Videoprojector distorsion

I have applied a wide-angle lens to a videoprojector to increase the greatness of the projection without getting further too much me.
but the projection is deformed as in the figure under.

http://www.dotzero.it/difetto.jpg

how can I correct the exit of the renderer so that to correct the distorsion?
thanks.

maybe this quickhack helps.

map the texture onto a part of a sphere might be more correct though…

SphericalDeformXY.zip (2.3 kB)

spectacular.
just what served me, thanks thousand.