Mrs A and I are planning a trip (NFI) to an undisclosed location and need to have our passports renewed, since in the last few years they have been used for Canada only. So, off to COSTCO we went for the 2X2 photos required with the renewal application. The COSTCO photog. warned us NOT to smile or show any teeth during the shoot, since people have had their photos rejected by State Department allegedly for just that--being happy!
Facial Recognition technology is something I actually know something about, having worked on a project featuring that at SRI.
So be warned: no smiling or teeth showing on passports!!!