Medical Image Watermarking Based on DWT and ICA for Copyright Protection

Abstract

Digital watermarking has been proposed to increase medical image security, confidentiality and integrity. Medical image watermarking is a special subcategory of image watermarking in the sense that the images have special requirements. Particularly, watermarked medical images should not differ perceptually from their original counterparts, because the clinical reading of the images for diagnosis must not be affected. Hence, in this paper, a robust and imperceptible watermarking technique based on discrete wavelet transform (DWT) is proposed for medical images. For extraction, a blind source separation technique, namely, independent component analysis is attempted. Conventional extraction techniques need embedding parameters such as strength, location and information about watermark or original image, whereas, ICA extracts the watermark without the use of these parameters. The quality of watermarked image and extracted watermark are measured in terms of peak signal to noise ratio (PSNR) and normalized correlation (NC) values respectively. Robustness of the proposed scheme is validated against various image processing attacks. The proposed work is attempted on color images also. A true color image is split into red, green and blue components, where watermark is embedded in each plane individually followed by extraction. Performance of the proposed scheme is compared among the color components, and it is recommended that blue plane is the better choice of embedding watermark for medical color images.