The geotiff format uses user defined tags to georeference a tiff image so the
tiff image knows where it is. There is a library to read/write geotiff and the
USGS uses geotiff for its digital raster graphics. For a path to geotiff search
the web for USGS DRG (I would normally URL but this machine only has e-mail
access to the net)
Regards
bob sandefur