UNEXP(1)                                               UNEXP(1)





NAME
       unexp - Convert "exponential" files into normal files.

SYNOPSIS
       unexp  [ -m maxval ] [ -o outfile ] [ -p ] [ -s ] [ -v ]
       infile

DESCRIPTION
       Unexp Converts a file of  "exponential"  floating  point
       values  into  an  RLE(5)  file containing integer valued
       bytes.  Exponential files have N-1 channels of eight bit
       data,  with the Nth channel containing a common exponent
       for the other channels.  This allows the  values  repre-
       sented by the pixels to have a wider dynamic range.

       If  no maximum value is specified, unexp first reads the
       RLE file to find the dynamic range of  the  whole  file.
       It  then  rewinds  the file and scales the output to fit
       within that dynamic range.  If a maximum value is speci-
       fied,  unexp  runs  in  one  pass, and clamps any values
       exceeding the maximum.

       Files containing exponential data are expected to have a
       "exponential_data"  comment;  unexp  prints a warning if
       such a  comment  doesn't  exist.   An  exponential  file
       should  be  unexp'ed  before attempting to use any tools
       that perform arithmetic  on  pixels  (e.g.,  rlecomp(1),
       avg4(1),  fant(1),  or  applymap(1))  or  displaying the
       image.

       Unexp does not allow piped input.  The infile must be  a
       real file; the special filenames described in urt(1) are
       not allowed.  ("-" does work, as long as  the  input  is
       coming  from  a  real  file; this is of minimal utility,
       therefore, as typing unexp -  <foo.rle  is  harder  than
       typing unexp foo.rle.)

OPTIONS
       -m maxval
              Specify  the maximum value (i.e., the data in the
              file is assumed to be in  the  range  0..maxval).
              Only  the conversion pass is executed, and values
              found exceeding the maximum are clamped.

       -o outfile
              If specified, the output will be written to  this
              file.   If outfile is "-", or if it is not speci-
              fied, the output will be written to the  standard
              output stream.

       -p     Print the maximum value found during the scanning
              phase

       -s     Just scan the file to  find  the  maximum,  don't
              generate any output.

       -v     Verbose  mode,  print  a  message to stderr after
              scanning or converting every hundred scanlines.

SEE ALSO
       float_to_exp(3), urt(1), RLE(5).

AUTHOR
       John W. Peterson

BUGS
       Unexp is provided because of the lack of floating  point
       or extended precision RLE files.

       The  -v  flag  is  a historical relict from the slow CPU
       days.



1                       November 8, 1987               UNEXP(1)
