ftosh: convert float images to shorts, by RW Cox
Usage: ftosh [options] image_files ...
where the image_files are in the same format to3d accepts
and where the options are
-prefix pname: The output files will be named in the format
-suffix sname: 'pname.index.sname' where 'pname' and 'sname'
-start si: are strings given by the first 2 options.
-step ss: 'index' is a number, given by 'si+(i-1)*ss'
for the i-th output file, for i=1,2,...
*** Default pname = 'sh'
*** Default sname = nothing at all
*** Default si = 1
*** Default ss = 1
-nsize: Enforce the 'normal size' option, to make
the output images 64x64, 128x128, or 256x256.
-scale sval: 'sval' and 'bval' are numeric values; if
-base bval: sval is given, then the output images are
-top tval: formed by scaling the inputs by the formula
'output = sval*(input-bval)'.
*** Default sval is determined by finding
V = largest abs(input-bval) in all the input
images and then sval = tval / V.
*** Default tval is 32000; note that tval is only
used if sval is not given on the command line.