中文摘要

现代社会已经进入了一个高速信息化时代｡信息化的发展带动了计算机与多媒体技术的不断发展,处于对图像通信与图像储存的要求,人们期望有一个统一而高效图像压缩标准的出现｡静止图像作为计算机上经常使用的一种图像形式同时也是动态图像的基础,其压缩技术无疑是一项相当重要的｡JPEG标准就是在这种情况下应运而生的｡JPEG压缩技术十分先进,它用有损压缩方式去除冗余的图像数据,在获得极高的压缩率的同时能展现十分丰富生动的图像,且 JPEG是一种很灵活的格式,具有调节图像质量的功能,允许用不同的压缩比例对文件进行压缩,支持多种压缩级别,压缩比越大,品质就越低;相反地,压缩比越小,品质就越好.

图像数据压缩不仅是必要的,而且也是可能的,因为图像数据间有大量的冗余信息,通过去除冗余达到压缩的目的,从而解决图像数据量巨大而不便存储与传输的问题｡本文就是从图像压缩的必要性与可能性出发,先介绍了图像压缩方法的分类,接着对几种在静态图像压缩JPEG中所涉及的几种图像压缩方法进行了介绍｡然后具体的论述了JPEG的编码过程,并在此基础上提出了一种改进的离散余弦变换(DCT)即利用查表法来实现DCT变换最后介绍了JPEG标准的色彩系统和它的文件格式,同时对实验结果进行记录和分析,并对静止图像压缩的新技术前景进行了展望｡

本文的静止图像压缩JPEG最终用VB语言实现｡                                                                 

关键词：图像压缩,JPEG,离散余弦变换                             

Abstract

 Modern society has entered a high-speed information time. The informationization development has driven the computer and the multimedia technical unceasing development,.In order to satisfy the visual communication and the image storage demand,The people expected has a unification the highly effective image compression standard appearance. Static images, often used as a computer graphic form but also dynamic images based its compression technology is a very important work, JPEG standard is in this context came into being, JPEG compression technology is very advanced, it used compressed manner detrimental to remove redundant image data. access to high compression rates will be displayed at the same time very rich vivid images, and JPEG is a very flexible format, with the functional-image quality, allowing a different compression ratio of document compression, support multiple compression levels, the greater the compression ratio, the lower the quality; On the contrary, smaller than compressed, the better the quality.

 Not only the image data compression is necessary, moreover also is possible, because the image data has the massive redundant informations, achieves the compression through the elimination redundancy the goal, thus solution image data quantity huge and inconvenient memory and transmission question. This article is embarks from the image compression necessity and the possibility, introduced first the image compression method classification, several image compression method which involved in static state image compression JPEG has then carried on the introduction to several kinds .Then the concrete elaboration JPEG code process, and proposed one kind of improvement separate cosine transformation in this foundation. Finally introduced the JPEG standard color system and its document format, simultaneously carry on the recording and the analysis to the experimental result，and has carried on the forecast to the stationary picture compression new technical prospect.

The this article stationary picture compresses JPEG finally to use the VB language to realize.

  

Key words:  Image Compression ，Jpeg ，Dct