Protection of regions of interest against data loss in a generalized multiple description framework

Abstract

Summary form only given. We present a simple and efficient scheme for protecting a region of interest (ROI) in an image sent across generalized multiple description networks. To increase the probability that the ROI is received with high quality, we extend the unequal loss protection framework of MD-SPIHT by adding more redundancy to the ROI than to other parts of the image. The SPIHT algorithm orders data progressively and sends the globally important information first. By adding more redundancy to the earlier parts of the bit stream than to the later parts, MD-SPIHT protects data that are globally important to the image quality more than less important data. In this work, wavelet coefficients corresponding to the ROI are scaled by a large factor so that locally important information is sent in the earlier parts of the bit stream. As a result, the ROI is coded to a higher bit rate than the rest of the image and MD-SPIHT automatically assigns more redundancy to the localized ROI than to the background. Therefore, the ROI is heavily protected at the expense of lower protection in the background. The ROI has a higher probability of being received intact and its quality will be higher than the quality of the background. We show two cases in which 3 out of 8 descriptions are received for 35% redundancy assignment. Without ROI scaling, redundancy is spread to all parts of the image and the quality of the ROI is low. When the ROI is scaled, redundancy is concentrated in the ROI and the quality of the received ROI is higher.