Wavelet Transform-based Still Image Compression Technology And Its Applications

With the rapid growth of mobile communication and Internet, voice and data communication cannot satisfy people's need anymore. More and more experts begin to be interested in multimedia communication. In the view of communication system, image compression belongs to source coding technology. It plays an important part in the realization of a multimedia communication system.As everybody knows, JPEG has been a great success. Nowadays, most of the pictures are transmitted over Internet in JPEG format. But JPEG has its weak points too. For example, its performance is poor in a low bitrate condition. One reason for its bad performance is that it is based on DCT. Although DCT provides excellent performance in energy concentration and decorrelation, it cannot provide controllable localization in both time and frequency domains. As a better transform, wavelet transform attracts more and more experts. But wavelet transform doesn't have an unique base function. Which wavelet base to be used, and how to organize wavelet coefficients efficiently are very important to a wavelet-based system.JPEG 2000 is a next-generation still image compression standard based on wavelet. It provides higher compression ratio, better reconstruct image, and broader application areas. So we focus on the algorithms used in JPEG 2000.This thesis gives an overview of JPEG 2000 and analyses a practical JPEG 2000 file. Some discussions are given on how to choose a better wavelet base and a proper quantization method. The most important result of the research is a software implemented these important algorithms. This software was developed on Visual C++ platform. Some cdmparisons between this software and JPEG are given, and we can see that wavelet-based method does overcome the shortcomings of JPEG.