New Region of Interest Image Coding Based on Multiple Bitplanes Up-Down Shift Using Improved SPECK Algorithm

Image compression based on region of interest (ROI) means to code the important regions in an image with high quality and to code other regions (Background-BG) with relatively low quality. Based on this idea, a flexible ROI image coding method called multiple bitplanes up-down shift (MBUShift) is presented. First, the new method divides all original bitplanes into three parts according to different importance of ROI and BG bitplanes. Second, the most significant ROI and BG bitplanes are shifted up, the least significant ROI and BG bitplanes are shifted down, and another bitplanes are not shifted. Third, the improved SPECK algorithm based on quadtree partitioning is applied for encoder and decoder. The unique characteristics of the new method lie in the combination of good ROI compression performance and low algorithm complexity. Experimental results indicate that the proposed method significantly outperforms the previous ROI coding schemes in overall ROI coding performance