[argyllcms] Re: Image dependent ?
- From: Claas Bickeböller <lists@xxxxxxxxxxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Tue, 13 Nov 2018 14:47:13 +0100
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
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“
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.
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