[IPOL discuss] Patents and IPOL code

Nicolas Limare nicolas.limare at cmla.ens-cachan.fr
Wed Apr 6 04:19:49 CEST 2011

> As far as I know, patents and free software are full incompatible.

Not exactly. webM[1] is patented and the implementation is distributed
under a BSD license.
-> http://www.webmproject.org/license/
This is possible because the patent owner (Google) decided not to
use the patent to restrict the distribution rights. So, to be exact,
patents restricting the distribution rights and free software licences
are in contradiction.

> If an algorithm is patented and its distribution isn't not legal then you
> can't change that fact by re-licensing it.

I agree.

> No free software license is applicable in that case.

The free software license will still be valid "where the patent
doesn't restrict the redistribution rights", ie in places where no
patent has been filed, or after the patent exdpiration (Hamilton-Adams
US patent 5629734 expires on Mar 17, 2015) or in countries (mostly
eastern africa and pacific islands) where no international patent
treaty has been ratified.
-> http://en.wikipedia.org/wiki/List_of_parties_to_international_patent_treaties

So, for me, putting a BSD license on a patended algorithm with a
patent warning means:

"Be careful before you download, use, modify and redistribute this
code. We know there is a patent, and this patent may restrict your
rights. We are not lawyers, the situation is different for every
country and changes over time, so it is your job to check you are not
doing something unlawful. If and only if you are free from any patent
restriction, then your can enjoy the BSD license terms".

Nicolas LIMARE - CMLA - ENS Cachan    http://www.cmla.ens-cachan.fr/~limare/
IPOL - image processing on line                          http://www.ipol.im/
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