Improved reversible data hiding using pixel-based pixel value grouping

Pixel value grouping (PVG) has been proved effective in exploiting block redundancy. However, the uniform pixel block still exposes the deficiency in generating prediction errors in a block-by-block manner. In this paper, a novel pixel-based pixel value grouping (PPVG) is proposed with which the embedding primitive switches from pixel block to pixel and PVG is fulfilled on context pixels to calculate predicted value. In this way, not only the advantage of PVG can be preserved but also all pixels can be fully utilized and classified. Then more and smaller expandable prediction errors can be obtained by utilizing pixels in smooth regions with priority. As a result, the embedding procedure can embed more data with less distortion. Experimental results verify that the proposed scheme outperforms other state-of-the-art schemes.