Research On Image Compression Based On JPEG Algorithm And VQ Algorithm

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.