Image Composition via Lookup Table Manipulation

The Image Composition Language provides a convenient way for programmers of interactive graphics application programs to define how the video lookup table of a raster display system is to be loaded. ICL allows one or several images stored in the frame buffer to be combined or modified in a variety of ways. ICL treats these images as variables, and provides arithmetic, relational, and conditional operators to combine the images, scalar variables, and constants in such image composition expressions as old_image*t+new_image*(1.0-t) and ifimager>0.5thenimage ?? {0.5,0,0,} else image endif. Use of the Image Composition Language relieves programmers of the tedium usually associated with loading the video lookup table to do simple image composition and modification.