MAP_POLAR /BACKGROUND

        [ADVANCED\]MAP_POLAR GenericBegin  [GenericEnd]  /BACKGROUND  Type  [Min
    Max] [/STEP Step Xfirst Yfirst]

    Show  the polarization vectors derived from the Polarization Angle and Frac-
    tion maps overlaid on a background image.

    Type can be I for total intensity, F for fractional polarization in percent,
    or P for the polarized intensity. Min and Max indicate the SCALE to be  used
    for  the  color scaling (through a temporary assignments of the SCALE values
    for SHOW command called by MAP_POLAR).

    Type, Min, and Max, like Step, Xfirst, Yfirst are "sticky" (remanent):  they
    keep  the previous value until a new one is specified, or are reset to their
    default values by use of the /COMPUTE option.  Default is I for Type, 0  for
    Min and Max, which implies an automatic scaling to the data range.