【作者】 纪心毅；

【导师】 李国丽；

【作者基本信息】 合肥工业大学 ， 检测技术与自动化装置， 2008， 硕士

【摘要】 图像的数字化表示使得图像信号可以高质量地传输,也便于图像的检索、分析、处理和存储。但是数字图像的表示需要大量的数据,必须进行图像的压缩。图像压缩的目的是消除图像中的大量冗余信息,提高图像传输的效率,减少图像的存储容量。随着医学的不断进步和发展,产生了大量的图像数据,给医学图像的存储和传输技术提出了严峻的挑战,因此数字图像压缩技术在医学图像中的应用也日益广泛。正是由于其广泛的应用,图像压缩技术的研究就变得相当有意义。JPEG(Joint Photographic Experts Group)联合摄影专家组,制定出了第一套国标静态图像压缩标准JPEG,JPEG压缩算法由于其较高的压缩比和理想的压缩效果,是目前应用最广泛的图像压缩方法之一。矢量量化(VQ)是,在量化的时候,用码书中与输入矢量最匹配的码字来代替这个输入矢量的量化方法。矢量量化作为一种有效的有损压缩技术,其突出优点是压缩比大以及解码算法简单,因此它已经成为数据压缩编码的重要技术之一。本文在介绍JPEG图像压缩算法、矢量量化图像压缩技术的基础上,用JPEG和VQ这两种算法分别对lena图像和医学中的CT图像进行了压缩处理,得到在不同压缩比下的峰值信噪比,并对压缩结果进行了分析比较。实验结果表明,当压缩比较低的时候,JPEG压缩算法的压缩质量较高,而随着压缩比不断加大,矢量量化编码算法的压缩效果较JPEG压缩算法更具优越性。更多还原

【Abstract】 Digital image technology brings high-quality image signal transmission, facilitates image index, image analysis, image processing and storage .But because the expression of image requires massive data, image compression is needed. The purpose of image compression is to eliminate numerous information redundance, increase the efficiency of image transmission, and deduce image storage capacity.With the development of medicine, numerous image data are produced every day.This brings severe challenge to medical image storage and transmission, so digital image compression technology is widely used in medical image field also.Therefore, study on image compression technology is considerably significant because of its wide application.JPEG (Joint Photographic Experts Group) institution drew up the first standard static image compression criterion-JPEG. Due to high compression ratio and excellent compression results, JPEG algorithm is one of the widelist used image compression techniques currently. VQ (Vector Quantization) replaces the input vectors with codevectors which are matched with input vectors from the codebook.As an effective lossy data compression algorithm, VQ’s excellent feature is high compression ratio and simple decode algorithm. VQ has become a significant data compression code technology.Based on the summary of JPEG and VQ, "lena" and CT (Computed Tomography) image were processed using JPEG and VQ in this article, PSNR (Peak Signal to Noise Ratio) values at different compression ratios were obtained. Comparing and analysis of the compression results showed that JPEG has higher compression quality at lower compression ratio, and VQ’s compression quality is higher when compression ratio is higher.更多还原