OSMC Skin. Poster size

Hi all,
This is my first post here. I think OSMC is awesome and I’m using the default OSMC Skin. I use .nfo to provide information and it’s working great. Nevertheless, I have a problem with poster sizes. Unfortunately not all my images have a 1:1.5 ratio so the aspect of the movies home page is awful. Is there any way to stretch or scale those images? What xml file should I modify in order to get it?

Thanks a lot in advance!