Originally Posted by portiaeliot
When I got to just before the gate, the barcode was scanned (obviously an encoding of my photo), my photo popped up on the checker's monitor screen, and I was OK for the gate area (for an internal UK flight).
Just for clarification, the barcode is not an encoding of your photo. The barcode number is associated with the photo that is stored as a file on their computer. Scanning the barcode is just another way of retrieving the file. Cruise ships do this when you embark/disembark at the ports of call. They just use your room key instead of a barcode.