压缩域多媒体数据处理技术研究

多媒体数据压缩技术是多媒体、网络通讯以及计算机等应用领域的一项关键技术。多媒体数据经过压缩后再进行存储或通过网络进行传输,这已经逐渐成为多媒体应用中的标准模式;同时,多媒体应用中所涉及到的各种媒体数据,如图象、视频和音频数据,往往需要进行各种灵活的操作与处理,因此,压缩域多媒体数据直接处理技术成为一项很有意义的研究领域。文中首先就压缩数据处理的基本概念进行讨论,然后集中分析了这一研究领域的重要研究     

基于JPEG的远程控制系统设计

介绍了远程控制的特征及基本思想,分析了远程控制遇到的障碍,比较了几种常用的解决方案及其不足.在此基础上,提出了基于拷屏和JPEG标准压缩的解决方案,该方案有较好的实时性和较低的复杂度,可广泛应用于远程教育、远程技术支持等网络多媒体应用领域.     

DCT域图象处理和特征提取技术

现今 ,大量的图象与视频信息都是以压缩数据格式进行存储和传输的 .DCT(Discrete Cosine Transform离散余弦变换 )是目前应用最为广泛的多媒体数据压缩技术之一 .直接在 DCT域实现如视频编辑、特征提取等传统空域处理技术 ,能够避免繁琐的压缩数据编、解码操作 ,减少处理时间和数据处理量 ,节省内存空间 .这一技术对于高速海量的数据处理场合 ,如 Internet信息检索、视频编辑和检索、远程监视图象的理解等 ,是很有吸引力的 ,因此其是近年来国际上有关领域的研究热点之一 .本文对近年来文献中所见的 DCT域图象处理和特征提取技术进行了回顾和综述 ,并在此基础上对其发展方向进行了探讨     

计算机多媒体音像压缩技术的研究及应用前景探析

计算机多媒体技术功能丰富,包括音频、视频、图像、文字、动画等。在互联网和通信技术迅速发展的今天,计算机多媒体音像也随之发展,很多行业如医疗,书籍,金融,通讯,咨询服务等等都在其影响下发生了巨大变化。然而,计算机多媒体音像数据压缩技术的发展,是互联网与通信技术得以深入发展的关键所在。由于音频、视频、图像信号中冗余信息的存在,为数据压缩在多媒体音像技术中的应用提供平台。数据压缩技术包括无损压缩和有损压缩,这些压缩技术又有其各自的标准。本文对计算机多媒体音像压缩技术进行了研究,并对其应用前景进行了探讨分析。     

基于H.264的甚低码率实时视频传输

本文采用视频数据压缩技术来降低数据量,研究开发了一套基于H.264的甚低码率视频传输系统。该系统采用了Windows套接字网络编程API,使用了UDP通信方式,用VC++实现了视频数据的采集、压缩、传输和再现。     

多媒体压缩技术

多媒体压缩是多媒体信息中的重要技术问题。本文针对当前的各种压缩技术,详细叙述了压缩的方式和方法,分析了各种压缩的特点和应用领域,为研究和使用多媒体数据压缩技术提供一定的参考。     

多媒体压缩技术综述

数据压缩技术是多媒体最重要的关键技术。综述了多媒体中视频和音频压缩技术，并对它们的研究重点和发展方向进行了展望     

多媒体数据压缩标准——MPEG系列

随着各种多媒体数据压缩标准的制定及计算机硬件、网络技术的发展,多媒体信息的应用呈现出爆炸式的增长.为了适应用户终端的多样性及网络自身的传输特性,20 世纪90年代后期,一些国际标准化组织制定了几个多媒体数据压缩标准,并且获得了成功的应用,其中最主要的是MPEG系列.在此主要从视频的编码原理,视频数据组织结构和应用领域等方面对MPEG-1、MPEG-2、MPEG -4和MPEG-7做了一些介绍.     

