[IP] Re: face recognition flop why do I not believe this

[David Farber <dave@farber.net>]

Begin forwarded message:

From: Jeff Jonas <jeffjonas@us.ibm.com>
Date: July 26, 2007 1:54:14 PM EDT
To: dave@farber.net
Subject: Re: [IP] Re: face recognition flop why do I not believe this

Re: the comment on this thread -- "The only place I'm aware of facial  
recognition technology has met a measure of success has been in  
casinos, where the indoor controlled environment, the large number of  
cameras, basically stationary people and large security forces has  
resulted in usable results."

This is untrue. The only use case in the gaming industry I know of  
where facial recognition produces any useful results at all is when a  
surveillance room operator is already observing one specific person  
(because of some other trip-wire). When observing the person the  
surveillance room operator wonders if this face is in one of their  
mug books (e.g., The Griffin Book). Facial recognition enables them  
to take this person of interest and rank the mug book(s) into most  
likely look-a-likes.

I deployed the first such system that did this in the gaming industry  
back in 1996. Facial recognition is only marginally useful in this  
setting ... even when the subject of interest is preselected. And the  
bigger the mug book (watch list) the less useful facial recognition  
becomes.

So the notion of crowd scanning for bad guys in Vegas is entirely  
theatre.

Jeff Jonas
Distinguished Engineer and
Chief Scientist
IBM Entity Analytics
702.851.4697
JeffJonas@us.ibm.com
My blog: www.jeffjonas.typepad.com

David Farber <dave@farber.net>


David Farber <dave@farber.net>
07/26/2007 09:49 AM
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[IP] Re: face recognition flop why do I not believe this

Begin forwarded message:

From: Tom Goltz <tgoltz@quietsoftware.com>
Date: July 26, 2007 11:13:39 AM EDT
To: dave@farber.net
Cc: Brian Randell <Brian.Randell@ncl.ac.uk>
Subject: Re: [IP] face recognition flop why do I not believe this

At 08:20 PM 7/25/2007, you wrote:
> While the media got it wrong including the BKA's own president Jörg
> Ziercke - from a scientific perspective - these tests were a success
> With minimal human interference - false positive ratio was kept
> quite small - 0.1 percent

I don't believe it either.

Let's do the numbers.  If you have a stadium that holds 50,000
people, and you screen all of them with this technology, at a false-
positive rate of 0.1%, you'll get 50 false positives.  Assuming that
you detain all 50 for further investigation, and some significant
percentage of those people are members of parties who choose to
remain with the detained person, you'll be detaining and handling
between 100 and 200 people, most of whom will NOT be happy about the
situation they find themselves in.

The article goes on to suggest that the solution to this high false-
positive rate is to have a human double-check the match before
sounding the alarm.  The catch with this is that unless you're going
to design a fairly long gauntlet to run everyone through single-file,
you won't have TIME for a person to confirm the match before the
subject is lost in the crowd, unless you detain the suspect person
("sound the alarm").

What also is not mentioned is the false-negative rate associated with
this test.  In all of the realistic field tests I have seen to date
of face-recognition technology, the only way they've managed to get
the false-positive rate down to one-tenth of one percent was to set
the match requirements so tight that the false-negative rate
skyrocketed to such high levels that the system became essentially
useless.  The article claimed that both the false-negative and false-
positive rates were at 0.1%, but neglected to mention if both were
held to that low rate at the same time with the same settings.

Sporting events and mass-transit stations are particularly
problematic for computerized facial recognition technology, as
depending on the season you'll need to get your subjects to
cooperatively remove their hats, scarves, and sunglasses and all look
into the camera under consistent lighting conditions.

The only place I'm aware of facial recognition technology has met a
measure of success has been in casinos, where the indoor controlled
environment, the large number of cameras, basically stationary people
and large security forces has resulted in usable results.




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