JPEG 2000 and Region of Interest Coding

This paper details work undertaken on the application of JPEG 2000, the recent ISO/ITU-T image compression standard based on wavelet technology, to region of interest (ROI) coding. The paper briefly outlines the JPEG 2000 encoding algorithm and explains how the packet structure of the JPEG 2000 bit-stream enables an encoded image to be decoded in a variety of ways dependent upon the application. The three methods by which ROI coding can be achieved in JPEG 2000 (tiling; coefficient scaling; and code-block selection) are then outlined and their relative performance empirically investigated. The experimental results show that there are a number of parameters that control the effectiveness of ROI coding, the most important being the size and number of regions of interest, code-block size, and target bit rate. Finally, some initial results are presented on the application of ROI coding to face images.