This is a difficult question. I think the copyright for images is something like the life of the artist plus 70 years but I guess many works aren't attributed to a known artist. You really need to see a lawyer who specializes in copyright law to answer you question otherwise you may find yourself being sued. There are a lot of great sites that will sell vintage images as framed posters. What they do about the copyright aspect is a very good question though ...It would be a good idea to find out more.