Distortion-Free Robust Reversible Watermarking by Modifying and Recording IWT Means of Image Blocks

This paper presents a novel distortion-free robust reversible watermarking scheme by modifying and recording the mean information of the integer wavelet transform (IWT) middle-frequency of the image blocks sized \(8\times 8\). The proposed method utilizes multiple watermarking by embedding the watermark with the robust watermarking method at first and a following reversible watermarking method to embed the mean information used to recover the cover image. The cover image is first divided into non-overlapping blocks sized \(8\times 8\) and applied 5/3 IWT to transform the blocks. One watermark bit is embedding into the HL and LH sub-bands of a block by modifying their mean values. The mean values are calculated by randomly choosing 10 coefficients instead of all the 16 coefficients so that the mean value has one decimal place at most and can be reversibly embedded for the recovery of the original cover image. Experimental results have shown the proposed method is blind, and provides better performance in the invisibility and the robustness against JPEG/JPEG2000 and noise attacks.