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Employing Unsharp Masking for Contrast Enhancement in Reversible Data Hiding

Recently, reversible data hiding (RDH) with contrast enhancement has received substantial interest in order to address the need of applications that deal with poorly illuminated images. The algorithms that have been proposed for this purpose focus on embedding the data in way that improves the global contrast of the image; basically, through manipulating the image intensity histogram. In this paper, we address the issue of improving the local contrast and the sharpness of the image by adapting and formulating the popular unsharp masking technique in a way that makes it suitable for RDH. The new formulation was employed in one of the RDH algorithms and the experimental results showed its capability in improving the sharpness of the image.