Abstract
Medical image data require strict security, confidentiality and integrity. To achieve these stringent requirements, we propose a hybrid watermarking method which embeds a robust watermark in the region of non-interest (RONI) for achieving security and confidentiality, while integrity control is achieved by inserting a fragile watermark into the region of the interest (ROI). First the information to be modified in ROI is separated and is inserted into RONI, which later is used in recovery of the original ROI. Secondly, to avoid the underflow and overflow, a location map is generated for embedding the watermark block-wise by leaving the suspected blocks. This avoids the preprocessing step of histogram modification. The image visual quality, as well as tamper localization, is evaluated. We use weighted peak signal to noise ratio for measuring image quality of watermarked images. Experimental results show that the proposed method outperforms the existing hybrid watermarking techniques.
Acknowledgements
The authors are very grateful to the Ghulam Ishaq Khan Institute of Engineering Sciences and Technology for providing resources and environment for carrying out this research and AGA Khan Hospital Karachi, Pakistan for providing the medical image database for the experimental work. This research is funded by the Quaid-e-Awam University of Engineering Sciences and Technology, Nawabshah, Pakistan under their Inland Scholarship programmme.