Re: UV filter or software correction or wp editing
Re: UV filter or software correction or wp editing
- Subject: Re: UV filter or software correction or wp editing
- From: Roger Breton <email@hidden>
- Date: Tue, 25 Apr 2006 23:13:58 -0400
Roberto,
Do you really have to work with such OB-heavy proofing paper? Why can't you
switch to something less fluorescent, like ProofLine's excellent PressWhite
160 inkjet proofing paper? In my recent testing, I found PressWhite very
neutral. My iCcolor sees it as 96, -0.19, -1.51. That would surely help. I
personally never measure with the UV filter on a DTP70 or any other
instrument. But that's me. I find UV-filtration does more harm than
measuring with UV-included.
> 2) try to 'fill in' the missing spectral values for ProfileMaker to
> accept the data as spectral, and use the brightener correction in
> software.
Are you having difficulty getting spectral data out of the DTP70 in
ProfileMakerPro?
> 3) using Gretag's Profile Editor, select my Gracol Profile and my
> Proof Profile (made without UV filtering or correction), select abscol
> mode and the output Lab->device table, and then go to 'edit workflow
> white point' which will allow me to tweak down the yellow that gets
> added to the background.
That could help. I don't suppose you have access to a GMG ColorProof RIP and
could use iterative proof correction to improve the match between your
Gracol source data and the measured proof data? Do you still have access to
PrintOpen? May be worth trying their Iterative Proofing Correction
procedure. It does not always work but it's a big help most of the time, I
find. May not do much for you, visually, on this dazzling, fluorescent paper
but it would be worth a try.
> Which is supposed to yield more realistic (iow: accurate in terms of
> human perception) results?
Tony Johnson always advocated measuring with fluorescence excitation
included. I don't want to start another debate on FWA, here, but what does
your output looks like?
> I'm concerned that (1) may also be cutting out some ink fluorescence,
A valid concern. But it is not exacly simple to isolate the fluorescence
attributable to the ink from that which is stemming from the paper. Just
quantify the overall level of fluorescence in measurement is mind boggling
to me.
> which should not be cut out since human vision does not adapt to it
Ah! This is news to me, Roberto. I never knew that our color vision was
"insensitive" to ink fluorescence. Do you have anything to back that off?
> (it does consider it, as opposed to white cast to which one adapts).
OK.
> I'm not sure what does (3) does, if it's just a bad hack to do so.
Are you able to compare the effect of this hack with an actual Gracol sheet?
Instead of relying on the numbers?
> And (2), well, filling in missing spectral values just doesn't sound
> so right, does it?
Might help. But do you know which values to add, exactly?
> -- Roberto Michelena
Regards,
Roger Breton | Laval, Canada | email@hidden
http://pages.infinit.net/graxx
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