Half Difference Expansion Based Reversible Data Hiding Scheme for Medical Image Forensics

Medical image authentication is an important area which attempts to establish ownership authentication and data authentication of medical images.

In this paper, we propose a new reversible watermarking scheme based on a novel half difference expansion technique for medical image forensics.

Conventional difference expansion based reversible watermarking scheme generates watermarked images with less visual quality, and the embedding rate was considerably less due to the high probability of overflow or underflow. In the proposed scheme, the quality of the watermarked image has been improved by modifying the traditional difference expansion based watermarking scheme, half of the difference between two pixels will be expanded during watermarking. The modification of pixels during watermarking is limited by expanding half of the pixel difference, which helps to obtain watermarked images with better visual quality and improved embedding rate due to less chance of overflow or underflow during watermarking. We also propose a tamper detection localization process to detect the tampered regions from the watermarked image.

Experimental study of the proposed scheme on the standard medical images from Osrix medical image data set shows that the proposed watermarking scheme outperforms the existing schemes in terms of visual quality of the watermarked image and embedding rate.

The overhead related to location map and parity information need to be addressed in future works to improve the proposed scheme.