Re: was: Brightener in Epson Premium Glossy
Re: was: Brightener in Epson Premium Glossy
- Subject: Re: was: Brightener in Epson Premium Glossy
- From: Graeme Gill <email@hidden>
- Date: Mon, 30 Sep 2002 15:37:11 +1000
neil snape wrote:
>
I've always wondered about the relation if any about fluorescence and
>
optical brighteners.
Optical brighteners are dominantly fluorescent materials. I think
to some degree there are also simple dyes or pigments added to
reduce mid wavelength reflection levels, but the fluorescent
component is also known as Fluorescent Whitener Additives. In
researching this a few months back, I came across some
interesting articles on the web, and one good one was
<
http://mitglied.lycos.de/whiteness/BrightnessReview.pdf>.
One interesting correlation is that the cheaper the paper
(ie. more natively yellow and low reflectance it is), the
more whiteners will be added to make it look blue (subjectively
white). Office laser printer paper is a great example.
>
What are the effects, how does a spectro non-uv or uv
>
see this and what bias is the key factor to how it is seen.
The paper touches on what effect using a UV filter has on
measurement (enough to convince me that UV filters are
useless when trying to create color profiles, as opposed to
measuring paper whiteness).
There is no doubt that the presence of UV brighteners makes the
appearance of a print more dependent than ever on subtle
characteristics of the light source.
I think the simplest way of avoiding these sorts of problems in proofing,
is to try and match the whitener content of the proofing paper to
that of the target. Even if the different effects the instrument illumination
has on the whitener compared to the viewing illumination, is fully
compensated for in the profiling software, any differences in the
UV level of the actual viewing conditions can cause noticeable shifts
in color.
>
Do the inks
>
themselves filter the reflected light in a way that influences the paper
>
base (unprinted)?
I'm not sure what you mean by this question. Can you re-phrase it ?
Graeme Gill.
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