ProfileMaker, Leopard, multiple displays, and the LUT (vgct)
ProfileMaker, Leopard, multiple displays, and the LUT (vgct)
- Subject: ProfileMaker, Leopard, multiple displays, and the LUT (vgct)
- From: Martin Diers <email@hidden>
- Date: Mon, 12 Jan 2009 09:39:43 -0600
I discovered some maddening behavior in PM5.0.8 and Leopard.
The setup: MacbookPro 2.33 Core2 w/ aftermarket WUXGA panel.
Samsung 2253LW external display.
OS: 10.5.5
PM 5.0.8 Pro Plus
eye-one Pro
Target: 65K, 2.2.
Here's the deal:
After installing a new LCD panel in my Macbook Pro, I of course
recalibrated it. In the process, I noticed that my 22" Samsung display
had drifted a bit toward orange (warmer and more yellow) over time, so
I went ahead and re-profiled it also.
I experienced some very bizzare behavior.
First problem: With the calibration setting at 100% brightness, there
is a significant drop during the transition from calibrating to
optimizing. I had not remembered seeing this before. Solution: Set
brightness to 95% and it does not happen. Without doing this I could
not get a decent profile on the Samsung.
Second problem: When attempting to compare the displays with one
another, the Samsung was red-shifted. Weird. So, I rebuilt both
profiles from the saved measurement data, just to make sure I didn't
mess up something. I then noticed that both profiles, the external
Samsung 22 and the internal LCD panel, produced identical color on the
LCD panel. WTF?
For whatever reason, ProfileMaker had grabbed the active LUT from my
Macbook LCD, and put it into the Samsung profile. I verified this in
the Colorsync Utility. Curiouser and curiouser.
I then grabbed a profile from a completely different monitor, and
loaded it in to the Macbook LCD. Everything was yucky yellow. I
generated the profile for the Macbook LCD once more, again using the
saved measurement data. This time, the resulting profile ended up with
a copy of the LUT from the sickly yellow profile. Again, I confirmed
this in ColorSync.
Here's the deal: when you generate a display profile in ProfileMaker,
on Leopard (perhaps on all versions), it takes whatever LUT is active
on the screen that the ProfileMaker window is presently on, and loads
that LUT into the resulting profile.
This is pure stupidity. What were they thinking?
Shouldn't the LUT info be stored in the measurement data? Evidently it
is not.
So, I started all over, careful to have only one display active at a
time, setting brightness target to 95%, running through a calibration
and measure, and immediately generating a profile. This worked
perfectly.
From this little exercise, it seems to me that it is utterly
pointless to save measurement data for a display, since the LUT curves
are not saved along with it.
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