Little has been said so far about the image data format that PHOTOM programs will work with. The
native format that these use is the Starlink NDF (see SUN/33). Files that contain an NDF are
identified by the extension ‘.sdf’
and are accessed by PHOTOM programs when you just
give the filename without an extension. So for instance if you have a file ‘image.sdf’
that
contains an NDF then you just supply the response ‘image’
when prompted for an input
image.
In addition to the NDF PHOTOM programs can also be made to use images in other formats, such
as disk FITS, old-style FIGARO and IRAF, using the ‘on-the-fly’ conversion abilities of
the NDF library. To make this work for you, you need to setup the CONVERT (SUN/55)
package and then pass images to PHOTOM programs together with their file extensions. So
if you wanted to work on the IRAF image ‘pix.imh’
you’d use a command sequence
like:
In this case the file extension “tells” PHOTOM and the KAPPA program DISPLAY that they have an IRAF image. You should look at the CONVERT document (SUN/55) to see the list of formats that can be processed.