Re: GRACoL densities
Re: GRACoL densities
- Subject: Re: GRACoL densities
- From: Terry Wyse <email@hidden>
- Date: Wed, 29 Jun 2005 11:36:07 -0500
On Jun 29, 2005, at 8:34 AM, Jon Crook wrote:
Can anyone share with me the standard GRACoL densities. Also, would
anyone
happen to have any GRACol dotgain information to help me build a curve
for
our imagesetter or maybe an ICC profile for our Epson 9600.
GRACoL densities/midtone dot gain (more properly called TVI or Tone
Value Increase) for a #1/2 gloss sheet printed @ 175 lines/inch are:
Solid Ink Density Gain/TVI@50%
C= 1.40 20%
M= 1.50 20%
Y= 1.05 18%
K= 1.70 22%
Note that these are not really "standard" or etched in (litho)stone
yet. GRACoL TR004 (or DTR004) is still very much a work in progress at
this point, particularly in terms of tone reproduction characteristics.
My guess is that when the TR004 is finalized that the TVI values will
be a bit lower (possibly 17-18% instead of 20%) which would also
increase the Print Contrast values a bit. But I'm just speculating at
this point.
If you're using this data to build an imagesetter curve, be careful. I
would strongly recommend that you leave the imagesetter "linear"
(50%=50%) and run a press test to evaluate your current state of dot
gain on press. A linear filmsetter going to press should print within
2% or so of the GRACoL/SWOP dot gain numbers (GRACoL/SWOP TVI is
identical, only the solid ink densities are different). If not, your
press may need "fingerprinting" or a mechanical/consumbles assessment
to find out where the extra or perhaps reduced dot gain is coming from.
On the other hand, if you're using a platesetter, quite typically a
4-7% bump curve is required to bring the on-press gain up to
GRACoL/SWOP specs.
As for your Epson 9600, armed with this information is not nearly
enough data from which to build an ICC profile. You'd need actual
measurement data taken from one of the GRACoL certified press runs. You
can purchase their "generic" measurement data or purchase a set of
press sheets/kits from which you can extract your own measurement data
using your spectro of choice (as long as it's a GMB Spectroscan that
is!).
Good luck,
Terry
_____________________________
WyseConsul
Color Management Consulting
email@hidden
704.843.0858
http://www.colormanagementgroup.com
http://www.wyseconsul.com (coming soon)
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