无线视频传输中FEC与WZ联合抗误码算法研究

无线视频编码的低抗误性、无线信道带宽的有限性、无线视频业务的高需求决定了高鲁棒性的抗误算法必将成为无线视频通信的核心问题之一.基于FEC与WZ (Wyner-Ziv)两抗误工具的在不同误码率下抗误互补特性,提出了FEC与WZ联合抗误码方案.实验表明:该方案有效地综合了两者优点,提升了平均PSNR.     

运动补偿视频编码中DCT编码效率的研究

在视频序列图像编码中，运动补偿帧差图像的统计特性与静止自然图像有明显差别，对静止自然图像可以称为准最佳变换的离散余弦变换对帧差图像的编码效率有所下降。本文对这一问题进行了理论分析和实验验证，从而指出进一步提高视频序列图像编码效率的潜力所在。     

基于MPEG_2视频码流的错误分析

由于可变字长码（ ＶＬＣ） 在视频信号的高度压缩中会产生负面影响，因此全面分析了视频码流的结构和ＤＣ、ＡＣ 系数码字的单比特错误及可能给图像质量造成的影响， 这对于采取必要的手段来提高图像的质量有着十分重要的意义。     

BINet: A binary inpainting network for deep patch-based image compression

Recent deep learning models outperform standard lossy image compression codecs. However, applying these models on a patch-by-patch basis requires that each image patch be encoded and decoded independently. The influence from adjacent patches is therefore lost, leading to block artefacts at low bitrates. We propose the Binary Inpainting Network (BINet), an autoencoder framework which incorporates binary inpainting to reinstate interdependencies between adjacent patches, for improved patch-based compression of still images. When decoding a patch, BINet additionally uses the binarised encodings from surrounding patches to guide its reconstruction. In contrast to sequential inpainting methods where patches are decoded based on previous reconstructions, BINet operates directly on the binary codes of surrounding patches without access to the original or reconstructed image data. Encoding and decoding can therefore be performed in parallel. We demonstrate that BINet improves the compression quality of a competitive deep image codec across a range of compression levels.     

分形图象压缩编码的回顾与展望

介绍了分析图象压缩编码的历史和现状，以及几种方法的分形压缩技术，总结了近年来在分形图象压缩编码方法所取得的重要进展，并提出了一种新的序列图象分形编码的思路。     

Video object transmission by means of virtual reality based object extraction

This paper presents a new technique to extract objects from a real complex background so that a video sequence can be decomposed into a set of objects as required for object oriented video compression techniques. The proposed method is based on a background subtraction technique. However, instead of using a fixed background, the system relies on predicting one from a previously constructed virtual model of the environment. Thus, camera movements are allowed. These movements are estimated by means of a tracker device. We also present the virtual model construction technique for indoor environments. The method has been successfully tested for several different video sequences including capture errors, partially mapped virtual environments and camera positioning errors. Further work will focus on extending the virtual models not only to environment, but also to objects, and integrating the method in a MPEG4 standard compression system.     

X树图像编码

该文提出一种新的小波图像编码结构X树。X树是除根节点外其余的节点均为0的四叉树,它是零树的一种推广。在X树的基础上,文中提出了普通X树图像编码和嵌入式X树图像编码两种编码方案,实验表明该文提出的方案的编码效率明显高于零树(EZW)和栈-游程(Stack-run)编码。     

视频压缩国际标准的发展概况

本文概述了视频压缩国际标准的发展。ＪＰＥＧ静态图像压缩标准和有关可视电话与会议电视的Ｈ．２６１是视频压缩的基础；Ｈ．２６３视频压缩标准则将可视技术扩展到低速率通信网上；ＭＰＥＧ标准间主要的高速视频压缩技术，专家组在制订ＭＰＥＧ－１、ＭＰＥＧ－２标准后，把目标放在制订面向对象的ＭＰＥＧ－４标准，该标准将使视频压缩技术走向新的里程。     

Exact image subband decomposition/reconstruction by DCT

In a recent paper an image decomposition/reconstruction subband coding scheme free of aliasing and boundary errors has been proposed. Ideal filters have been used and implemented with DFT. A few additional data are necessary to perform the exact reconstruction. We show here that the use of DCT to implement a similar filtering process avoids the use of this additional data. Practically, the computation load does not change.     

An entropy minimization histogram mergence scheme and its application in image compression

In this paper, we propose an entropy minimization histogram mergence (EMHM) scheme that can significantly reduce the number of grayscales with nonzero pixel populations (GSNPP) without visible loss to image quality. We proved in theory that the entropy of an image is reduced after histogram mergence and that the reduction in entropy is maximized using our EMHM. The reduction in image entropy is good for entropy encoding considering that the minimum average code word length per source symbol is the entropy of the source signal according to Shannon’s first theorem. Extensive experimental results show that our EMHM can significantly reduce the code length of entropy coding, such as Huffman, Shannon, and arithmetic coding, by over 20% while preserving the image subjective and objective quality very well. Moreover, the performance of some classic lossy image compression techniques, such as the Joint Photographic Experts Group (JPEG), JPEG2000, and Better Portable Graphics (BPG), can be improved by preprocessing images using our EMHM.     