《多媒体计算机实用技术》讲座(九)

由于一幅图象所需要占用的存储空间非常大,为了让您的磁盘存放更多的图象,也为了缩短在网络上传输图象的时间,就非常需要把图象数据进行压缩。图象数据压缩技术是一门有几十历史的科学技术,尤其是数字图象的数据压缩技术一直是众多科学技术人员奋斗的领域,进入20世纪80年代之后,数字图象数据压缩技术有很大突破,进入90年代之后在计算机工业中得到广泛应用,新技术、新产品不断涌现。     

基于PSTN的远程多媒体监控系统

基于PSTN网的远程多媒体监控技术,其关键是针对监控应用要求,在保证一定的图象和语音质量的同时,对图象与语音以尽量高的压缩率进行压缩,以及对图象与语音压缩进行实时处理,在所分析的基于PSTN的远程多媒体监控系统中,图像和语音压缩处理是采用H．263和G．732．1协议,首先介绍了该系统组成结构;然后在简要介绍基于H．263和G．732。1协议的图像与语音压缩算法的基础上,进一步讨论了针对远程多媒体监控的应用要求,基于图象与语音压缩的若干考虑,着重讨论和介绍了该系统的关键组成部分,即多媒体远程监控终端机的设计与实现,提出了基于高速DSP技术的图象与语音压缩实时处理的关键技术及所采取的措施,并对系统的主要性能进行了概略的介绍。     

一种基于分块采集和压缩技术的屏幕共享方案

在深入研究现有的屏幕共享方法的基础上,在实际的远程教学系统的项目实践过程中提供了一种基于分块采集和压缩技术的解决方案。该方案主要利用分块采集和数据压缩技术来实现异地屏幕显示图像的共享,即首先使用划分的思想把屏幕分成一些固定的块,然后分块采集屏幕图像,对采集的图像进行分析,从而决定采用哪一种技术进行压缩,然后打包传输。针对图像发生变化的块数来决定采用何种压缩技术,主要有LZW和RLE数据压缩技术。实验证明,该方案不仅可以获得很好的压缩率,并且具有较好的实时性和较低的编码复杂度,因此,应用前景广泛。     

多算法融合比较的图像文件索引压缩

近年来由于科技的发展和互联网的兴起,图像资料已被广泛地应用在网络上,而图像压缩不但可以节省图像资料占用的内存空间,并且可以加速其传输速度,因此图像压缩技术目前被广泛应用于医学、手机、数据传输、多媒体影音、互联网络等。这里主要是针对无失真的图像压缩技术,先将原始图像转成256色的GIF格式,然后再建立一个索引矩阵,矩阵中元素是由原色RGB信息对应所组成,利用索引矩阵排序法并配合编码簿,再加上配合LZW、CALIC、JPEG2000、JPEG-LS等不同压缩算法,来比较压缩的效果。     

A data embedding scheme for color images based on genetic algorithm and absolute moment block truncation coding

Recently, embedding a large amount of secret data into gray-level and color images with low distortion has become an important research issue in steganography. In this paper, we propose a data embedding scheme by using a well-known genetic algorithm, block truncation code and modification direction techniques to embed secret data into compression codes of color images to expand the variety of cover media. In the scheme, the common bitmap generation procedure of GA-AMBTC has been modified to speed up the hiding procedure. Two embedding strategies are proposed to hide secret data into the common bitmap and the quantization values in each block of the cover image. Experimental results confirm that the proposed scheme can provide high data capacity with acceptable image quality of the stego-images. Moreover, the compression ratio of the scheme is exactly the same as that of GA-AMBTC so that attackers cannot detect any trace of hidden data from the size of the modified compressed result.     

基于整数小波变换和子带比特平面编码的图象压缩算法

在分析图象整数小波变换的基础上 ,提出了基于子带比特平面编码的压缩算法 .该算法将整数小波系数按子带分为若干比特平面 ,称之为子带比特平面 ,并采用简单高效的率失真优化算法确定子带比特平面的编码顺序 ,且这一顺序与图象无关 .按此顺序对子带比特平面进行自适应 MQ算术编码 ,便得到嵌入式压缩码流 .该算法可以从无损到有损 ,以任意倍率或质量进行图象压缩 ,压缩效率达到了浮点 EZW算法和 JPEG2 0 0 0整数小波编码方案的水平 ,而速度远快于这两者的速度 .该算法还具有复杂度低 ,占用内存少的优点 .     

Better bitmap performance with Roaring bitmaps

Bitmap indexes are commonly used in databases and search engines. By exploiting bit‐level parallelism, they can significantly accelerate queries. However, they can use much memory, and thus, we might prefer compressed bitmap indexes. Following Oracle's lead, bitmaps are often compressed using run‐length encoding (RLE). Building on prior work, we introduce the Roaring compressed bitmap format: it uses packed arrays for compression instead of RLE. We compare it to two high‐performance RLE‐based bitmap encoding techniques: Word Aligned Hybrid compression scheme and Compressed ‘n’ Composable Integer Set. On synthetic and real data, we find that Roaring bitmaps (1) often compress significantly better (e.g., 2×) and (2) are faster than the compressed alternatives (up to 900× faster for intersections). Our results challenge the view that RLE‐based bitmap compression is best. Copyright © 2015 John Wiley & Sons, Ltd.     

