Path: utzoo!mnetor!uunet!mcvax!ukc!stc!root44!hrc63!hughes
From: hughes@hrc63.co.uk (Andrew C. Hughes)
Newsgroups: comp.graphics
Subject: Re: Color scanning of negatives
Message-ID: <497@hrc63.co.uk>
Date: 17 Feb 88 15:14:26 GMT
References: <333@inuxf.UUCP>
Organization: GEC Hirst Research Centre, Wembley, England.
Lines: 19

In article <333@inuxf.UUCP>, matt@inuxf.UUCP (Matt Verner) writes:
> I am looking for references that indicate the proper way to convert
> 'negative' RGB information to 'positive' RGB.  In other words if
> I take a film negative and scan it into an image using a color
> scanner what formula do I use to convert the image into a positive,
> properly color balanced, image?  The key here is proper color balance.
> 
All photographic negative material has a strong colour cast (usually orange)
which would have to be filtered out in your conversion. It is also based on
CMY (Cyan, Magenta, Yellow) filtration and so you would need another
conversion factor to get RGB values. I believe that an algorithm to do this
conversion was recently posted to this group so you might be able to find it.

Andrew Hughes
GEC-Marconi Research Centre,
Chelmsford, UK.

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