Digital BW, The Print

I'm not so sure, the OBAs certainly change the apparent paper color, and
that is due to the UV excited fluorescence.
If the OBAs fluoresce, i.e. produce a new wavelength due to the UV content
in the illumination, they the paper color _does_ appear different to us.
Using the UV cut filter prevents any measurement of that effect.
Since the i1 has a single illuminant, IIRC, the fluorescence can't be
measured directly, but it can be inferred by looking at the shape of the
spectral curve.  If it is generally flat, with a hump in the blue, that
looks like OBAs.  With a UV cut filter, you, and the profile software do not
get to make that assessment.

Best regards,
John Moody

-----Original Message-----
From: DigitalBlackandWhiteThePrint@yahoogroups.com
[mailto:DigitalBlackandWhiteThePrint@yahoogroups.com]On Behalf Of Carl
Schofield
Sent: Friday, April 07, 2006 8:47 AM
To: DigitalBlackandWhiteThePrint@yahoogroups.com
Subject: Re: [Digital BW] Innova Fibaprint Paper Feed

I corrected that mistake in a follow up post:
"Sorry, put in the wrong numbers for x-rite.  Should be L 96.2 a
-0.52 b 0.56."

So yes they are very different in terms of Lab a and b values
(particularly the latter).  I think the un-filtered (UV) i1 is really
not appropriate to use for assessing color of papers containing OBA.
The Match color profiling software corrects for OBAs but most of us
have been using MeasureTool for aquiring data when making B&W
profiles for QTR and I don't believe MT has the capability to make
the UV adjustment.  I see now why ColorBurst recommends (actually
requires) the UV filtered hardware solution.

Carl


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