Security enhancement for TPVD steganographic method

The steganographic method named Tri-way Pixel Value Differencing (TPVD) which is a modified version of original Pixel Value Differencing (PVD) steganography, has significantly improved the embedding capacity of original method by embedding secret bits in all horizontal, vertical and diagonal edges of cover images. However, we have shown in this paper that TPVD is drastically vulnerable to statistical analysis of histogram of pixel differences. The occurrence of unusual steps in the derived histogram of pixel differences demonstrates the existence of hidden message. In order to enhance the security, we applied modifications on TPVD steganography and made it secure against current steganalysis. In the proposed modified algorithm, TPVD's embedding phase is mixed with our previously proposed method named EPVD, and the visual characteristics of cover image are genuinely maintained.