Path: utzoo!attcan!uunet!aplcen!haven!udel!udccvax1!cygnus
From: cygnus@vax1.acs.udel.EDU (Marc Cygnus)
Newsgroups: comp.graphics
Subject: Re: Color scanning from B&W scanner problem
Summary: speaking from experience not conjecture
Keywords: Wratten filters...
Message-ID: <5445@udccvax1.acs.udel.EDU>
Date: 8 Jan 90 07:49:41 GMT
References: <720004@hpvcfs1.HP.COM> <1941@hydra.riacs.edu> <5442@udccvax1.acs.udel.EDU> <5443@udccvax1.acs.udel.EDU> <1990Jan7.155917.29080@ux1.cso.uiuc.edu>
Reply-To: cygnus@vax1.acs.udel.EDU (Marc Cygnus)
Followup-To: comp.graphics
Distribution: na
Organization: The Lab Rats
Lines: 32

In article <1990Jan7.155917.29080@ux1.cso.uiuc.edu> mcdonald@aries.scs.uiuc.edu (Doug McDonald) writes: <regarding my posting about Kodak Wrattens>
>
>The Wratten filters mentioned previously are certainly NOT right
>for using in such a scanner. (In fact, they are probably not right
>for use in front of a camera, for photographing general subjects.
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>They are TOO narrow. They are for PRINTING use, or for doing color
>separations from three or four color printing or color photos.)
>For that you need bigger filters, and ones with higher transmission,
>due to the double pass nature. The theatrical gels are indeed
>available in suitable colors, and are available in big sizes.
>
>Doug McDonald

Don't use the mentioned filters with scanners - you're right, as I noted in
my second posting (I wasn't thinking about scanning when I posted the first
article - I was thinking about imaging from a video source).

But these filters _are_ correct for use "in front of a camera", or rather
in front of a digitiser. I'm speaking from experience here. I don't usually
invest large amounts of money in things that don't work. Let me reiterate that
the filters I named *are excellent for digitising colour* if you're using
a three-pass approach and a videocamera that behaves properly (either a colour
cam or a b/w cam that's sensitive more or less equally to the primaries).

					-marcus-

-- 
-----------------------------------------------------------------------------
"Opinions expressed above are not necessarily those of anyone in particular."
      `...but do YOU own a   |   ARPA: cygnus@vax1.acs.udel.edu
       homemade 6ft Tesla?'  |   UUCP: {yourpick}!cfg!udel!udccvax1!cygnus