you can use Rasterbator. not what it sounds like. its a program that divides a picture into pages. so if you want a wall sized poster, the program would print out like 50 pages with each page being a part of the full poster. i made a coca-cola bg.
Rasterbator prints out your picture with dots. you can choose small,med,lrg size dots to make up your picture. there are other programs that dont use dots. u look it up yourself.rasterbator link. in the end it looks real nice. trust me.
if you guys got nothing to do. rasterbate your wall. fun project. you can cover your wall with a picture of a p. bass if you wanted to. thats what ima do but with a diff fish.