[argyllcms] Re: Display Calibration Hardware Capabilities

  • From: János, Tóth F. <janos666@xxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Sat, 4 Feb 2012 03:15:58 +0100

> It's not that clear cut, particularly using Argyll adaptive.

My understanding is that Adaptive mode only decreases the effect of
random measurement errors by averaging more samples and increases the
accuracy of the of dark measurements only.
But they collected many samples (more than one instruments were used
on more than one display units), so there is averaging there, even if
they didn't use the ArgyllCMS Adaptive mode. And dark accuracy doesn't
really matter with the absolute errors on white patches.


I usually measured about the same white and primary color coordinates
with standard and adaptive modes. The huge difference is in the dark
measurements.
The standard mode is unusable even with cheap LCDs (>0.2 cd/m^2 black
level) if I want to know the color of dark patches too (not only a
very rough estimation about their luminance). But I get very accurate
black luminance readings even in the ~0.02 cd/m^2 ranges in adaptive
mode (my black luminance readings are very very close to what others
get on the same plasma display models with Klein K-10 colorimeters)
and the color gradient readings of the low contrast LCDs also look
good in Adaptive mode (practically useless in standard mode ; but even
the adaptive mode loses the track too soon on high contrast displays
such as plasmas when measuring primary color gradients...)





According to the data publicized in the review (the link in the first
E-mail of this conversation), the mean and peak absolute error of the
CM and i1Pro spectros are significantly (about four times) higher than
what they got with the i1d3 colorimeters on various display types.

This sounds like I probably get about the same or even higher absolute
error if I create my own *.ccss files with my CM spectro.


Of course, they used a limited number of hardware units but it's still
scary enough fro me to keep the CM away from the displays if a custom
ccss file from a CM/i1Pro spectro can actually decrease the accuracy
of an i1d3 colorimeter (moreover this seems very probable).

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