Visual C++在动态显示过程屏幕闪烁的消除

采用 GDI位图及内存设备环境改进屏幕显示 ,通过创建内存设备环境以及与显示兼容的位图 ,先将图形绘制在与内存设备环境兼容的位图中 ,这样显示时就只需将图形从位图中复制到显示器屏幕上 ,缩短了显示图形所用的时间 ,并且不必擦除背景 ,实现了无闪烁的连续过程     

JPEG图像篡改的盲检测技术

数字图像被动认证技术是一门不依赖数字水印或者签名等图像先验知识而对图像来源和内容真实性进行认证的新兴技术,JPEG图像篡改的盲检测已成为当前被动认证的研究热点。详细分析了三种基于JPEG压缩的盲检测算法：JPEG压缩历史检测和量化表的估计,块效应不一致性的篡改区域检测,JPEG二次压缩的检测,系统阐明了现有算法的基本特征和优缺点,最后展望了未来的研究方向。     

A YC‐separation‐type projector: High dynamic range with double modulation

Abstract— An experimental projector that features double modulation to obtain high‐resolution (4096 × 2160 pixels) and high‐dynamic‐range images has been developed. Although a conventional projector contains three modulators for red, green, and blue and outputs light after combining the modulated light from these three sources, our projector has an additional modulator for luminance that modulates the combined RGB modulated light. It can display high‐resolution color images by combining three low‐resolution panels for chrominance modulation and one high‐resolution panel for luminance modulation. In addition, the dynamic range is dramatically improved because the double‐modulation scheme minimizes black levels in projected images. The projector demonstrates an extremely high dynamic range of 1.1 million to 1 and 10‐bit tone reproduction.     

Paired Subimage Matching Watermarking Method on Ordered Dither Images and Its High-Quality Progressive Coding

In this paper, we present two novel robust methods for embedding watermarks into dithered halftone images. The first method is named paired subimage matching ordered dithering (PSMOD), of which the decoder is provided with a priori information of the original watermark, and the corresponding application is copyright protection. The other method, blind paired subimage matching ordered dithering (BPSMOD), does not require the knowledge of the original watermark, and the main application is secret communication. Both methods utilize the bit and sub-subimage interleaving preprocesses. The experiments show that both techniques are sufficiently robust to guard against the cropping, tampering, and print-and-scan degradation processes, in either B/W or color dithered images. Both techniques are also sufficiently flexible for various levels of embedded capacities. Furthermore, a novel progressive coding scheme is also presented in this paper for the efficient display of dithered images. After the preprocessing of bit-interleaving, this algorithm utilizes the characteristic of reordered image to determine the transmitting order and then progressively reconstructs the dithered image. Moreover, the dithered images are further compressed by lossy and lossless procedures. The experimental results demonstrate high-quality reconstructions while maintaining low transmitted bit rates.     

An HVS based adaptive quantization scheme for the compression of color images

In this paper a Human Visual System based adaptive quantization scheme is proposed. The proposed algorithm supports perceptually lossless as well as lossy compression. The algorithm uses a transform based compression approach using the wavelet transform, and has incorporated vision models for the compression of both luminance and chrominance components. The major strength of the coder is the incorporation of the vision model for the chrominance components and the optimum way in which the scales are distributed among the luminance and chrominance components to achieve higher compression ratios. The perceptual model developed for the color components gives flexibility for giving more compression for the color components without causing any color degradations. For each image the visual thresholds are evaluated and an optimum bit allocation is done in such a way that the quantization error is always less than the visual distortion for the given rate. To validate the strength of the proposed algorithm, the perceptual quality of the images reconstructed using the proposed coder is compared with the images reconstructed with JPEG2000 standard coder, for the same compression. To evaluate the perceptual quality of the compressed images latest perceptual quality matrices such as Structural Similarity Index, Visual Information Fidelity and Visual Signal-to-Noise Ratio are used. The results obtained reveal that the proposed structure gives excellent improvement in perceptual quality compared to the existing schemes, for both lossy as well as lossless compression. These advantages make the proposed algorithm a good candidate for replacing the quantizer stage of the current image compression standards.