According to the G.Projector manual at http://www.giss.nasa.gov/tools/gprojector/help/ : "If you use larger input images — maps 5000×2500 pixels or larger — from other sources, please be aware that G.Projector may encounter memory problems if you have more than one map window open at a time. The program may hang or report a "heap space" error if the source image is in excess of 10,000×5000 pixels."