DNA序列数据压缩技术综述

DNA序列数据压缩技术是根据DNA数据特点针对性地构造编码算法,以提升整体压缩效率的数据处理方法.本文介绍了DNA序列的基本概念及数据特点,DNA序列压缩算法的一般性描述,DNA序列的典型压缩算法,以及评估DNA序列压缩算法性能的重要指标,并对DNA序列压缩算法未来的发展趋势做了展望.     

雷达数据有损压缩综述

雷达信号的数据量非常庞大,如果不压缩进行存储或传输,会占用很大资源。文中介绍了雷达信号的特点,对常用的雷达数据压缩方法进行了分类,给出了评价指标。介绍了雷达有损压缩中较为典型的游程、单触发单元、离散余弦变换、小波分析等压缩算法,阐述了各算法的流程和关键技术,并结合评价指标进行了比较,提出了建议的压缩方法。文中将压缩流程扩展为去噪声和压缩2个部分,充分肯定了去噪在雷达数据压缩中的作用,得出了一些有意义的结论。     

Context-based lossless and near-lossless compression of EEG signals

We study compression techniques for electroencephalograph (EEG) signals. A variety of lossless compression techniques, including compress, gzip, bzip, shorten, and several predictive coding methods, are investigated and compared. The methods range from simple dictionary based approaches to more sophisticated context modeling techniques. It is seen that compression ratios obtained by lossless compression are limited even with sophisticated context based bias cancellation and activity based conditional coding. Though lossy compression can yield significantly higher compression ratios while potentially preserving diagnostic accuracy, it is not usually employed due to legal concerns. Hence, we investigate a near lossless compression technique that gives quantitative bounds on the errors introduced during compression. It is observed that such a technique gives significantly higher compression ratios (up to 3-bit/sample saving with less than 1% error). Compression results are reported for EEG's recorded under various clinical conditions     

立体图像压缩研究进展

简要回顾了立体图像压缩的研究进展。阐述了人类视觉系统与立体图像压缩密切相关的立体视觉特性，并且指出了立体图像压缩编解码器结构在有无失真情况下的最优性。简要描述了静止立体图像和立体图像序列压缩的研究进展。对将来的研究方向提出了一点建议。     

ECG data compression techniques-a unified approach

A broad spectrum of techniques for electrocardiogram (ECG) data compression have been proposed during the last three decades. Such techniques have been vital in reducing the digital ECG data volume for storage and transmission. These techniques are essential to a wide variety of applications ranging from diagnostic to ambulatory ECG's. Due to the diverse procedures that have been employed, comparison of ECG compression methods is a major problem. Present evaluation methods preclude any direct comparison among existing ECG compression techniques. The main purpose of this paper is to address this issue and to establish a unified view of ECG compression techniques. ECG data compression schemes are presented in two major groups: direct data compression and transformation methods. The direct data compression techniques are: ECG differential pulse code modulation and entropy coding, AZTEC, Turning-point, CORTES, Fan and SAPA algorithms, peak-picking, and cycle-to-cycle compression methods. The transformation methods briefly presented, include: Fourier, Walsh, and K-L transforms. The theoretical basis behind the direct ECG data compression schemes are presented and classified into three categories: tolerance-comparison compression, differential pulse code modulation (DPCM), and entropy coding methods. The paper concludes with the presentation of a framework for evaluation and comparison of ECG compression schemes.     

Putting data on a diet

The use of data compression to reduce bandwidth and reduce storage requirements is discussed. The merits of lossless versus lossy compression techniques, the latter offering far greater compression ratios, are considered. The limits of lossless compression are discussed, and a simple method for lossless compression, runlength encoding, is described, as are the more sophisticated Huffman codes, arithmetic coding, and the trie-based codes invented by A. Lempel and J. Ziv (1977, 1978), WAN applications as well as throughput and latency are briefly considered     

现代雷达信号处理的数字脉冲压缩方法

脉冲压缩技术是雷达信号处理的关键技术之一。文中主要从信号形式、优势和不足、应用场合等方面介绍线性调频、巴克码、多相码、非线性调频等几类常用脉冲压缩信号，提出在时域和频域实现数字脉冲压缩的统一数学模型，推荐了相应的工程实现方法。根据具体雷达的目的和不同类脉压信号的特性，设计最佳脉冲压缩滤波器是提高雷达脉冲压缩性能的关键。     

一种基于测试集分组的广义交替码

测试数据编码压缩是一类重要、经典的测试源划分（TRP）方法。本文提出了一种广义交替码，将FDR码、交替码都看作它的特例；又扩展了两步压缩方法，将原测试集划分成多组，每组采用不同的比值进行交替编码，综合了交替码与两步编码各自的优势，弥补了FDR码，交替码对某些电路测试集压缩的缺陷，得到了较好的压缩率。实验结果表明，与同类型的编码压缩方法相比，该方案具有更高的测试数据压缩率和较好的综合测试性能。     

Compression de données brutes et d’images de radar à synthèse d’ouverture

This paper draws a state of the art of synthetic aperture radar (sar) data compression. Both raw data and synthesized image compression have been investigated. Compression of radar raw signal and sar image are considered separately since those two cases are specific. Also, Radar raw/image compression remains different from optical image compression and has to be considered with specific strategies that are adapted to the context.     

