Not sure if this is the right section to ask this but here is my sitution. I am turning some of my works in to posters 24in x 36 in posters. The issue I am seeing is some of my backgrounds I purchased here at the market place, and although they are large they are jpg formats, there for resizing them up I lose the sharpness.

 

I was under the assumbtion if I made it a smart object in photoshop you could resize with out loss of quility but that doesnt seem to be the case all though its not to bad you an still see some pixeliation.

So I am looking for some solution to be able to use these backgrounds, with out losing quility one other Idea I had is trying to use the jpg in Adobe Illustrator but thinking I iwll still hit the same wall.

Again any suggestions other then make my posters smaller would be greatful :)