Medical Image Watermarking: A Study On Image Degradation

Digital watermarking has been proposed to increase medical image security, confidentiality and integrity. Med-ical image watermarking is a special subcategory of im-age watermarking in the sense that the images have special requirements. Particularly, watermarked medical images should not differ perceptually from their original counter-parts, because the clinical reading of the images (e.g. for diagnosis) must not be affected. This paper presents a pre-liminary study on the degradation of medical images when embedded with different watermarks, using a variety of pop-ular systems. Image quality is measured with a number of widely used metrics, which have been applied elsewhere in image processing. The general conclusion that arises from the results is that typical watermark embedding can cause numerical and perceptual errors in an image. The greater the robustness of a watermark, the greater the errors are likely to be. Consequently medical image watermarking re-mains an open area for research, and it appears that a se-lection of different watermarks for different medical image types is the most appropriate solution to the generic prob-lem.