Reversible data hiding for ordered dithered halftone images

A reversible data hiding method is a data hiding technique that hides data into cover media such that the cover media can be recovered distortion-free after the hidden data are retrieved. In this paper, we present a very robust reversible watermarking algorithm for all kinds of ordered dithered halftone images. The proposed method utilizes a new decomposition method to divide the pixels into two groups with very large statistical difference between each other so that the watermark can be decoded without error even under severely degradation. The experimental results show that the halftone image can be completely recovered if the watermarked image is intact and the correct decoding rate is 100% for the print/scan attack and degradation less than 25%.