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Re: Are GPLed .gifs legal at all ???

On Thu, Jul 13, 2000 at 03:48:56AM +0200, Tomasz Wegrzanowski wrote:
> > > If the GIFs were created with unlicensed tools, then the author of the
> > > images might be in violation.  If they are viewed with unlicensed tools,
> > > then the viewer might be in violation.  The author/distributor of such
> > > tools might be in violation.  In all cases, it's the tool that is
> > > infringing the patent, not the data.
> > 
> > There is no patent on LZW decompression.  Only compression.
> One more word before everyone will miss my point.

Modifying a GIF involves decompressing it into a pixmap, changing the
pixmap, and writing over the GIF with a new one.  Provided you do not LZW
compress the new one, you're okay.  Unless of course the program cannot
read a non-LZW GIF file (some programs like at least the last version of
zgv I used couldn't read the output of libungif), in which case you cannot
freely modify its GIFs..

> GPL requires people to whom you redistribute a file
> to be able to modify and redistribute it.
> But they can't modify .gifs they got, because of
> patent problems.

But you CAN modify GIFs, you just cannot use LZW compression on the

> GPL says. that if, due to patent problems, you
> can't meet all licence's critaria, you can't distribute
> GPLed file at all.
> So it seems to me that you can't distribute GPLed LZWgifs at all.
> ( so Debian probably has severe legal problem because several of
>   packages containing .gifs are GPL/LGPL )

It seems to me you're looking to start a crusade against free software
using GIFs just because you don't like UniSys.  Find something worthwhile
to crusade against - the UniSys patent on LZW is almost up anyway and even
if that weren't the case, there are only a small handful of programs which
use GIFs that cannot read one that is uncompressed.

Next thing I know you'll be filing bugs against Quake because in OpenGL it
saves screenshots as Targa (though uncompressed) and at least one major
variant of Targa uses LZW.  Don't even think about it - I'd close the bug
without a second thought.

There is no legal problem here.  There might be a political problem, but I
really don't care about that.

Joseph Carter <knghtbrd@debian.org>               GnuPG key 1024D/DCF9DAB3
Debian GNU/Linux (http://www.debian.org/)         20F6 2261 F185 7A3E 79FC
The QuakeForge Project (http://quakeforge.net/)   44F9 8FF7 D7A3 DCF9 DAB3

<Delenn> I wouldn't make it through 24 hours before I'd be firing up the grill
         and slapping a few friends on the barbie.
<spacemoos> Why would you slap friends with barbies, thats kinda kinky

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