SAOimage (pronounced S-A-0-image) displays astronomical images in the X11
window environment. It was written by Mike Van Hilst while he was at the
Smithsonian Astrophysical Observatory (SAO) in 1990 and is now maintained by
Doug Mink also at the SAO.

Online help and documentation are on the webpage.

Image files can be read directly, or image data may be passed through a
named pipe (Unix) or a mailbox (VMS) from IRAF display tasks. SAOimage
provides a large selection of options for zooming, panning, scaling,
coloring, pixel readback, display blinking, and region specification. User
interactions are generally performed with the mouse, but keyboard
alternatives are often available.

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.

WWW: http://tdc-www.harvard.edu/software/saoimage/