Sir Lulzalot
Sergeant Knight at Arms

So a local business near me offers a service to make posters from images you give them for a few bucks and I am excited. So I want to make a poster from this but it is part of the portfolio of Art Streiber, who is a photographer. My question is is it legal under copyright laws and all that for me to make a poster from his picture and slap it on my wall? And to build further upon this would it be fine if I did the same thing for movies, bands, etc. This is just for my own decoration, I'm not going to sell it, modify it (aside from resizing it of course) or use it for other purposes. I can't find anything on the internet about this sort of ****.
Also, would I be able to get away with making that picture into a 27"X40" or something of similar size to preserve the aspect ratio without drastic pixelation?
Also, would I be able to get away with making that picture into a 27"X40" or something of similar size to preserve the aspect ratio without drastic pixelation?