Research On Region Of Interest Coding Algorithm

With the development of technology, compute has developed to processing the multimedia information of audio, image and video from the earlier pure digital calculate. Not only these contents of the multimedia information are miscellaneous, but the information need to be processed is becoming larger and larger. So the image data processing is the key technology of the multimedia application. In actual image information processing, because of different subjective goal, people can also give different regard to the different region of the image. Some specific area of the still image may become the key observation, but the background which is outside this area cannot have the too much information needed. When compression, these specific regions can obtain the better compression effect than that of the background, and which can be first processed in the transmission process. This is so-called "Region of Interest (ROI)" compression processing in the image process.In this thesis, the region of interest coding algorithm is studied, and two modified ROI coding methods are presented according to the actual application, which can improve the agility and efficiency of the image coding. The structure of this thesis is as follows: In the second chapter, we elaborate the basic concept and feasibility of digital image compression, and then introduce the method of efficiency appraisal and quality appraisal in image compression. In the third chapter, we elaborate the embedded loss and lossless coding thought more comprehensively. Based on this, we discusse three embedded coding algorithm, such as EZW, SPIHT and SPECK. In the fourth chapter, we introduce the JPEG2000 standard and some principles. In the fifth chapter, we analyze two kinds of region of interest (ROI) coding methods- the general scaling based method and the maximum shift (Maxshift) method. Then we give the relation between PSNR and bit rate of the coding image, comparing the image quality of ROI coding with that of JPEG coding. We develop a software of image ROI coding and display by MFC using object-oriented programming thought. We propose two modified ROI coding methods which can fix the shortcoming of the above two method. This thesis has three innovations:1. Giving the general step of the region of interest image coding and develop the still image encoding software based on ROI using MFC.2. Through the compare of the compressed quality using different compressed methods, giving a method to analyze the effect of compression by using the relation between SNR and bit rate of the coding image.3. Giving two modified ROI coding methods which can not only assure the priority of ROI, but make the utmost to reserve the important information of the background. And they can both improve the agility and the efficiency of the image coding.