The state of the art can be illustrated by some of the examples given by the US National Institute for Standards and Technology (NIST) in their presentation on testing biometrics.The linked article is an opinion piece by David GW Birch, a smart man and (unashamed) Ramones fan. The piece is very interesting and I encourage people to read the whole thing.
* A “1 in 1.6m” (that is, looking for one photo in a database of 1.6m photos) search on a 16-core 192Gb blade (about £25,000 worth of machine) takes less than one second (and the speed of such a search continues to improve). So if you have a database of a million people, and you’re checking a picture against that database, you can do it in less than second.
* The false non-match rate (in other words, what proportion of searches return the wrong picture) best performance is accelerating: in 2002 it was 20 per cent, by 2006 it was 3 per cent and by 2010 it had fallen to 0.3 per cent. This is an order of magnitude fall every four years and there’s no reason to suspect that it will not continue.
* The results seem to degrade by the log of population size (so that a 10 times bigger database delivers only twice the miss rate). Rather fascinatingly, no one seems to know why, but I imagine it must be some inherent property of the algorithms used.
A common refrain around here is: Identity management is about people, and Mr. Burch seems to get this, too. Towards the end of the piece, however, he seems to conflate privacy with anonymity.
Privacy in public is something we all take for granted. It is not difficult to assert an assumption of privacy covering observable public acts. If those acts are, however, assembled together by someone else and communicated to a third party, privacy can be greatly undermined.* The difference between having a private detective following you and not having one follow you makes for a useful illustration. Violation of public privacy has simply been a matter of resources and efficiency for the entirety of human history. Granted, modern technology stands to make undermining public privacy cheaper.
Anonymity in public is something different, and has probably only existed since the advent of rapid transit and the modern megalopolis -- and it's not necessarily a good thing.
We're all used to hearing about a "right to privacy" however overused the phrase may be. But it's unusual to hear someone posit a blanket, public right to anonymity, though in certain circumstances one undoubtedly exists: Political speech against oppressive regimes or religious confession, for example.
Mr. Burch subtly transitions to "online" anonymity when he begins the discussion of anonymity, but it's unclear how biometrics in general or facial recognition in particular stand to undermine online anonymity. Google's doing yeoman's work in this regard already.
Utilitarian thoughts:
It is possible that we value public privacy because it improves interpersonal relations among strangers.
Is it reasonable to view public anonymity with more skepticism because the opposite may be the case?
*UPDATE: The preceding two sentences were edited for clarity.
