The following three examples are simple and they are not being illustrated by
figures.
[ ISOCONT, iso_struct_raster ]
Display a color image of iso_struct_raster (the image is stored in a
CIA raster data structure).
[ ISOCONT, 'm51_dss.fits' ]
Display a color image of m51_dss.fits (the image is stored on disk as a
fits file).
[ ISOCONT, iso_struct_raster, iso_struct_raster ]
Display a color image of iso_struct_raster with an overlay of its own
contour levels.
A legend can be added to the display window using the /PUTINFO
keyword. It contains the color table and the values of contours
displayed, the file name (for a FITS input) or the
SAD6 name (for a raster data structure
input), as well as the current date.
The size of the display window is approximately 650 x 650 screen
pixels. A scaling factor (determined from the image size) is applied
to the input image so that it fills the display window (see section 3.4).
By default, the nearest neighbor method is used for interpolation. If
the bilinear interpolation is the prefered method, the /NOSAMPLE
keyword should be used. However, one should note that in this case
the contour levels will cross color pixels at their edge instead of
their center. This is due to a strange IDL behavior. The effect is
not as important when color pixels are small.