Mr October is correct. They take your picture many times though-out the cruise. Each port, the formal dinners, contests etc etc...
Each picture runs like $7 for a 5x7. You can go during the cruise to the photo shop area and look for your pictures. If you like them you can purchase them if not, there is a bin to dispose of them. The cruise video is actually a pretty good deal. I think it was $25 or $29 for a DVD of your cruise. You are more than likely on it somewhere. We bought one on our last cruise because the video guy went with us on our Sting Ray encounter so we were on many shots. Also, he was able to take underwater footage that I could never have even dreamed of. So it was worth it for us. They start showing the footage on the TV in the cabin and at the photo desk, so you can look to see if you are on it before you by.
While the wife likes to buy the pictures, I just caution you to beware.. they add up fast.
Carnival Cruise Lines:
Fantasy 90, Celebration 95, Victory 05, Conquest 05, Spirit 6/06, Freedom 6/08, Holiday 7/08, Victory 6/09, Valor 9/09, Dream 6/10, Splendor 8/10,Conquest 8/11,Magic 11/11,Triumph 4/12,Spirit 7/12,Freedom 11/12, Triumph 2/13 - The fire cruise
NCL Dream October 2006, RCCL Mariner OTS June 2007