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)