A fast progressive image transmission scheme using block truncation coding by pattern fitting

In this paper, we have proposed a novel progressive image transmission scheme. In the present method, the concept of the BTC-PF is used for faster decoding. Here, images are decomposed into a number of blocks based on smoothness criterion. The smooth blocks are encoded by block means and the others are by BTC-PF method. To encode a block by BTC-PF method, the codebook is organized like a full search progressive transmission tree which helps greatly in efficient progressive transmission. The present method provides good image quality at low bit-rate and faster decoding compared to other spatial domain progressive transmission methods. We extend this method for color images also. In color image coding, each color plane is encoded separately and then the encoded information of the planes are transmitted in interleaving manner to obtain color images right from the early stages.     

视频编码比特率和重建图像显示的清晰度

以数字标准清晰度电视（ＳＤＴＶ）规定的范围为重点,讨论视频编码比特率与重建图像显示清晰度的关系。其中着重指出：在采用ＭＰＥＧ－１／２－进行视频压缩编码而且压缩编码的算法确定时,应该依据视频的比特率的大小来选取恰当的视频格式,便于猁所期望的重建图像显示的清晰度。     

Quality measurement and use of pre-processing in image compression

Traditional quality measures for image coding, such as the peak signal-to-noise ratio, assume that the preservation of the original image is the desired goal. However, pre-processing images prior to encoding, designed to remove noise or unimportant detail, can improve the overall performance of an image coder. Objective image quality metrics obtained from the difference between the original and coded images cannot properly assess this improved performance. This paper proposes a new methodology for quality metrics that differentially weighs the changes in the image due to pre-processing and encoding. These new quality measures establish the value of pre-processing for image coding and quantitatively determine the performance improvement that can be thus achieved by JPEG and wavelet coders.     

面向实时视频压缩的单片硬件结构

从视频信号的特征出发，简要说明了实时视频压缩的常用算法及其国际标准。通过系统地分析了视频压缩算法中内在的模块特性和并行特性，结合数字信号处理领域中具有并行实现机制的典型硬件结构，得出了可用于实时视频压缩的两种单片硬件结构模型。     

无线网络面向视频传输优化的机会网络编码机制

现有的无线网络编码机制大多没有考虑无线链路质量对于视频传输的影响,导致视频质量降低。该文针对这一问题,提出面向视频传输优化的机会网络编码(O2NC)机制。该机制结合网络编码和机会路由技术,根据传输路径收益和视频数据的重要程度计算候选节点集合;同时,考虑视频数据包编码比重和重要程度等参数,评估编码包综合效用,选取转发效用值最大的视频编码组合。仿真结果表明,与典型的网络编码协议相比,O2NC机制能够显著提高视频序列的可解码帧率和峰值信噪比(PSNR)。     

无线视频通讯中的自适应差错非均匀保护方案

针对划分了重要级别的H-264视频编码数据提出五种可能的不平等保护策略，通过测试和比较，最终提出一种高误码率下无线视频可靠性传输的全局最优不平等保护策略。仿真实验表明，在无线网络带宽和信道误码率不同的情况下，这种最优策略都能使接收端信源解码后的视频图像峰值信噪比(PSNR)既稳定又具鲁棒性。     

雷达视频信号压缩编码的研究

现代新体制雷达普遍采用脉压技术使视频回波变窄,因而对雷达图像压缩编码提出了更高的要求。在对雷达图像进行比较深入的分析后.提出了一种新的雷达视频信号压缩编码算法,进行了电路设计及仿真,并分析了该方法的优点。给出了压缩性能。     

基于帧间去相关的超光谱图像压缩方法

针对超光谱图像的特点和硬件实现的实际需要,提出了一种基于小波变换的前向预测帧间去相关超光谱图像压缩算法。通过图像匹配和帧间去相关,消除超光谱图像帧间的冗余,对残差图像的压缩采用基于小波变换的快速位平面结合自适应算术编码的压缩算法,按照率失真准则控制输出码流,实现了对超光谱图像的高保真压缩。通过实验证明了该方案的有效性,基于小波变换的快速位平面结合自适应算术编码的压缩算法速度优于SPIHT,而且易于硬件实现。     

HEVC intra mode selection based on Rate Distortion (RD) cost and Sum of Absolute Difference (SAD)

High Efficiency Video Coding (HEVC) encoder provides higher compression efficiency by offering 35 intra modes. However, the encoding complexity is increased due to more modes are involved in the decision process. Therefore, it is desired to build a fast intra prediction algorithm that is practical for real time application. In this paper, a quadratic approach for reducing intra coding complexity is proposed. Firstly, the relationship between the RD-cost and the SAD is investigated. Secondly, a model is proposed to estimate the RD-cost of all 35 intra modes using the quadratic relation, thus avoiding the computation of entropy coding, Hadamard cost, distortion, and transform. Experimental results demonstrate that the average time saving of the proposed approach is 31–38%, while the BD-Bit Rate increment is only 0.62–1.37%, respectively.