High-fidelity reversible data hiding based on PVO and median preserving

This paper aims to provide a comprehensive methodology for transmitting data securely between smart city applications. Reversible data hiding technique is widely used to protect secret information. Pixel value ordering (PVO) is an effective method of reversible data hiding (RDH) that sorts the pixels of a block based on their values. The pixel-based PVO (PPVO) method changes the predictive manner in PVO and achieves a high embedding capacity. However, in PPVO, the errors between the predicted pixel and the current pixel close to zero are not utilized. We propose a novel high-capacity reversible data hiding method based on PVO and median preservation to promote hiding capacity. The median preserving strategy in each block is used to compute the predicted error and to determine the smoothness of the area. If the block is a smooth area, more predicted errors are generated and fall within the range of [− 1, 1]. A modified multiple histogram scheme is applied to hide messages using predicted error shifting. Experimental results show that the proposed method has superior hiding capacity performances than that of the previous PVO-based methods.