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

Region-of-Interest (ROI) 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 a novel 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 two-fold advantages, namely (1) better flexibility and low loss in image quality due to QIM and (2) better decoding reliability that leads to better access control. Only the authorized users having the full knowledge of the secret key restore the full quality of ROI. Simulation results duly support this claims

Capacity-Security Analysis Of Data Hiding Technologies

In this paper we consider the problem of joint capacitysecurity analysis of data hiding technologies from the communications point of view. First, we formulate data hiding as an optimal encoding problem for different operational regimes, that include both robust digital watermarking and steganography. This provides the corresponding estimation of the hidden data statistics, as well as of the rates approaching embedding capacity. Secondly, we formulate the problem of blind stochastic hidden data detection based on the developed watermark statistics. Finally, we estimate the error of watermark detection and the variance of the watermark estimation that determine the system security