Image Progressive Transmission And Region Of Interest Coding Based On JPEG2000

In recent years, with the rapid popularity of multimedia and network, the image data becomes one kind of more and more important data format which is transmitted in the network. The image Data has three notable features. First, the data quantity is huge; second, the data redundancy is great; and the third is that the image can still be correctly identified when its quality is not very high. The first feature shows image data has the compression necessity; and the other two features show that image data has the compression possibility.The DWT is used by the JPEG2000 which is the new generation of image compression standard. DWT is not only effective to the steady signals, but also effective to the non-steady signals. After the DWT, most energy is concentrated to a small number of wavelet coefficients, which provides a convenience for the image compression.On the network, because of bandwidth limitations, the data received by receiving terminations may not be complete. In order to restore a lower quality image which is integrity by partial data, the progressive transmission is introduced. Through transmitting the approximate outline of the image first, then transmitting the detail information, the process of receiving image becomes a process of gradual improving the quality of the image. When people observe and understand images, they always consciously or unconsciously centralize attention on some specific regions, and expect these regions have a high visual quality. Therefore, in the image transmission process, the regions which people are interested in are transmitted first, which can minimize data loss of these regions. How to determine the shape of ROI when coding the region of interest is a key issue. The gray mask covered by block can solve the question of marking a number of ROI with arbitrary shape at the same time.The receiver of the image can receive a general picture of the entire image as soon as possible in the smaller bandwidth circumstances when adopt the strategy of progressive transmission and ROI coding. Even through the data link sudden stops, the information already obtained must be the largest and most important information.