Log message:
viewer  is an OpenGL based stereo pair viewer and aligner.  At present it
only accepts images in the PPM image  format but work is in progress to
allow use of other image types.  viewer is known to  work  on  various
systems,  including Linux and OSX, but should work on anything with OpenGL
and a compiler. Besides being useful as a stereo  pair  viewer it  is
also  possible  to  view  a  mono image and easliy pan/drag around within
the image.