It's not just smiles that are forbidden on photos for Europe's forthcoming e-passports -- oversized glasses and headwear will also be out.
According to a specification from the International Civil Aviation Organisation, citizens of the 188 member countries will have to respect strict rules before getting into the photo booth -- including instructions to stop smiling too much, because it will affect the soon-to-be-introduced digital facial recognition systems.
Recently, the UK government put its head above the parapet by publishing instructions on the matter. The passport service has stipulated that it will only allow photos in which the face of the passport holder is shown in its entirety and looking straight at the camera, with a neutral expression and a closed mouth.
The directive will come into force in March 2005 in the UK and will form part of the Europe-wide drive towards biometric passports.
While biometrics can use a person's fingerprints, iris or face to identify them, Europe has opted for the face as its favourite biometric for identity documents.
So how exactly does smiling hamper the facial recognition systems? "The smile alters the position and the structure of the eyes and nose, which are the three principal identification points which characterise a face," according to Thales Security and Supervision, a subsidiary of the French security and defence technologies group,
"The haircut or beard have less effect on facial recognition," it continues, adding that facial recognition techniques currently use an average of 128 points of comparison.
Europe looks set to follow the UK's decision on the matter. Every country planning to introduce a biometric passport -- and therefore all the states of the EU -- will have to publish similar directives.
The need to keep a neutral expression is clearly written in the reference document that will be used as the foundation for all such processes. The document in question is appendix A of "the biometrics deployment of machine-readable travel documents", published in May by the ICAO.
The appendix gives clear instructions on how to take a photo that can be used for biometrics. As well as not smiling, the ICAO recommends looking straight at the camera, keeping eyes open, not having hair over the face, not wearing tinted sunglasses, not wearing hats or religious head coverings that obscure any part of the face from the bottom of the chin to the top of the forehead and being alone in the picture.
While wearing a hat or a baseball cap is forbidden, a headscarf that covers just the wearer's hair is permissible. In France, the law states that photos for identity purposes must never be taken with any form of headwear -- religious or not.
The first biometric passports will be phased in progressively from 2005. Biometric passports and visas are intended to improve authentication of the documents themselves and not, at least in the short term, to identify potential terrorists by means of automatic comparison between the individual and a blacklist of people stored on a distant server.
That kind of procedure is predicted in a second phase, when the technology will be more efficient, by using 3D comparisons and skin-texture analysis.
In 2005, European visas and passports will have to carry an RFID-type chip containing the digitised facial image of the rightful holder. When passing through customs, the document will be scanned by a reader, which will compare the image on the chip with the photograph on the document.
The stored image and the passport photo will be compared to the individual in person, either by customs officials or by technology.