The Study On The ROI-Based Image Coding And Transmission

Recently, ROI-based image coding and transmission have become one hot topic in digital image processing. ROI, the abbreviation of Region of Interest, represent the area that will be interested by human's eyes in one image. ROI-based image coding utilizes different compression to ROI and non-ROI area in an image;it can solve the contradiction between the image quality and the compression rate. ROI-based image transmission not only transmits ROI firstly, but also gives more error resilience to the ROI.In this paper, firstly, the research background and development of image coding especially the ROI-based image coding are introduced, in this part the classic ROI extraction and coding methods are emphasized. Then the basic principle and architecture of wavelet-based image coding are brought forward, in this part the choice of wavelet transformation, the organization of wavelet coefficient and the choice of wavelet base are introduced respectively. Thirdly, a novel ROI-based image coding algorithm is proposed. By using different wavelet bases and bit rate to transform and code the original ROI and non-ROI separately, combined with the Set Partitioning in Hierarchical Trees (SPIHT), the compression quality between ROI and non-ROI can be controlled flexibly. Lastly, a wavelet based ROI progressive image transmission algorithm is proposed. This algorithm utilizes the superiority of wavelet and organizes one sound code stream which is consistent with the human visual system (HVS) .By combining the ROI with the progressive image transmission, this algorithm enhances the efficiency of the image transmission.