Multi-directional PVD steganography avoiding PDH and boundary issue

Abstract

Pixel value differencing steganography (PVDS) technique efficiently identifies the edge and smooth regions from an image, therefore, the PVDS technique is more suitable for concealing the secret information in an image. Notwithstanding the advantages, the PVDS techniques give rise to some major issues. Most of the PVDS techniques suffer from boundary issue (BI). Further, the majority of the PVDS techniques are exposed to pixel difference histogram (PDH) analysis. In this paper, two improved PVDS based techniques, such as (1) indicator-based PVDS (IPVDS) and (2) multi-directional overlapped PVDS (MDOPVDS) has been proposed to address the BI as well as PDH issue. The IPVDS technique utilizes the concept of indicator pixel in a 2 × 3 pixel block. On the other hand, the MDOPVDS technique utilizes the pixel overlap strategy in a 3 × 3 pixel block using all three directions, such as (1) horizontal, (2) vertical, and (3) diagonal. Results of the proposed technique are evaluated in terms of the conflicting metrics like peak signal-to-noise ratio (PSNR), capacity, and security. Further, it is observed that the proposed technique maintains a good symmetry between the aforementioned conflicting metrics. Additionally, both the proposed technique successfully avoids the BI.