ROI Based Quality Access Control of Compressed Color Image using DWT via Lifting

Abstract

ROI (Region of Interest) in an image or video signal contains important information and may be used for access control at various qualities using multiresolution analysis (MRA). This paper proposes quality access control method of compressed color image by modulating the coefficients of ROI at various levels. Data modulation causes visual degradation in the original image and plays the key role in access control through reversible process. The modulation information, in the form of a secret key, is embedded in non-ROI part of the chrominance blue (Cb) channel of the color image using quantization index modulation (QIM). Lifting based DWT, rather than conventional DWT, is used to decompose the original image in order to achieve twofold advantages of (1) low loss in image quality due to QIM and (2) better decoding reliability. Only the authorized user having the full knowledge of the secret key restores the full quality of ROI. Simulation results duly support this claims.