[argyllcms] Re: Dell U2711 - is it any good?

  • From: Knut Inge <knutinh@xxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Wed, 22 Jun 2011 16:40:34 +0200

What is the problem that (monitor) calibration tries to solve? I would
guess "the fact that the precise perseptual response for a given
display input is unknown, and for some applications, e.g. image
editing, there is a need to know what the user is seeing". The reason
why it is unknown is because display manufacturers generally do not
share the ideal/new response of their products in a machine-readable
format, and because 2 identical, new displays may have somewhat
different response, a third identical display may have another
response after years of (ab)use, and a "cold" display may differ from
a "warmed up" display.

If we had an instrument that correlated perfectly with human visual
system, it would be easy. Connect it, calculate the error, and feed
back some correction. Such instruments do not exist.

I am a bit lost when you say that a single monitor+colorimeter
correction matrix can be used to correct future measurements. How can
one know that the "unknown stuff" that makes monitors/colorimeters
change over time and over production runs, does not also make this
correction invalid? Are there known knowns and known unknowns?:-) May
one assume that the spectral response of each primary is constant (and
can be baked into a correction matrix), while the flat gain of each
primary is fluctuating and should be calibrated every once and again
using a colorimeter and correction matrix?

Thank you for your time enlightening me

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