If you don't get experienced copy-write lawyer on this you will lose no matter how much in the right you are. Believe me I've been there!
Great advise on this thread , do it or drop it.
Yes, great advice here, unfortunately most of it seems to be contradictory and up for debate- many facts, an equal amount of opinions- and don't get me wrong, I'm glad we're having this conversation- but the water is muddied, and I'm not certain of anything except what seems to be universally agreed upon:
Register the pics, and get a lawyer.
This really sucks, because I don't have the time, money, nor inclination for interstate travel and potentially spend thousands of dollars just to "make a point". And supposing I win? It looks like I'm responsible for making sure that I collect on the money.
Me: I'd like my money now. You're using my work without permission.
Me: I'd like my money now. I won the court case.