New approach to multiple regions of interest image coding using IWT and bitplane-classification shift

Regions of interest (ROI) image coding allows ROIs of the image which are of higher importance than the background (BG). In this paper, a new approach for multiple ROI coding, called bitplane classification shift (BC-shift), is presented. In this method, all the bitplanes of the image coefficients are composed of three parts - most significant ROI bitplanes, general significant ROIs and BG bitplanes, and least significant BG bitplanes. For a single ROI, the new method can encode an ROI with any quality by up-shifting the most significant ROI bitplanes and downshifting the least significant BG bitplanes. When multiple regions of interest are encoded, it can encode and transmit a certain number bitplanes of ROIs according to different degrees of interest. The experiments show that the new method, in addition to having a small complexity and bitrate overhead, can handle multiple ROIs of arbitrary shapes, without coding shape information, flexibly.