PVO based Reversible Data Hiding with improved embedding capacity and security

Abstract

Background/Objectives: Pixel Value Ordering (PVO) based embedding is a method for image based Reversible Data Hiding (RDH) to plant secret data in minimum and maximum pixel values of each block of the image. This paper serves as an extension of a recently proposed PVO scheme with higher security and embedding capacity. Methods/Statistical Analysis: In this proposed method the image is first divided into equal sized non-overlapping blocks. The pixels in the individual blocks are ordered according to their values and differences between the maximum and the second largest (or minimum and the second smallest) are computed. Then, histograms of these differences are modified to hide secret information. But original scheme rejects a lot of blocks belonging to textured regions of the image which can be used to embed even more data. Findings: The proposed scheme extends the original PVO method by using these rejected blocks to embed data thus increasing the Embedding Capacity. It is observed that although there is an increase in the overall embedding capacity, the degradation in the visual quality is negligible. It is also found that this increase in the capacity affects the robustness. So a simple randomization technique for the block selection process is also proposed. Applications/Improvements: This method can be applied for all the secret communication applications especially Defence, Telemedicine, etc. This proposed method developed further in terms of robust against various steganalysis tools.