Novel design techniques for enhancing capacity and security of reversible data hiding in digital images

Abstract

Recently, more importance is given to Reversible Data Hiding newline(RDH) scheme because it restores original cover image without loss after the newlinesecret data is extracted. RDH techniques are useful in secret communication, newlineauthentication and integrity checking. Capacity and security are the important newlineperformance measures in data hiding schemes because when the hiding newlinecapacity is high, large amount of secret data can be embedded in the cover newlineimage in a secure manner. But the problem is when the capacity increases newlineimage quality decreases. In this thesis, two novel design techniques for RDH newlineare proposed: one is Invisible and the other is Visible. newlineThe proposed invisible RDH design technique is a block based newlinetechnique that has high capacity with low distortion. The cover image is newlinedivided into blocks and all the pixels in the block are converted into odd value newlineor even value by computing the optimal value of the block. The optimal value newlineis a value which one is very nearer to all the pixels in the block. Five newlineparameters: mean, median, range, harmonic mean and max histogram are newlineused to compute optimal value in a block. Secret data is directly embedded newlineinto the blocks using odd even property. In the receiving end, after extracting newlinesecret data from the stego-image, the cover image can be recovered to its newlineoriginal form by computing the same optimal value. A data hiding key is used newlineto enhance security of the data hiding system. No location map is used to newlineidentify the overflow/underflow pixels, instead the recomputation of optimal newlinevalue in the receiving end itself can be used to identify the newlineoverflow/underflow pixels newline newline