1. A system for performing a virtual colonoscopy comprising: (a) a digital image generating system; (b) a storage device, coupled to said digital image generating system, said storage device for storing digital images; and (c) a digital bowel subtraction processor coupled to receive images of a colon from said storage device, said digital bowel subtraction processor for processing the received digital images of the colon to digitally remove the contents of the colon from the image.