键问题之一,目前的视频水印缺乏有效的随机检测技术.对此,文中提出了一种适用于随机检测的稳健性视频水印方法.该方法先将水印信号进行BCH编码并按密钥置换,然后将编码后的数据和同步码依次嵌入到DCT块的候选中频系数中,并通过同步码来实现水印的快速随机检测.实验表明,该方法具有良好的抗噪声、视频压缩编码和裁剪性,并能实现了水印的随机检测和水印信息的字节对齐.     

H.264/AVC baseline profile to MPEG‐4 visual simple profile transcoding to reduce the spatial resolution

In this study, we propose a heterogeneous transcoding method of converting an H.264/Advanced video coding (AVC) Baseline profile (BP) video bitstream into an MPEG‐4 Visual simple profile (VSP) video bitstream. The proposed method reduces the spatial resolution for mobile terminals, which support only low resolution video bitstreams. When the H.264/AVC BP video bitstream is transformed into the MPEG‐4 VSP video bitstream, the conversions between the H.264/AVC BP block types and the MPEG‐4 VSP block types are performed by analyzing the macroblocks (MBs) conversion probability and calculating the difference values of motion vector. The proposed transcoding method runs on average 5.5 times faster than the cascaded transcoding methods, for a degradation of the PSNR (peak‐signal‐to ratio) of less than 0.5 dB. © 2006 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 16, 24–33, 2006     

Research on adaptive scanning and quantisation for 3D DCT video coding

Abstract

Nowadays, a well-established video coding method is based on the block-matching algorithm that is in the core of all MPEG and H.26x standards. However, this method involves motion estimation and compensation; thus the computational complexity is high. However, the video coding based on three-dimensional discrete cosine transform (3D DCT) is a potential method, and the scanning order and quantisation of 3D DCT coefficients play a crucial role in coding effect. So, the statistical performances of 3D DCT are studied in this paper, and then adaptive scanning order and quantisation of 3D coefficients are proposed. The theoretical analysis and experiment results show significant improvement in performance over previously reported methods.     

A no reference quality metric to measure the blocking artefacts for video sequences

The need to measure video quality arises in the development of video equipment and in the delivery and storage of video and image information. In this paper, we propose a new perceptually significant video quality metric to estimate the effect of block coding for standards H.264 AVC and MPEG2. Our method operates in the spatial domain and does not require a high complexity of computation. We evaluate the performance of the proposed method by using three sequences CIF ‘common intermediate file’ with different compression rate. We compare it with Suthaharan’s and MSU’s techniques by using ‘LIVE’ and ‘IVP’ databases. Results indicate that the proposed method outperforms Suthaharan’s and MSU techniques in H264 coder. They also indicate that our method is more effective than MSU’s and Suthaharan’s techniques for the H.264 AVC standards with the Spearman Rank Order Correlation Coefficient.     

Fast intra prediction mode decision for H.264/AVC video coding

Abstract

Intra coding is used for reducing the spatial redundancy in video coding. H.264 supports several macroblocks of predictions for intra coding such as luma block four 16×16 modes, nine 4×4 modes and chroma block four modes, which significantly improve intra coding efficiency, but increase the encoding complexity. In order to select the best mode, we need to calculate the cost of the various modes. In this paper, a fast intra prediction mode decision for H.264/AVC video coding is proposed. Based on Laplacian, this intra prediction mode decision detects edges and selects the best mode for the block. This mode decision can shorten the time to reduce the encoding time. The experimental results show that the proposed algorithm achieves an encoding time saving of 70% on average.     

支持隔行扫描的两步DCT域视频水印算法

提出了一种在隔行扫描MPEG-2视频流中嵌入DCT域水印的算法。该算法对MPEG-2中DCT变换按帧和按场进行的两种情况采用不同的扩频码进行嵌入和检测,使水印的检测基本不受DCT方式变化的影响,从而能够抵抗各种重编码攻击,同时也保持了良好的实时性。还采用了两步算法,即除水印数据外还同时嵌入了少量同步信息,这样既可定期更新用于水印数据的扩频码,从而提高算法的安全性与灵活性,同时在存在帧插入／删除等攻击时又不会因失去同步而导致检测失败。     

