The SFD (SXT Full-frame Desaturated) images use a logarithmic compression
in order to save the data as byte type. The decompression algorithm
is data_out = 
. The routine SFD_DECOMP will
do this decompression for you. Beware: the output are floating type numbers
and therefore, require four times as much memory.
IDL> data_out = sfd_decomp(data_in)