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)