Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!sun-barr!apple!oliveb!orc!orc.olivetti.com!TEG
From: TEG@orc.olivetti.com
Newsgroups: comp.graphics
Subject: Re: color scanning
Message-ID: <48754@ricerca.UUCP>
Date: 6 Dec 89 04:56:45 GMT
Sender: news@orc.Olivetti.Com
Reply-To: TEG@orc.olivetti.com ()
Organization: Olivetti Research Center, Menlo Park, CA
Lines: 21

You definately cannot do color scanning (using color filters)
with a hand scanner.  The problem is that hand scanners use
a narrow spectrum of light (usually visible red or green)
to detect the image.  If you put a red filter on a hand scanner
with red light source you would get a blank scan.  Some
photocopiers used bluish or greenish light sources so it was
known to many a secretary not to try copying documents written
in green or blue ink...

Most of the color scanners use multiple light sources (ie. RGB)
with one scanning element (and multiple passes - 1 for each color).
Color filter scanning works well with b/w t.v. cameras and a
frame grabber board.  Many setups of this type were sold to amiga
users.  It takes a while to flip the "color wheel" between scans
and your subject must stay still.


Tom Griner  Systems Administrator - Olivetti Research Center  frames 2 /dev/fb
uunet!wyse!decwrl!pyramid!oliveb!TEG  TEG@ORC.Olivetti.Com  flames 2 /dev/null
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