Pamtopfm User Manual(0)                 Pamtopfm User Manual(0)



Table Of Contents


NAME
       pamtopfm  -  Convert Netpbm image to PFM (Portable Float
       Map)


SYNOPSIS
       pamtopfm [-endian={big|little}]  [-scale=float]  [image-
       file]

       All  options can be abbreviated to their shortest unique
       prefix.  You may use two hyphens instead  of  one.   You
       may  separate  an  option  name and its value with white
       space instead of an equals sign.


DESCRIPTION
       This program is part of Netpbm(1).

       pamtopfm reads a Netpbm image (PNM or PAM) and  converts
       it to a PFM (Portable Float Map) image.

       The  PFM (Portable Float Map) image format is a lot like
       PPM, but uses floating point numbers with no  maxval  to
       achieve  a  High Dynamic Range (HDR) format.  That means
       it doesn't have a concept of absolute color and  it  can
       represent  generic  light  intensity  information rather
       than just visual information like PPM does.   For  exam-
       ple,  two pixels that are so close in intensity that the
       human eye cannot tell them apart are not  visually  dis-
       tinct,  so  a visual image format such as PPM would have
       no reason to use different sample values for them.   But
       an HDR format would.

       There  are  details  of the PFM format in the PFM Format
       Description (1).

       USC's HDRShop program  and a program  called  Lefty  use
       it.

       pamtopfm  creates  a color PFM image if its input is RGB
       (PPM) and a non-color PFM otherwise.

       Use pfmtopam(1)toconvertaPFM image to Netpbm format.



OPTIONS
       -scale=float

              This specifies the scale factor of the PFM image.
                   Scale  factor is a component of the PFM for-
              mat.
                   Default is 1.0.


       -endian={big|little}

              This specifies the endianness of the  PFM  image.
              The samples
                   in the raster of a PFM image are 4 byte IEEE
              floating point
                   numbers.  A parameter of  the  IEEE  format,
              and therefore the PFM
                   format,  is  endianness,  i.e.  whether  the
              specified bytes are
                   ordered from low addresses to high addresses
              or vice versa.

              big means big endian -- the natural ordering;
                   little   means   little-endian,  the  Intel-
              friendly ordering.

              Default is whichever endianness  the  machine  on
              which pamtopfm
                   runs  uses  internally, which results in the
              faster execution.




SEE ALSO
       Netpbm(1), pfmtopam(1), pam(1)


HISTORY
       pamtopfm was added to Netpbm  in  Release  10.22  (April
       2004).



netpbm documentation     10 April 2004  Pamtopfm User Manual(0)
