Rate-controlled, region-of-interest-based image coding with JPEG-LS

Abstract

Since the standardization of JPEG-LS, several improvements and variations to the original algorithms have been proposed. In this paper we propose a Region of Interest (ROT) based coding strategy for JPEG-LS that has the additional ability of providing effective rate controlled image compression. Given a single ROT or multiple ROTs of a fixed or arbitrary shape, the scheme we propose is able to compress a given image by a required ratio, whilst maintaining the subjective image of the ROTs at either lossless or at a quality specified by a Target Compression Ratio ( TCR) of the ROT. We provide experimental results to compare the performance of the proposed rate-control algorithm with the state of the art near lossless rate control schemes. We show that the proposed scheme is able to achieve much higher TCRs, at increased accuracy and better objective image quality, using a less computationally intensive rate control algorithm. Finally we demonstrate that the proposed ROT based coding scheme can be used to extend the applicability of JPEG-LS to medical and satellite imaging applications and provides a useful alternative to JPEG-2000 based ROT coding.