Re: CRT Colorimetry woes
Re: CRT Colorimetry woes
- Subject: Re: CRT Colorimetry woes
- From: "Bruce J. Lindbloom" <email@hidden>
- Date: Fri, 30 May 2003 15:54:20 -0500
Below I have supplemented Roger Breton's table with chromaticity coordinates
(x,y) and correlated color temperatures (CCT). Although Roger's concern has
to do with differences in absolute measurements, I am also puzzled about the
differences in relative measurements. If it was simply a matter of a scale
factor, then all measurements would have the same chromaticity coordinates
and the same CCT.
------------ DTP92 ------------ ---------- i1 ---------
ColorShop OptiCal MeasureTool MeasureTool MeasureTool
2.6.2 3.7.5 4.1.5 4.1.5 Spectral
Classic OSX OSX OSX Mode
== ========= ======= =========== ========= =========
X 94.00 77.79 75.7 70.0 79.5
Y 97.92 80.91 81.5 74.1 83.6
Z 83.92 68.78 57.0 61.6 68.7
x 0.3408 0.3420 0.3534 0.3403 0.3430
y 0.3550 0.3557 0.3805 0.3602 0.3607
CCT 5175 5131 4817 5205 5107
Why is there such a wide spread among measurements taken over a (presumably)
short period of time with the same instrument and monitor? Why does the same
software (MeasureTool) produce different measurements with different
instruments, or even with the same instrument? I don't get it. It shows that
aside from inter-instrument differences, there are significant differences
in the way the each application does the color math. Another possibility is
that the same instrument will not produce the same measurement twice in a
row. It tells me that perhaps one cannot put too much faith in these monitor
calibration/measurement systems (e.g. CCT +/- 200K, x,y +/- 0.01).
--
Bruce J. Lindbloom
email@hidden
http://www.brucelindbloom.com
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