AN ENHANCED DIFFERENCE PAIR MAPPING STEGANOGRAPHY METHOD TO IMPROVE EMBEDDING CAPACITY

V.Poongavanam, L. Mary Shamala

Abstract: Reversible Data Hiding (RDH) aims to embed secret message into a cover image by slightly modifying its pixel values, and unlike data hiding, the embedded message as well as the cover image should be completely recovered from the marked content. Many methods have been implemented in RDH to maintain secure confidential data, such as Difference Expansion (DE), Histogram Modification and Difference Pair Method (DPM). But its embedding capacity is quite low and also its PSNR value is low, then it takes more time to complete the process. In order to overcome these issues, Modified Difference Pair Mapping (MDPM) technique of RDH is proposed for embedding extra information in an image by making small modifications to its pixels. MDPM is the process of dividing an image into blocks. Then divide the blocks into embeddable area and non-embeddable area. Embeddable area is used to embed a secret message, and non-embeddable area is used to record the side information. In embeddable area, Centre pixel of 3x3 blocks is chooses as reference pixel, remaining 8 pixels is referred to as non-reference pixels. Then calculate difference value in nonreference pixels. Finally difference histogram has been generated. In that difference histogram, peak point and zero point is obtained. From this peak point and zero point of difference histogram, secret message is embedding. Location map and side information is used in non-embeddable area to extract a secret message and original image. Theoretical analysis indicates that the proposed technique can provide good trade-off between embedding capacity and stego-image quality.

Keywords: Difference Value calculation, Local complexity, Reversible Data Hiding, Reference and Non-reference pixels, Histogram generation, Histogram Pair, Smooth region and Complex region.

DOI: https://doi.org/10.15623/ijret.2014.0319035