Re: On the effect of florescence
Re: On the effect of florescence
- Subject: Re: On the effect of florescence
- From: Roger Breton <email@hidden>
- Date: Tue, 01 Mar 2005 20:26:04 -0500
> Using the UV Cut filter puts all the
> paper measurements to the same reference point.
>
> Robin Myers
Please excuse my ignorance but isn't there a limit to which a UV filter can
'adequately' correct measurements in substrates with varying amount of FWA?
You write that it 'puts all the paper measurements to the same reference
point'. Fine. But wouldn't you rather say that it correct paper measurements
by the same fixed amount? I fail to see what 'a fixed reference point' would
be.
Let's take the case of printing papers or inkjet papers or office
photocopying or laser papers. As you know, some of these papers are very
close to neutral, many european litho paper, I'm told. Inexpensive litho
papers (coated gloss #3) have a moderate amount of FWA, with b* between -2
to -5. I've personally seen some inkjet papers with b* = -9 ! That is quite
fluorescent, if you ask me. But, in this context of wildy differing amount
of FWA in papers, I have difficulty to conceptualize that a fixed UV cut
filter "will put all the paper measurements to the same reference point'?
You don't mean to say that a UV cut filter will bring a paper with b* = -9
or a paper with b* = -4 or -5 or -2 to the b* = 0 ? In my limited
understanding of physics and metrology, I would tend to think that the UV
filter on the Spectroscan will 'substract' a constant amount of visible
light evergy over a fixed wavelength interval but that this fixed
substraction (please excuse my poor terminology) will not be the right
correction for all amounts of FWA in every paper that comes along.
Therefore, I would venture to say, there is some component of FWA that will
not be corrected but the filter. And we'll still have problems with gray
balance in profiling.
Regards,
Roger Breton | Laval, Canada | email@hidden
http://pages.infinit.net/graxx
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