一种基于混沌映射的鲁棒性图形水印算法

提出了一种基于混沌映射的DCT域数字图像水印算法。将含有特定信息的二值序列作为原始水印,利用混沌密码对其进行加密,并在嵌入时再利用混沌映射将水印信息嵌入原始图像的DCT域,使得水印方案具有双重安全性。由于在水印检测时不需要原始图像的参与,该算法实现了水印的盲检测。实验结果表明,用该算法嵌入的水印信息具有不可见性,其对常见的图像处理如JPEG压缩、噪声、滤波以及剪切等具有良好的鲁棒性。     

基于掩蔽效应和抖动调制的盲水印方案

通过对信号处理领域抖动调制原理的分析,并结合人类视觉系统的掩蔽效应,提出了一个DCT 域盲水印模型。在MATLAB 仿真环境中,针对二值图像水印,实现了水印的预处理、嵌入、提取以及F 范数下水印检测。在水印嵌入过程中,通过自动调节量化步长改善了水印的透明性,水印检测时无需原始宿主图像,实现了盲检测,而且省略了反余弦变换过程,降低了算法复杂度。仿真实验表明,水印算法在JPEG 高强度压缩、剪切、各种噪声叠加以及多重水印等攻击下具有高鲁棒性。算法思想可应用于数字版权保护以及隐秘通讯等领域。     

Optimal weighed Holoentropy for video compression: an advanced HEVC

ABSTRACT

In recent times, the applications of multimedia are rising in a greedy mode and hence the amount of video transactions is also increasing exponentially. This has shouted great demands on effective models on video encoding and also for reducing the transmission channel congestion. This research work introduces a managing technique termed weighted encoding for High-Efficiency Video Coding (HEVC). HEVC, also termed as MPEG-H Part 2 and H.265 is a video compression standard that is widely utilized AVC (H.264 or MPEG-4 Part 10). When compared to AVC, HEVC grants double the ratio of data compression at a similar level of quality of the video or considerably enhanced video quality at a similar bit rate. This work intends to optimize the weight that adopted in HEVC for encoding. For this, this paper proposes a new Iterative based propagation update in the water wave Optimization Algorithm (IPU-WWO), which is the improved form of Water wave Optimization (WWO). The performance of proposed IPU-WWO is compared over other conventional methods like Artificial Bee Colony (ABC), Firefly (FF), Particle Swarm Optimization (PSO) and Genetic Algorithm (GA) with respect to Peak Signal to Noise Ratio (PSNR). By doing the encoding process, it minimizes the video size with perceptually better quality video or PSNR.     

Novel fast block motion estimation using diamond‐arc‐hexagon search patterns

Abstract

This work presents a novel block motion estimation (ME) approach, diamond‐arc‐hexagon search (DAHS), which uses diamond, arc, and hexagon search patterns to accomplish the fast searching process. According to the characteristic of the center‐based motion vector distribution for the real‐world video sequence, DAHS employs a small diamond pattern extended hexagon search to refine the central area search. Furthermore for estimation in large motion situations, the strategy of the large diamond‐to‐arc search can preserve good performance. Experimental results indicate that DAHS is suitable for both (quasi‐) stationary and large motion searches. DAHS outperforms the efficient three‐step (E3SS) and hexagon‐based search (HEXBS) in prediction quality, and improves the searching speed about 9% compared to E3SS. The proposed algorithm was tested using several sequences and delivered excellent performance in search speed and prediction of video quality. The DAHS can be applied to real‐time video processes, such as H.264/MPEG‐4 advanced video coding (AVC) and scalable video coding (SVC).     

A MV-Based Steganographic Algorithm for H.264/AVC without Distortion

H.264/AVC video is one of the most popular multimedia and has been widely used as the carriers of video steganography. In this paper, a novel motion vector (MV) based steganographic algorithm is proposed for the H.264/AVC compressed video without distortion. Four modules are introduced to eliminate the distortion caused by the modifications of motion vectors and guarantee the security of the algorithm. In the embedding block, the motion vector space encoding is used to embed a (2n+1)-ary notational number into an n-dimension vector composed of motion vectors generated from the selection block. Scrambling is adopted to disturb the order of steganographic carriers to improve the randomness of the carrier before the operation of embedding. The re-motion compensation (re-MC) block will re-construct the macroblock (MB) whose motion vectors have been modified by embedding block. System block plays the role of the generator for chaotic sequences and encryptor for secret data. Experimental results demonstrate that our proposed algorithm can achieve high embedding capacity without stego video visual quality distortion, it also presents good undetectability for existing MV-based steganalysis feature. Performance comparisons with other existing algorithms are provided to demonstrate the superiority of the proposed algorithm.     

