Hmmm... Ok, I think we can close this votation. Except for Doug and myself, it seems obvious that I should keep the corrected one and that's what I gonna do!

@hotracer2: sorry, I installed photFiltre in the froggies' language but here are the 5 steps of what I did:

-first, add an empty area on the side of the picture where you have to drag...
-Select the entire picture
-Click on the contextual menu (right click) on "transformation-->distorsion"
-Drag the upper left corner
-Clik on "valid"

And that's it!

@Nilla: you can find that stuff at photoFiltre.com.

Thanks a lot to all of you!