I have scans of CAD streets and such and want to get a raster for georeferencing into ARCMap. What are the easy steps to make a targa, geotiff, etc. of a known size, say 2 miles along one side as a test size scenario or any other raster format that can be imported into a layer for subsequent geo reference? Not wedded to any particular form, size, technique, format; just best practice and practical steps. Thanks for any help.