prob with memory device

hi, after several attempts, i still haven't managed to create a memory-only context, draw a graphic on it and finally save it to disk (as a bmp, jpg or tif). the "least" problem i encountered were wrong colors in the resulting files. could someone please email me an example program (or fragment) for this purpose? or perhaps just the necessary initialisation commands (GrSetMode, GrCreate*Context, ...)? thank you very much, christian