Reversible Data Hiding in Shared Images Using Overlapped Coefficients in Polynomials

Reversible data hiding (RDH) in shared images is an effective technique for securely storing and managing confidential images. However, most existing methods suffer from a noticeable data expansion and cannot achieve a good trade-off between data expansion and embedding rate. To address this issue, we propose a novel RDH in shared images (RDHSI) using overlapped coefficients in polynomials. In the proposed method, an original image is compressed losslessly to reduce its size before sharing, and then the compressed image is divided into a series of groups, where any two adjacent groups have an overlapped part. Next, each group is shared by our proposed (<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">k</i>, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</i>)-threshold based sharing technique, which is performed by the polynomial over Galois field GF(2<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">8</sup>) with overlapped coefficients. Finally, data embedding is performed on each shared image by bit replacement according to a constructed 0-1 matrix. Experimental results demonstrate that the proposed method can effectively reduce the sizes of the shared images and achieve a high embedding capacity.