JPEG2000-based Still Image Compression Technology Studies

Computer is widely applied to process image and other multimedia.How to compress image effectively for saving resources becomes a research hot spot at present.With the development of image compressing technology and signal processing technology compressed image data not only can decrease the capacity of data and bandwidths, but also can be transmitted through general channels,such as video TV videophone,etc.How to fully utilize existing resources by meeting the demand that people control and communicate with the picture videos,it is an urgent subject to be solved.In fact,it might not need activity picture transmitting to amalgamate actually in a lot of implementation.Transmitting one static picture right away in order of magnitude of second is enough.Based on this demand,this paper deals with the issue of image compressing and implementation based on digital signal processor.Among international standards designed for still image compression, JPEG2000 is the newest standard.Different from the JPEG standard, JPEG2000 bases on discrete wavelet transform and the newest embedded block coding with optimized truncation algorithm, So it not only provides superior compression performance over JPEG, but also provides a set of new features.Region-of-interest coding is one of the features.The region-of-interest coding technology utilizes different compression rate to different area in an image. It can solve the contradiction between the image quality and the compression rate.JEPG2000 not only greatly enhanced the image compression rate,efficiency of compression encoding/decoding implementation, but more importantly through the provision of several special functions,highly optimized the management and organization of image data,coupled with the openness of the standards,in the foreseeable future,JPEG2000 will completely replace the existing image compression technology.The subject first of all analyze the theory and the nature of wavelet transform which based on the advantage of the wavelet,and carried out in-depth research on the standard of JPEG2000;Secondly,properly simulate color images in JPEG2000 standard to accord to the characteristic of wavelet transform and human visual system, analyze and compare to jpeg 2000 which was compressed and jpeg images'properties again, select the natural image, medical image, passport image,figure image and remote images, and test and simulate to them by the wavelet algorithm; it is show that remote images, passport images and medical images were compressed by common wavelet loss transform, image quality is bad, there would be some distortion, so it is unfit able to loss compression, it is fixable for nature images; Finally using the second generation wavelet algorithm by the choice of a variety of common wavelet bases to simulate warp image, through the experiment we can see that the wavelet base of sym8 have a small error, so when compress images to select a appropriate wavelet base is very important.Through simulation experiments, we can see that JPEG2000 compression performance better than JPEG at low-rate, but under the high bit-rate circumstances, JPEG2000 compression performance does not better than JPEG. Therefore, in the appropriate occasions, we can properly select a standard of image compression.