Filtering Scheme for ROI Coding by Dynamic Range Compression and Updating Source Picture Filter

Abstract

The region of interest (ROI) coding, which compresses background region more strongly than foreground region, is valuable technology in restricted communication environments such as limited bandwidth and/or storage capacity. This paper proposes a filtering scheme which reduces bit amount by filtering background region in order to support efficient ROI coding on ordinary devices without equipping ROI coding functionality. In particular, dynamic range compression (DRC) filter and updating source picture (USP) filter are added to a low-pass filter, which has been used for conventional filtering scheme. The DRC filter compresses dynamic range of all pixels by down-scaling. The USP filter measures distance between current and previous picture by block basis, and then overwrites the block of the current picture when the distance is smaller than predetermined threshold. Experimental results show that the proposed filtering scheme reduces bit-rate by half compared to the conventional low-pass filter as PSNR-Y of background region is about 30 dB. Compared to uniform quality coding, the proposed filtering scheme reduces bit-rate by 62 %. These results promise to cut down on cost of communication and storage.