IRAF is the "Image Reduction
and Analysis Facility
". The main IRAF distribution includes a good selection of program
s for general image processing
, plus a large number of programs for the reduction and analysis of optical and IR astronomy
Other external or layered packages are available for applications such as data acquisition or handling data from other observatories and wavelength
regimes such as the Hubble Space Telescope
(optical), EUVE (extreme ultra-violet), or ROSAT
(X-ray). These external packages are distributed separately from the main IRAF distribution but can be easily installed. The IRAF system also includes a complete programming environment for scientific
applications, which includes a programmable Command Language scripting facility, the IMFORT Fortran
programming interface, and the full SPP/VOS programming environment in which the portable IRAF system and all applications are written.
This is a cut and paste
from the IRAF homepage, basically because they
explain what it is better than i can.
IRAF is freely available, but you proably
don't want to use it unless
you are doing astronomy in which case
you proabaly already have it.
IRAF has a command line interface which obeys
some UNIX commands but not others,
just to be paticullarly confusing.
For more information have a look at their hompage