High-capacity reversible data hiding by Maximum-span pixel Pairing on ordered dithered halftone images

In this paper, we propose a high-capacity reversible data hiding method for ordered dithered halftone images. Ordered dithering is a technique that generates a halftone image by simply comparing the pixels in the original gray level image with a dither matrix. In this paper, the dither matrix is applied to pair pixels in such a way that the occurrence frequency of one kind of pixel pair outnumbers that of the other kinds significantly; therefore, a large quantity of data can be hided into these pixel pairs. The embedding and recovering process are conducted through a pair-wise pixel swapping operation, which converts a pixel pair into a pixel pair with opposite characteristic. Our new scheme gives a better performance than Reversible Data hiding by Maximum-span Pairing (RDMP) in terms of both hiding capacity and stego-image visual quality.