Re: EIZO ColorNavigator and G7 validation
Re: EIZO ColorNavigator and G7 validation
- Subject: Re: EIZO ColorNavigator and G7 validation
- From: Lee Badham <email@hidden>
- Date: Wed, 11 Feb 2009 09:59:58 +0000
On 10 Feb 2009, at 19:06, Todd Shirley wrote:
Just a further note on verifying monitors to GRACoL2006...
In my shop we have about 15 Eizo CG10s and 5 CG11s. I've just tried
the ColorNavigator GRACoL2006 verification routine on 2 of each
model, with nearly identical results. If I calibrate and profile the
monitor to D50, L*, 140 cd/m2, I get a max dE76 of around 15 and and
avg. of around 5. This happened on all 4 monitors, so I guess that
is just the gamut of these devices. The worst patch is either 100C
or the 100c, 100y overprint, both right around 15. If I switch to
dE2000, indeed the max is right around 6.7-6.9 with an avg. of 3, so
I guess these monitors do "certify" if the tolerance is dE2000<7.
When I was checking out what tolerances to use I saw the GraCol
tolerance for the primary was 7 ∆E2000 and though that was too high
for colour critical work. The point of using ∆E2000 is that it scales
very well for different colours and luminances. ∆E76 is really bad at
this kind of comparison because of the really high numbers you get for
yellow/cyan. A ∆E2000 of 2 can equate to a ∆E76 of 13, so we would
have to set the tolerances at something like 15 ∆E76 to get a pass.
This might make sense for yellow, but it won't work for black or
magenta. It''s already complicated enough using ∆E and ∆H and
different tolerances for different colours would be a nightmare to
explain to customers.
These are the default tolerances in viewSIGN:
Average ∆E2000 3
Maximum ∆E2000 5
Paper Colour ∆E2000 3
Grey Balance ∆E2000 3
CMYK Primaries ∆E2000 3
As it's hard to achieve these numbers we've used a scoring system
(like that is used on press in pressSIGN) to give a rating.
If I change the white point to D65 (or 5500), that de76 max goes up
to around 20, so clearly D50 matters. Unlike Dan Reid, I found that
switching the measurement device's compensation table to "none" in
the ColorNavigator preferences had no effect on these numbers. I
also tried switching between my DTP94 and eye1, and that didn't
change the numbers either.
The bluer the light, the worse the cyan will measure because of the
Lab values being measured relative to the white-point, but the white-
point has been artificially changed (using curves either in the
monitor or the profile) making it harder for an RGB monitor to
generate a bluer cyan relative to a bluer light.
Lee
When I visually compare the gamuts in Colorthink, there is of course
a huge cyan/green wedge of GRACoL sticking out of the monitor gamut.
Does anyone find this disparity to be problematic in your workflow?
Do wide-gamut monitors really help people get better & faster
results in color matching? Has anyone tried to use soft-proofing and
then been "surprised" at how the cyans and greens hard-proofed or
printed?
Just curios!
-Todd Shirley
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