A conceptual model of raster graphics systems

In this paper we present a conceptual model of raster graphics systems which integrates, at a suitable level of abstraction, the major features found in both contemporary and anticipated graphics systems. These features are the refresh buffer; the image creation (scan-conversion) system; the single address-space architecture which integrates the address space of the refresh buffer with those of the image creation system and the associated general-purpose computer; the RasterOp or BitBlt instructions found in some single address-space architectures; the video look-up table, and refresh buffer to screen transformations. Also included are the major components from the conceptual model of vector graphics systems which are embodied in the ACM/SIGGGRAPH/GSPC Core System. Using the conceptual model as a base, we proceed to sketch out the capabilities we have defined in a substantial addition to the Core System. The capabilities are currently being implemented as part of the George Washington University Core System.