Reversible Image Watermarking for Health Informatics Systems Using Distortion Compensation in Wavelet Domain.

Reversible image watermarking guaranties restoration of both original cover and watermark logo from the watermarked image. Capacity and distortion of the image under reversible watermarking are two important parameters. In this study, a reversible watermarking is investigated by focusing on increasing the embedding capacity and reducing the distortion in medical images. We use integer wavelet transform for embedding one bit of watermark in a transform coefficient. We devise a novel approach that when a coefficient is modified in one iteration, the produced distortion is compensated in the next iteration. This distortion compensation method would result in low distortion rate. The proposed method is tested on four types of medical images including MRI of the brain, cardiac MRI, MRI of breast and intestinal polyp images. The maximum capacity of 1.5 BPP is obtained by using a one-level wavelet transform. Experimental results demonstrate that the proposed method is superior to the stateof-the-art works in terms of capacity and distortion.