Research On Image Data Compression At The Age Of The Network

Data compression technology is an effective method to deal with the problem of information blast, and the higher quality and the lower bit rate are the aim of multimedia data compression. With the increasing use of multimedia technologies and networks technologies, people have put forward the higher requirement at quality performance and some new applications. Because of the necessity and possibility of multimedia data compression, research on multimedia data compression is a popular and active field; especially the image data compression has a very important status in it. So ISO developed a new still image compression standard: JPEG2000, which is the late achievement in image compression technology.In this paper, we summarize and compare the previous method of image data compression, analyze and give a method of JPEG image encoder-decoder based on DCT. And primary through analyzing the main algorithm (EBCOT) in the JPEG2000, this paper describes the new features and the advantages of the JPEG2000 over the previous standard. The main difference from the JPEG standard is the use of DWT rather than DCT. Based on EBCOT algorithm, the paper gives a simple wavelet-based image-coding scheme. The author makes it in one demo system of JPEG2000 encode-decoder by programming with VC++ and Delphi, including improve low bit-rats compression performance, lossless and lossy compression.During the experiment, we compare the results of image data compression by JPEG and our JPEG2000 method respectively, also by LuraWave SmartCompress v3.0 Software and our JPEG2000 method respectively. As a conclusion, the JPEG stationary picture has a good compressing effect on middle and high bit rate, but exists a serious diamond effect at low bit rate resulting from the block-based DCT scheme. So JPEG images can not very well make the needs transmitting images by networks at high compressing rate. While JPEG2000 image performs very well at all bit rates. The experiment shows that the compression images have better vision effect by our JPEG2000 method, and it has some characters compared with other JPEG2000 compression software.