Comparison of international standards for lossless still imagecompression

This overview focuses on a comparison of lossless compression capabilities of the international standard algorithms for still image compression known as MH, MR, MMR, JBIG, and JPEC. Where the algorithms have parameters to select, these parameters have been carefully set to achieve maximal compression. Compression variations due to differences in data are illustrated and scaling of these compression results with spatial resolution or amplitude precision are explored. These algorithms are also summarized in terms of the compression technology they utilize, with further references given for precise technical details and the specific international standards involved     

微波脉冲压缩研究

简要介绍了微波脉冲压缩技术的原理和实现方法,对储能切换法、能量倍增器法和功率二进压缩器法的实验原理进行了阐述。为了获得高功率的输出脉冲进行了L波段单路以及双路储能切换法脉冲压缩的实验,获得了GW级的输出脉冲。在此基础上对微波脉冲压缩的前景以及即将开展的工作进行了一个展望。     

最大误差可控的高光谱图像聚类压缩算法

针对原有基于奇异值分解的最大误差可控的高光谱图像压缩(EC-SVD)算法未充分利用图像光谱矢量间冗余的问题,该文将高光谱图像压缩与聚类结合,提出最大误差可控的高光谱图像聚类压缩算法。分析发现,图像的光谱矢量间相似度越高越有利于得到好的最终压缩效果。因此,算法首先使用K-均值聚类对高光谱图像像元按光谱矢量聚类,以提高同类光谱矢量间的相似度;其次,对每一类像元分别使用EC-SVD算法思想压缩以控制最大误差。论文证明了当高光谱图像的像元个数与波段数之比较大,且聚类类数不大于8时,聚类能够提高图像最终压缩比。最后,设计整体压缩实验仿真流程,并对实际高光谱图像进行数值仿真。结果表明,在相同参数条件下,该文算法比EC-SVD算法得到的压缩比和信噪比均有提高,最大压缩比提高了10% 左右。该文算法能够有效提高EC-SVD算法的图像压缩效果。     

基于离散余弦变换的图像压缩研究

图像压缩是数据压缩技术在数字图像上的应用,其目的是减少图像数据中的冗余信息,从而用更加高效的格式存储和传输数据。图像压缩可以是有损数据压缩也可以是无损数据压缩。这里所研究的是有损压缩技术,对于此类技术,变换编码是最常用的方法,如离散余弦变换（DCT）或者小波变换这样的傅里叶相关变换,然后进行量化和用熵编码法压缩。     

Efficient JPEG Encoding Using Bernoulli Shift Map for Secure Communication

To ensure confidentiality and efficient network bandwidth, digital data must be compressed and encrypted. In most communication systems, these two factors are critical for information processing. Image compression and encryption may result in lower restoration quality and performance. Secure-JPEG is an effort to create a compression and encryption technique for digital data. This approach is based on the JPEG compression standard, which is the most extensively used lossy compression scheme. It enhances the usual JPEG compression algorithm to encrypt data during compression. The Secure-JPEG approach encrypts the data while it is compressed, and it may be easily modified to offer near lossless compression. Lossless compression, on the other hand, has a lower compression ratio and is only useful in certain situations. The paper addresses the issue of insufficient security as a result of the usage of a simple random number generator that is not cryptographically safe. The enhanced security characteristics are provided via the Generalized Bernoulli Shift Map, which has a chaotic system with proven security. Several cryptographic tests are used to validate the algorithm's security, and the chaotic system's behavior is also examined.

     

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。     

Improved lossless compression of general data

New algorithms for lossless compression of general data are presented. They are based on adaptive lossless data compression (ALDC) but offer improved compression, typically 24% better for image data. The algorithms are simple to implement and are capable of high data throughput, whilst maintaining compatibility with legacy ALDC bit streams     

基于奇异值分解图像压缩算法的研究

提出了一种奇异值分解（SVD）的图像压缩算法,该算法通过对数字图像矩阵进行奇异值分解,将一幅图像转换成包含几个非零值的奇异值矩阵,实现图像压缩,便于图像的储存和传输。MATLAB仿真分析表明,矩阵的奇异值分解压缩方法具有较好的压缩性能,有效提高了压缩比。     

图像数据压缩的研究进展

本文介绍了图像数据压缩的常用技术及未来发展趋势。分为两个部分 :无损压缩和有损压缩。重点介绍了一些关键技术 ,如分形、小波变换和MPEG等。对于有关研究人员具有一定的参考价值     

优化NoC性能的存储和通信压缩

文中针对NoC体系结构,提出了两种数据压缩技术,被称为高速缓存压缩和网络接口控制(NIC)内的压缩.性能实测结果指示压缩能够使NoC设计在较低的网络延迟、较低的功耗和改进应用性能等方面获得优势.     

Optical pulse compression based on stationary rescaled pulse propagation in a comblike profiled fiber

In this paper, optical pulse compression using a comblike profiled fiber (CPF) is theoretically and experimentally studied, in which highly nonlinear fibers and single-mode fibers are alternately concatenated. Stationary rescaled pulse (SRP), is the main focus, which is a recently discovered nonlinear stationary pulse in CPF. The fundamental characteristics of SRP are investigated, and SRP propagation is applied to the design of the CPF pulse compressor. Using the proposed design method, the specifications of the CPF can easily be controlled, such as the compression ratio per step of the CPF or the pedestal of the output pulse. Two experimental results of pulse compression using the CPF based on the proposed design method are shown: 1) pulse compression with a large compression ratio per step of the CPF and 2) low-pedestal and wideband wavelength-tunable compression. A parametric noise-amplification phenomenon occurring in a compression process for an optical pulse sequence is also numerically analyzed.