Directional PVO for reversible data hiding scheme with image interpolation

Pixel Value Ordering (PVO) is an efficient data hiding scheme where pixels are ranked in ascending order within an image block and then modify minimum and maximum pixel value to embed secret data. The embedding capacity of existing PVO based data hiding schemes were limited to embed only two bits in a row of any block and unable to perform repeated embedding. To solve the existing problem, we have proposed a generalized directional PVO (DPVO) with varying block size. The original image is partitioned into blocks and then enlarged using image interpolation. A new parameter (α) is introduced and added with maximum pixel value and subtracted from minimum pixel value to maintain the order of the rank which is dependent on the size of the image block. To improve data hiding capacity, overlapped embedding has been considered in three different directions (1) Horizontal, (2) Vertical and (3) Diagonal of each block. Experiments show that the proposed scheme has a good margin of performance compared with the state-of-the-art methods. Several steganographic analysis deemed robust against several attacks.