@darren1228, lamination doesn't exactly remove the folds, the process simply conceals them, but if you look closely, you'll still be able to see the folds. But I guess it is the best solution here. Well, that and ironing the poster. If you opt for the second one, though, you need to have a cloth to cover the poster's surface, so that the hot iron doesn't make direct contact with the poster. Because some posters have been laminated (with very thin, lower grade film/plastic), if it comes into contact with something as hot as an iron, it might get burnt.