LANDSCAPE If this keyword is set, the output is in Landscape
mode. Otherwise, Portrait mode is used.
PAGESIZE: Set this keyword to a string indicating the type
of PostScript page size you want. Current values are "LETTER",
"LEGAL", and "A4". Default is "LETTER".
RGB_ERROR: Some printers (particularly attached to LINUX machines) cannot
load a 24-bit image. You get this error message:
%Can't set RGB color on an indexed destination.
If this happens to you, set this keyword and the 24-bit image will
be made into a 2D image with color table vectors. Colors are not
quaranteed to be accurate with this method, but in practice it is
not usually too bad.
IDL> PrintWindow, /RGB_Error