Data hiding based quality access control of digital images using adaptive QIM and lifting

摘要

This paper proposes a joint data-hiding and data modulation scheme to serve the purpose of quality access control of image(s) using quantization index modulation (QIM). The combined effect of external information embedding and data modulation cause visual degradation and may be used in access control through reversible process. The degree of deterioration depends on the amount of external data insertion, amount of data modulation as well as step size used in QIM. A weight function (q) and the quantization step size (Δb) of JPEG 2000 are used for defining the step size of QIM. Lifting based discrete wavelet transform (DWT), instead of conventional DWT, is used to decompose the original image in order to achieve advantages, namely low loss in image quality due to QIM, better watermark decoding reliability and high embedding capacity for a given embedding distortion. At the decoder, data are demodulated first and watermark bits are then extracted using minimum distance decoding. Extracted watermark is used to suppress self-noise (SN) that provides better quality of image. Simulation results have shown that an improvement in peak-signal-to-noise-ratio (PSNR), mean structural-similarity-index-measure (MSSIM) and Watson distance by an amount of about 30%, 12% and 77%, respectively, are gained by authorized user when 50% coefficients of high–high (HH) coefficients are modulated.