一种基于双边假设检验的Contourlet域乘性水印盲检测算法

为解决Contourlet变换域中乘性水印的检测问题,根据广义高斯分布描述图像Contourlet变换高频方向子带系数的统计分布特征,在服从广义高斯分布的系数中,将水印的检测问题转化为了具有未知参数的确定性伪随机序列的检测问题,利用双边假设检验推导出了适用于Contourlet域乘性水印的盲检测器。实验表明,该盲检测器的判决准,对任何嵌入强度均有效,并且可以自适应地确定检测阈值。     

Digital watermarking based on fractal image coding

Abstract

With advances in computer network and multimedia technology, digital media are rapidly proliferating, and thus the issue of copyright protection for electronic publishing is receiving great attention. To achieve the goal of copyright protection, the digital watermarks are used to identify the owner of a certain image, so as to prevent illegal copying. Digital watermarking is the technique that embeds an invisible signal including owner identification and copy control information into multimedia data such as audio, video, and images. A new digital watermark approach based on fractal image coding is proposed in this paper. We present a way to use the fractal code as a means of embedding a watermark into image. The proposed approach has been shown to be resistant to general attacks, like StirMark. Moreover, someone who owns the decryption key can simply extract the digital watermark from the watermarked image without resorting to the original image.     

An adaptive compressed MPEG-2 video watermarking scheme

Digital watermarking is becoming more and more important for protecting the authenticity of multimedia objects as they become easier to copy, exchange, and modify. Several watermarking schemes have been proposed in recent years, but most of them deal with still images, only some being extended over to the temporal domain for video watermarking. But again most of those approaches are applied to uncompressed video processing domain. In the subject paper, a new compressed video watermarking procedure is proposed. The developed method embeds several binary images, decomposed from a single watermark image, into different scenes of a video sequence. The spatial spread spectrum watermark is embedded directly into the compressed bit streams by modifying discrete cosine transform (DCT) coefficients. In order to embed the watermark with minimum loss in image fidelity, a visual mask based on local image characteristics is incorporated. Extensive experimental simulations demonstrate that the proposed watermarking scheme is substantially more effective and robust against spatial attacks such as scaling, rotation, frame averaging, and filtering, besides temporal attacks like frame dropping and temporal shifting.     

脊波变换域盲数字水印方案

鲁棒性是数字水印最基本的要求之一,水印嵌入的位置和强度直接影响到水印的鲁棒性.本文提出了一种新的基于离散脊波变换(DRT)的盲水印算法,利用脊波变换对线状奇异性的稀疏表示特性,找出图像中视觉重要信息,并将水印嵌入其中,提高了水印的鲁棒性.根据图像局域脊波系数来选取水印嵌入强度,保证了水印的不可见性.水印提取不借助于原始图像,能实现盲提取.在强烈攻击的情况下,实验结果表明,此方法对JPEG压缩、滤波、噪声、裁剪等攻击具有很好的鲁棒性.     

Highly efficient CAVLC encoder for MPEG-4 AVC/H.264

In dealing with high-resolution video information, encoding (or decoding) with an efficient context-based adaptive variable length code (CAVLC) encoder is important. A highly efficient CAVLC encoder is proposed for video coding application of MPEG-4 AVC/H.264. The main concept is to use block-based pipelining to speed up encoding efficiency and reduce the pipeline storage elements by using the associated input buffer. We also use zero-block detection to speed up encoding efficiency and eliminate the same codeword from all the tables to save the hardware cost. Simulation results show that our design can meet the real-time processing for 1920 times 1088 resolution with lower operation frequency. We also accomplish the higher encoding throughput with a more complete CAVLC design than others. The proposed design has been implemented and synthesised with TSMC 0.18 mum standard cell library. The synthesis result indicates that the gate count is 12 125 with the clock constraint of 125 MHz.     

小波变换域互补鲁棒性视频多水印算法

数字水印是解决数字视频版权保护问题的一种有效技术手段.为了能同时抵抗几何攻击和时间域去同步攻击,本文提出了一种新的互补视频水印方案.根据视频序列的特点,沿时间轴嵌入第一个鲁棒水印,用以抵抗各种几何攻击;第二个鲁棒水印是借助静止图像水印技术在每一帧中嵌入,用以抵抗时间域去同步攻击.整个水印系统能互补地抵抗各种攻击形式,从而增强了算法的整体鲁棒性.水印的提取不需要原始视频信号.实验结果表明,该水印算法对帧丢失、帧插入等时间域去同步攻击以及几何攻击具有良好的鲁棒性.