SAOImageDS9 is an astronomical imaging and data visualization
application. DS9 supports FITS images and binary tables,  multiple
frame buffers, region manipulation, and many scale algorithms and
colormaps. All versions and platforms support a consistent set of GUI
and functional capabilities.  DS9 supports advanced features such as
2-D, 3-D and RGB frame buffers, mosaic images, tiling, blinking,
geometric markers, colormap manipulation, scaling, arbitrary zoom,
cropping, rotation, pan, and a variety of coordinate systems.
Furthermore, the application is stand-alone and requires no
installation or support files.  The GUI for DS9 is user configurable.
GUI elements such as the coordinate display, panner, magnifier,
horizontal and vertical graphs, button bar, and color bar can be
configured via menus or the command line.