[argyllcms] Re: "Wrong" ambient light reading with colormunki
- From: Graeme Gill <graeme@xxxxxxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Tue, 11 May 2010 11:56:05 +1000
Marco Presi wrote:
I found that the ambient light measurement is constantly "lower" if made
with argyll. I have been very careful in keeping the same conditions while
during the measurements: as an example, when the x-rite software returns
80 lux, argyll returns approx. 50 lux. Doing the same measurement on a
debian gnu/linux box gives exactly the same result (please note that the
x-rite software is not available on linux). I tried the same measurements
That's not what I see using V1.1.1. (Note that some earlier releases of
Argyll had some problems with emissive & ambient calibration.)
As far as I can tell, Ambient readings for the Munki are consistent with that
from the manufacturers driver, as well as many other instruments (i1pro,
a Luxmeter etc). Of course none of them agree exactly, but they are consistent
within something like +/- 10%.
So I have no idea why you see such a discrepancy. I am unable to
reproduce the problem.
In addition, when completing the calibration with argyll (I tried to read
the docs carefully), the black point looks too bright: I tried to
compensate it by using all the options I found (-B, -f,), but nothing
changes. I am attaching here the output of dispcal: at the beginning, it
declares that the target black level is the "native", but it then set the
target black to 0.9. However, as can be seen from the "dispcal -yl -R"
output, the monitor is able to reach black levels as low as 0.09 cd/m^2
If you look at the output it says:
"Target Near Black = 0.90, Current = 1.07, error = 0.2%".
Notice the word "Near" ? That's the difference between zero and
the 1% target.
cheers,
Graeme Gill.
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