giftopnm(1)                                                   General Commands Manual                                                  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 oth-
       erwise, 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 out-
       put.

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)