If it wasn't the registered owner of the vehicle at the wheel, you're in luck.
At least in California, they can't give a car a ticket for running a red light, they have to give it to the person at the wheel.
Whoever receives the ticket, assuming it isn't them in the photo, should either contact their local police department that deals with traffic violations, and they'll dismiss it on the spot... usually.
If not, just go to court, when it comes time to talk to the judge, they need to simply say, "Thats not me in the photo". If it isn't, the judge has to dismiss it. In spite of what they claim, they can't force you to even speculate who was at the wheel or why.
However, once dismissed, the police/traffic people may review drivers license photos of other people who share the registered drivers address... if a face matches, they can send a ticket to them.
by the way, this happened to me (driving girlfriends car, got a photo at a red light... she went to court, said it wasn't her, and dismissed without question).
But if I hadn't run across this website, I wouldn't have known:
Highway Robbery: Illegal Red Light Cameras