RFITS reads a standard format FITS file by typing:
IDL> img = rfits(infil, header=header)
where img is the image, infil is the input file name, and is the string array with the data header in it. It is possible to use the option to convert the data into some physical units. For example, the magnetogram data would be converted to gauss.
IDL> img = rfits('/yd0/gbo92_37/gkm920907.1442', head=head, /scale)