pamtopfm

   Updated: 10 April 2004 Table Of Contents

NAME

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

SYNOPSIS

   pamtopfm [-endian={big|little}] [-scale=float] [imagefile]

   All	options	 can be abbreviated to their shortest unique pre-
fix. 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.

   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 Dynam-
ic 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 example, two pixels that are so
close in
   intensity   that  the human eye cannot tell them apart are not
visually
   distinct, 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 Descrip-
tion.

   USC's HDRShop program and a program called Lefty use it.  pam-
topfm creates a
   color  PFM image if its input is RGB (PPM) and a non-color PFM
otherwise.

   Use pfmtopam to convert a PFM image to Netpbm format.

OPTIONS

   -scale=float
	  This specifies the scale factor of the PFM image. Scale
factor is a
	  component of the PFM format. 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  or-
dered from low
	  addresses to high addresses or vice versa.
	  big  means  big  endian  --  the natural ordering; lit-
tle 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, pfmtopam, pam

HISTORY

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



Table Of Contents

     * NAME
     * SYNOPSIS
     * DESCRIPTION
     * OPTIONS
     * SEE ALSO
     * HISTORY

UNIX/Linux commands referenced on this page:

1. as
2. pfmtopam
3. convert
4. factor
5. addresses
6. which