The data format used by the IMG library will normally be the Starlink
``Extensible N-Dimensional Data Format'' or NDF (described in
SUN/33), which is typically stored in files with a
.sdf extension. However, IMG can also access other
astronomical formats (such as IRAF, disk FITS
or FIGARO) and new ones can easily be added, so using IMG gives your
programs access to a wide range of astronomical data in a very
straightforward way (see §).
IMG can be used from the Fortran-77 and C programming languages and some familiarity with one of these is assumed, as is knowledge of the UNIX C-shell. If you want to use IMG from C then you should briefly study the earlier sections (which are Fortran specific, but nevertheless show the appropriate calling sequences and discuss more general issues) and then look at this later section.
IMG Simple Image Data Access