Figure 12:
[ ISOCONT, iso_struct_raster, 'm51_dss.fits', MAGNIFY=4. ]
Display a color image of iso_struct_raster, with contour levels of
m51_dss.fits (high resolution image). If the MAGNIFY keyword is not used,
then the resolution of the high resolution image is decreased
in order to match that of the first image. Using the MAGNIFY=4 option
the color image is rebined with an expansion factor of 4
(using nearest neighbor values) in order to virtually improve its
resolution and make the superimposed contours look smoother.
Another possibility is to select the second image as the astrometric
reference, using the REF keyword (see Fig 11).