A set of algorithms has been developed at USGS Flagstaff for displaying digital map data in raster format. The set includes: FILLIN, which assigns a specified attribute code to units of a map which have been outlined on a digitizer and converted to raster format; FILBND, which removes the outlines; ZIP, which adds patterns to the map units; and COLOR, which provides a simplified process for creating color separation plates for either photographic or lithographic reproduction. - Authors