Medical Image Watermarking Technique for Accurate Tamper Detection in ROI and Exact Recovery of ROI

Abstract

In telemedicine while transferring medical images tampers may be introduced. Before making any diagnostic decisions, the integrity of region of interest (ROI) of the received medical image must be verified to avoid misdiagnosis. In this paper, we propose a novel fragile block based medical image watermarking technique to avoid embedding distortion inside ROI, verify integrity of ROI, detect accurately the tampered blocks inside ROI, and recover the original ROI with zero loss. In this proposed method, the medical image is segmented into three sets of pixels: ROI pixels, region of noninterest (RONI) pixels, and border pixels. Then, authentication data and information of ROI are embedded in border pixels. Recovery data of ROI is embedded into RONI. Results of experiments conducted on a number of medical images reveal that the proposed method produces high quality watermarked medical images, identifies the presence of tampers inside ROI with 100% accuracy, and recovers the original ROI without any loss.

Figure 1

Division of medical image into three regions.

Figure 2

Embedding the recovery data of a ROI block into 2 LSBs of pixels in mapped RONI block.

Figure 3

Original, watermarked, and reconstructed medical images. From top to bottom: CT scan, MRI scan, and ultrasound images.

Figure 4

Watermarked medical images (from left to right: CT scan, MRI scan, and ultrasound) with tampers inside ROI.

Figure 5

Recovered medical images (from left to right: CT scan, MRI scan, and ultrasound).