A traveler has his face scanned at Washington Dulles International Airport. (Lori Aratani/Washington, D.C.)

With much fanfare, officials on Thursday unveiled a new system that eventually will replace boarding passes with facial scans for international travelers at Washington Dulles International Airport.

Instead of pulling out their passports and handing over a boarding pass, travelers will instead have their faces scanned. That photograph, shot by an iPad mounted on a stand, will then be matched with a collection of photos maintained by the U.S. Customs and Border Protection agency. If the photos — from passports and visa applications — match the one taken at the gate, the traveler will be cleared to board.

"CBP and our airport and airlines partners are redefining travel by using biometric technology to add convenience, efficiency and security to international arrivals and departures,” CBP Commissioner Kevin K. McAleenan said at the event, which included a demonstration of the new technology.

Currently, passengers still have to have their passports checked before they have their faces scanned, but airport officials are hoping to move to a system where the face scan is all that is needed.

Biometrics — particularly facial scans — are quickly becoming a popular alternative for verifying the identity of travelers moving through U.S. airports. Dulles, which developed the technology in-house, is one of several airports using scans in hopes of speeding the exit and entry process.

But civil liberties groups and privacy advocates fear that the technology is too intrusive and could be misused if it falls into the hands of the wrong people.

The technology is already being used by two international carriers at Dulles — SAS and Air France-KLM. On Thursday, airport officials hosted a demonstration of the technology on flights bound for Copenhagen and Amsterdam. United Airlines is also using the technology on select international flights.

Here's how it works.

Travelers stand in front of the machine. If the image shot by the iPad is a match, the screen will turn green, and they'll be permitted to board:

U.S. citizens can opt out of being photographed, but non-U.S. citizens are required to have their pictures taken. Images of U.S. citizens are held for 12 hours and then discarded. Travelers who declined to have their faces scanned will have their identity confirmed manually.

This post has been updated to note that United is also using facial scans to board some of its international flights.