giftopnm

 

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 giftopnm(1)                                           giftopnm(1)
 
 
 
NAME
        giftopnm - convert a GIF file into a portable anymap
 
SYNOPSIS
        giftopnm [--alphaout={alpha-filename,-}] [-verbose] [-com­
        ments] [-image N] [GIFfile]
 
 
DESCRIPTION
        Reads a GIF file for input, and outputs portable anymap.
 
        If you have an animated GIF file, you can extract individ­
        ual  frames  from  it with gifsicle and then convert those
        using giftopnm.
 
        If the image identifies  a  transparent  background  color
        (i.e.  a  color  that  a user of the image should treat as
        transparent in the event that the image is  overlaid  over
        another), giftopnm issues a message telling you what color
        that is when you use the -verbose option.   You  can  then
        use  ppmcolormask  to  create  a  PGM  file representing a
        transparency mask and use that PGM file with other  Netpbm
        programs to effect transparency.
 
 
 
OPTIONS
        --alphaout=alpha-filename
               giftopnm creates a PGM (portable graymap) file con­
               taining 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 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 pre­
        fix.
 
 
 BUGS
        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.  The patent expires in 2003.
 
        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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