From: jf_avon@citenet.net (Jean-Francois Avon (JFA Technologies, QC, Canada))
Date: Mon, 15 Apr 1996 07:40:29 +0800
To: cypherpunks@toad.com
Subject: Infrared photography
Message-ID: <9604142026.AA16940@cti02.citenet.net>
MIME-Version: 1.0
Content-Type: text/plain


>No, Clay, I did not say that the flesh RADIATED near IR. (it does, but only 
>a very tiny amount.)  The identification system I describe would probably 
>use 940 nm IRLEDs to illuminate the face, and a silicon CCD detector to pick 
>up the images.  Or it would use ambient near-IR, perhaps from the sun or a 
>tungsten filament or fluorescent lighting, along with an IR filter to ensure 
>that the CCD camera picked up only the IR bands of interest.  It would be 
>easy to check out the results:  Put such an IR-passing filter in front of a 
>CCD-based camcorder, and take a picture of somebody.
>
>Incidentally, this simplicity shows the flaw in using this kind of system as 
>an identifier:  Since people's faces are usually visible, and can be 
>photographed in the near-IR surreptitiously, it isn't clear how to prevent 
>faking a face which appears to have the same IR signature and pattern.

I remember in a booklet from Kodak on their Ektachrome IR film, there was a
picture
of a forearm where all the veins were made clearly visible.  This film is near 
infrared (if I remember, the red color on the film corresponds to around
1100 nm).

Veins and artery identification might be possible, maybe, since fingerprint
identification is possible.  A friend of mine developped a quite functionnal 
algorithm doing just that in the late eighties.  OTOH, the blood vessels
patterns are probably much more constant, from individual to individual,
than fingerprints.  Just correct me if I am wrong.

JFA


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