Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!rutgers!network!sdcsvax!ucsdhub!hp-sdd!hplabs!hpfcdc!hpfcdj!brian
From: brian@hpfcdj.HP.COM (Brian Rauchfuss)
Newsgroups: comp.graphics
Subject: Re: Color desktop scanners (a technical discussion begins)
Message-ID: <17400003@hpfcdj.HP.COM>
Date: 10 Aug 89 14:32:41 GMT
References: <1869@ucsd.EDU>
Organization: Hewlett Packard -- Fort Collins, CO
Lines: 18


   Using three monochromatic lasers has a problem: only
colors containing the three wavelengths wavelengths of 
the lasers would show up.  A color which only reflects
a narrow bandwidth in-between the colors of the lasers would
show up as black!  (For example, a monochromatic yellow would
be totally missed by monochomatic red light and monochomatic 
green light).

   What you need for the scanner is relatively broad-band light
(using filters on white light maybe) so that you can determine 
intermediate colors by measuring low level reflections of two 
input lights.

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Brian Smokefoot              "I never knew I could shape my life
brian@hpfcbdr.HP.COM         like the artist paints his dreams
                             on a canvas." - Minor Detail