If you don't understand what are patent problems : http://eupat.ffii.org/patents/effects/ipix/index.en.html
Helmut Dersch , a mathematics and physics professor in a German University created algorythms to stitch photographs into a panorama view, and proposed it as a free software (panotools) ! He did it before than a USA company register patents for such kind of program ! He had to remove his free software from his public university site to get protected from legal action ! Some panorama fanatics fortunately provided copyes of those tools on their own site and we could use them for years... it was the begining of Hugin (a graphical interface to use these algorythms) and PTviewer The libpano13 library which is proposed by Mandriva is limited in its use not to infringe the USA law (we couldn't build a 360° panorama with this library!). PLF repo contains an unlimited version of this library . (same name but not same "make" configuration : have a look on the spec file !) that infringes the USA law ! The creator of a software can be prosecuted on the basis of patents even if they were registered later !!!! Being careful doesn't mean accepting this, but being aware of this !