This is a tricky question. The more intact a picture is, the more convincing it is as an original item. That said, many paintings are relined, reframed, cut down, cleaned etc. during their lifetimes, and somehow they retain their values. If you are in doubt as to whether your item is an original or a print, look at the surface under a magnifying glass. If the picture is comprised of tiny, regular dots, then it is definitely a print. Conversely, you may be able to see brushstrokes and texture under magnification that will indicate a painting.