1. An image processing system for displaying an image of a body volume, the system comprising means ( 12 ) for receiving three dimensional image data in respect of said body volume, silhouette rendering means ( 24 ) for generating a direct volume silhouette rendering of said three dimensional image data, said silhouette rendering being comprised of values proportional to the translucency of voxels of said three dimensional image data, and means ( 40 ) for displaying the resultant silhouette rendering.