1.4.1 07074, a Graphics Hill, Volume distributed [3]. this 2 ~ddress: 3 copyright July commercial a provided f is that 2C46S is are 1.3.4 Laboratories, permission the Machinery. the To advantage, 'f direct republish, made requires granted a all permission. material © Permission 1.3.3 Room a a the current a Bell be Murray a appear, publication Compositing Digital Images Thomas Porter Tom Duff Computer Graphics Project Lucasfilm Ltd. 1. Introduction ABSTRACT Increasingly, we find that complex three dimensional Most computer graphics pictures have been computed all scene cannot be fully rendered by single program. The at once, so that the rendering program takes care of wealth of literature on rendering polygons and curved computations relating to the overlap of objects. There surfaces, handling the special cases of fractals and spheres several applications, however, where elements must and quadrics and triangles, implementing refinements for rendered separately, relying on eompositing techniques for texture mapping and bump mapping, noting speed-ups on the anti-aliased accumulation of the full image. This paper the basis of coherence or depth complexity in the scene, presents the case for four-channel pictures, demonstrating suggests that multiple programs are necessary. that matte component can computed similarly to the color channels. The paper discusses guidelines for In fact, reliance on single ...