[argyllcms] Re: Image dependent ?
- From: "Yves Gauvreau" <gauvreau-yves@xxxxxxxxxxx>
- To: <argyllcms@xxxxxxxxxxxxx>
- Date: Tue, 13 Nov 2018 10:19:23 -0500
Thanks, I think this settle the matter for me. I'll go spectro soon.
Maybe, I'll ask you guys one last thing about spectrophotometers, with the
budget I have, not much more than $500 US, what about used instrument? Any
other choice then X-Rite? Any other suggestions? Another reason I'm considering
the I1 Studio is that I could sell my I1 Display Pro, unless it's better to
keep them both.
Thanks again,
YG
-----Original Message-----
From: argyllcms-bounce@xxxxxxxxxxxxx [mailto:argyllcms-bounce@xxxxxxxxxxxxx] On ;
Behalf Of Claas Bickeböller
Sent: Tuesday, November 13, 2018 8:47 AM
To: argyllcms@xxxxxxxxxxxxx
Subject: [argyllcms] Re: Image dependent ?
Hi Yves,
Am 13.11.2018 um 14:14 schrieb Yves Gauvreau <gauvreau-yves@xxxxxxxxxxx>:
In the mean time, I wonder, if using a scanner would be an
improvement over using profiles made 5 years ago
hard to say without knowing how well the profiles still describe your output
system.
But in general using RGB sensors (being it a camera or a scanner) as a colour
measurement device is not straight-forward if you expect at least some accuracy.
The reason is that the sensitivity of the RGB sensors differ fundamentally from
the sensitivity of our eyes.
For a „traditional“ scanner profile typical accuracy levels are (values
obtained by a scanner compared to spectral measurements):
Avg dE2000: 2.8
95% dE2000: 5.6
Max dE2000: 15.3
BTW: The same is true for most „cheap“ filter-based display measurement devices
(like your i1Display) but this issue can be overcome with good results by a
built-in correction matrix which is ideally monitor-dependent.
Such a correction is not that easy if you want to use a scanner to „measure“
prints.
Two examples of additional issues:
1) We can see a difference between pure K and a black composed from CMY(K). A
typical scanner sensor does not detect this difference necessarily.
2) Influenced by the surrounding patches a scanner detects different RGB values
for a patch although the colour didn’t change (the reason is flare).
We solved such issues for our IQ-501 (that’s a built-in measurement device for
our toner production printers. It uses a combination of spectral and RGB
sensors) and it is not sth. you get done in a week ;-)
So I would not expect too much if I were you.
Best regards
Claas
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