iraf.net

When I load an image into ds9 from iraf with display, the background (area larger than the image) is always white. This does not depend on the ds9 invert colormap setting nor 'background color/Blank/Inf/NAN preferences.

Is there a way to force the background to be black?

If I load a FITS image directly into ds9 (using the File/open menu option, for example) then the background behaves as expected.

So what is 'display' loading into ds9 outside the image area? How can it be changed?

Trying to minimize the amount of white staring me in the face.

thanks, Pat

The answer may depend on your DS9 version, and saord@cfa.harvard.edu would be the place to ask about specific DS9 options.

However, the image being displayed by IRAF is centered in the framebuffer defined by the 'stdimage' variable. For the standard 512x512 dev$pix image this means that if stdimage=imt800 the image is centered in an 800x800 frame where the area outside the image has zero values and is rendered as black. Now if you stretch the DS9 window so the display area is bigger than that, then the area outside of the *frame buffer* is white, but that's a matter of how DS9 renders the frame buffer and not how IRAF displayed the image. You can use a smaller frame buffer and/or turn on the 'fill' parameter to fill the frame buffer, but that won't eliminate the white area. To do that the only option I know of is to make the ds9 window smaller.

Of course, making the frame buffer insanely huge would also work in most cases, but you may find that having to zoom in to a smaller image all the time is even more annoying.