5 Image Display

 5.1 KAPPA
 5.2 SAOimage
 5.3 GAIA


The KAPPA display program displays a 1- or 2-dimensional NDF in (by default) a GWM X Windows window. This GWM window can then be accessed by other Starlink applications (including other KAPPA applications) and the image manipulated. For instance, before carrying out photometry using the PHOTOM package you would display your CCD image using the KAPPA display command.

More information about KAPPA, and the display application, can be found in SUN/95.

5.2 SAOimage

SAOimage is a utility for displaying astronomical images in the X Window environment. It was written at the Smithsonian Astrophysical Observatory by Mike Van Hilst in 1990 and is now maintained by Doug Mink. Image files (including NDF) can be read directly, or image data may be passed through a named pipe from IRAF display tasks.

SAOimage provides a large selection of options for zooming, panning, scaling, coloring, pixel readback, display blinking, and region specification.

The SAOimage desktop includes, a main image display window, a button menu panel, a display magnifier, a pan and zoom reference image, and a color bar. A color table graph window can be brought up by clicking on the color bar at the bottom of the SAOimage desktop.

A quick introduction to SAOimage can be found in SUN/166. Further information can then be found in the SAOimage User Manual (MUD/140) which is distributed in LaTeX form with the SAOimage source code in the ‘doc’ subdirectory. Further information is also available on the web on the SAOimage Home Page at http://tdc-www.harvard.edu/software/saoimage.html.

5.2.1 Printing in SAOimage

One of the most commonly asked questions when dealing with image display in SAOimage is how to change the default printer. Under csh or tcsh (the default shell at Starlink sites) the following lines should be put in your .cshrc file:

  setenv PRINTER printer
  setenv PSPRINTER printer
  setenv R_DISPOSE ’lpr -Pprinter -r %s’

where printer is the name of the printer you want to make your default printer.

5.3 GAIA

GAIA is an image display tool written in C++ by Peter Draper based on the SkyCat image display and catalogue browsing tool developed as part of the VLT project at ESO. GAIA is extendable and can integrate other applications. Currently extensions are provided that allow the user to do aperture and optimal photometry, automatic source detection, contouring, arbitrary region analysis, celestial coordinate readout, calibration and modification, grid overlays, blink comparison, image defect patching and the ability to connect to resources available in on-line catalogues and archives. An example of GAIA in action is shown in Figure 12


Figure 12: The GAIA interface.

A full discussion of GAIA’s capabilities can be found in SUN/214.