Whatever works, ya know? Contests will usually state whether or not post work is allowed. If you're referring to the monthly challenges here, we don't have a policy, really, and it's just for fun, anyway. Even that could change too, though, because whoever wins, gets the right to make the rules for the following one. Most of my pictures have at least some postwork in them. Some have alot, and a few have none. Like I said, whatever works! Even "traditional" artists often use very much NON traditional techniques....