OM2 and GIMP obviously don't get along, so I have settled on UFRaw and Gimp.
You can then open your ORFs in GIMP and UFRaw starts automatically.
Setting the Print size correctly, after maybe adding a border by increasing the
canvas size by, say, 20 pixels, and flattening with an appropriate background
colour, gives a good print result. OM2 is in danger of being nudged off my
Gimp-user mailing list