Sy Parrish: And if these pictures have anything important to say to future generations, it's this: I was here. I existed. I was young, I was happy, and someone cared enough about me in this world to take my picture.
Bill Owens: Sy, there's a 1000 other places where you can do your photos. There's no reason to come all the way down other than to fuck with me.
Sy Parrish: There's a very good reason. I calibrated that machine personally. It's the best mini-lab in the state.
Sy Parrish: Most people don't take snapshots of the little things. The used Band-Aid, the guy at the gas station, the wasp on the Jell-O. But these are the things that make up the true picture of our lives. People don't take pictures of these things.
Sy Parrish: The shutter is clicked. The flash goes off and they've stopped time, as if just for the blink of an eye.
Chosen answer: This is mentioned on the DVD commentary - it's deilberately open ended so one can interpret it as either it's Sy imagining what he wants to happen OR it's what really happened.
Neil Jones
As Neil Jones said, the ending is open for interpretation. However, I think there is reason to believe that Sy imagined the photo. It shows him and the family outside of their house, all looking happy together. Would they want to take such a photo with Sy after the incident at the hotel? And before the incident, they were probably not close enough with Sy that he would be in a photo taken at their home. Him and no other guests/visitors.