Hi guys i have a quick question.. im sure it has been addressed before and sorry if it has... i am trying to make a photo collage using photoshop.. and after im done with it iam taking it somewhere to have it printed 16x20 .. my question is... what size image should i do it in photoshop? what resolution? if theres anything else i need to do so the quality comes out perfect when its printed that big..  thanks in advanced..