Re: Spectrophotometer measurements
Re: Spectrophotometer measurements
- Subject: Re: Spectrophotometer measurements
- From: Dan Reid <email@hidden>
- Date: Tue, 09 Jul 2002 17:00:22 -0600
On Mon, 08 Jul 2002 06:40:40 -0600, Andrew Rodney <email@hidden>
wrote:
>
From: Andrew Rodney <email@hidden>
>
Date: Mon, 08 Jul 2002 06:40:40 -0600
>
To: Joachim Euler <email@hidden>, Colorsync
<email@hidden>
>
Subject: Re: Spectrophotometer measurements
>
>
on 7/8/02 6:44 AM, Joachim Euler at email@hidden wrote:
>
>
> If you don't have another sheet of the very same paper at hand IMO any white
>
> paper will do. At least you'll be better off than without any backing.
>
>
So here's a twist. I have a few sheets of news print with targets printed.
>
At least I was able to get the backside clean (no printing). But newsprint
>
is kind of thin and I don't have any un-printed stock. What if I took 3 or 4
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identical sheets with the target, lined them up very carefully so there was
>
enough stock so the black couldn't be seen? The color patches would all line
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up so maybe this would be OK.
>
>
I guess I'll try measuring one sheet with white paper and several sheets
>
ganged up and see in MeasureTool how the two readings differ.
My understanding is the black table of a SpectroScan was designed to for
thin papers like newsprint. If you have the white table instead you
definitely need blank sheets OTW your L* will be off. On the flip-side
lighter colors and highlights may measure in accurately too because of the
black backing. I think the black table is based on an ISO standard, Henrik
may have words on this. Have you tried building a profile with a black
table?
Lining up printed sheets together may give you inaccurate measurements since
you're measuring through 2 or more thin papers will ink applied. I think the
saturation will be off. You should be able to easily *measure* this with the
Gretag MeasureTool as you've said.
I always, if given the option, use several sheets of the same paper taped to
the SpectroScan table. Best if they can send some blank sheet too instead of
kludging it.
--
Dan B. Reid
RENAISSANCE PHOTOGRAPHIC IMAGING
http://www.rpimaging.com | email@hidden
Toll Free: (866) RGB-CMYK
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