Re: Yellow too high on GRACoL 7
Re: Yellow too high on GRACoL 7
- Subject: Re: Yellow too high on GRACoL 7
- From: Steve Upton <email@hidden>
- Date: Thu, 6 Apr 2006 18:09:12 -0700
At 8:55 PM -0400 4/6/06, Roger Breton wrote:
>Jim,
>
>I listened in on the Gracol webinar this afternoon and was apalled (I think
>that's the right word) by the lack of guidelines relative to optical
>brighteners in the G7. Imagine, all the presenter was able to relate during
>the 1 hour and a half presentation was "a paper with no optical brightners
>is required to implement the G7 methodology". I mean, is that it? The ISO
>Lab coordinates suggested for the #1 "Gracol-compliant" paper, a* = 0 (+-
>0.5) and b* = -2 (+- 1.0); that's not where the bulk of commercial printing
>takes place in the US (and abroad). So, instead of loosely requiring that
>the substrate be as free of OB, why not use some quantitative guidelines to
>describe OB? Everything is presented as so "mathematical" and so
>"scientific" in everything being done around Gracol, that, the fact that no
>scientific or mathematical way of assessing the level of OB present in a
>Gracol-candidate paper grade sounds like, well, inconsistent.
>
I suppose part of the problem here is that there appears to be no standard scientific or mathematical way of assessing OB.
> Why not coordinate efforts
>with other standardization groups to come up with some kind of quantitative
>"tolerance" for OB, like a DeltaE range, really, instead of leaving it up to
>anyone's interpretation?
that's a great idea but if we wait for other groups to come up with a standard OB number then the spec & process will die in limbo...
it seems to me the only sure-fire method of qualifying OB today is to say "no OB". This has its drawbacks but with no other system in place what are we left with?
In regards to delta-E, that method is flawed as well because the delta-E number will be influenced significantly by the UV component in the light of the measurement instrument. nasty!
While we would all like a standard or specification to be nailed down forever I think that they should really be living & breathing beasts that can be improved upon and enhanced as we move forward. In other words, I doubt OB qualification has been ruled out of all further GRACoL work, it just is practical (read unavailable) for today's GRACoL.
Regards,
Steve
________________________________________________________________________
o Steve Upton CHROMiX www.chromix.com
o (hueman) 866.CHROMiX
o email@hidden 206.985.6837
o ColorGear ColorThink ColorValet ColorSmarts ProfileCentral
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