Reversible Data Hiding Scheme Based on Difference Expansion Using Shiftable Block Strategy for Enhancing Image Fidelity

The difference expansion (DE) proposed by the Tian is one of the most famous methods of reversible information hiding. This method uses the difference between pixels to embed secret information into the image and can restore the stego-image to the original image, to reach a high embedding capacity and keep low distortion. However, in applications using multi-layer embedding, difference expansion may cause the image quality to deteriorate drastically. In this paper, we proposed a multi-layer shiftable block strategy to modify the block partitioning to hide the secret message. This is done to prevent the data from being hidden in the same block of consecutive layers. Therefore, image distortion is not amplified by the pixel difference of the previous layer, causing a recursive effect by hiding the secret message in the latter layer; thus enhancing image fidelity. The experimental results show an improvement in the image quality of the proposed method.