giftopnm(1)

NAME

   giftopnm - convert a GIF file into a portable anymap

SYNOPSIS

   giftopnm [--alphaout={alpha-filename,-}] [-verbose] [-comments] [-image
   N] [GIFfile]

DESCRIPTION

   This is a graphics format converter from the  GIF  format  to  the  PNM
   (i.e. PBM, PGM, or PPM) format.

   If the image contains only black and maximally bright white, the output
   is PBM.  If the image contains more than those  two  colors,  but  only
   grays,  the  output  is  PGM.   If the image contains other colors, the
   output is PPM.

   If you have an animated GIF file, you  can  extract  individual  frames
   from it with gifsicle and then convert those using giftopnm.

   A GIF image contains rectangular pixels.  They all have the same aspect
   ratio, but may not be square (it's actually quite unusual for them  not
   to  be  square, but it could happen).  The pixels of a Netpbm image are
   always square.  Because of the engineering complexity to do  otherwise,
   giftopnm  converts a GIF image to a Netpbm image pixel-for-pixel.  This
   means if the GIF pixels are not square, the Netpbm output image has the
   wrong  aspect  ratio.   In  this case, giftopnm issues an informational
   message telling you to run pnmscale to correct the output.

OPTIONS

   --alphaout=alpha-filename
          giftopnm creates a PGM (portable graymap)  file  containing  the
          alpha  channel  values  in  the input image.  If the input image
          doesn't  contain  an  alpha  channel,  the  alpha-filename  file
          contains  all  zero  (transparent)  alpha  values.  If you don't
          specify --alphaout, giftopnm does not generate  an  alpha  file,
          and  if  the  input  image has an alpha channel, giftopnm simply
          discards it.

          If you specify - as the  filename,  giftopnm  writes  the  alpha
          output to Standard Output and discards the image.

          See pnmcomp(1) for one way to use the alpha output file.

   -verbose
          Produce verbose output about the GIF file input.

   -comments
          Only output GIF89 comment fields.

   -image N
          Output the specified gif image from the input GIF archive (where
          N is '1', '2', '20'...).  Normally there is only one  image  per
          file, so this option is not needed.

   All flags can be abbreviated to their shortest unique prefix.

RESTRICTIONS

   This  does  not  correctly handle the Plain Text Extension of the GIF89
   standard, since I did not have any example input files containing them.

SEE ALSO

   ppmtogif(1),       ppmcolormask(1),       pnmcomp(1),       gifsicle(1)
   <http://www.lcdf.org/gifsicle>, ppm(5).

AUTHOR

   Copyright (c) 1993 by David Koblas (koblas@netcom.com)

LICENSE

   If  you  use  giftopnm,  you  are using a patent on the LZW compression
   method which is owned by Unisys, and in all probability you do not have
   a  license  from  Unisys  to  do so.  Unisys typically asks $5000 for a
   license for trivial use of the patent.  Unisys has never  enforced  the
   patent  against  trivial users, and has made statements that it is much
   less concerned about people using the patent for  decompression  (which
   is what giftopnm does than for compression.  The patent expires in 2003
   / 2004, depending on the country.

   Rumor has it that IBM also owns a patent covering giftopnm.

   A replacement for the GIF format that does not require any  patents  to
   use is the PNG format.

                            13 January 2001                    giftopnm(1)

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Free and Open Source Software