Re: Repetitive Calibration with Optical
Re: Repetitive Calibration with Optical
- Subject: Re: Repetitive Calibration with Optical
- From: "Bertho Boman" <email@hidden>
- Date: Wed, 22 Jan 2003 19:54:25 -0500
- Organization: Vinland
Thanks Dana for helping out.
The description you give of what is supposed to happen is not what I see
on my system: Win-XP, Matrox Parhelia and PhotoShop-7. I do not know
if this is just my system but others have had similar problems from what
I understand from the posts.
Setting both PreCal and OptiCal to the same temperature really results
in bad result. The gun readings in PreCal changes 10-15% when the
"Calibrate" is toggled in OptiCal and there is also a large change in
screen appearance. David Tobie helped out by explaining that OptiCal
should be set to "Native" to avoid that problem.
In native mode there is still a slight interaction (1%) by toggling
"calibrate" on and off.
What appears to work is to start OptiCal, set color temp to Native and
"calibrate" to OFF and then click on "file/PreCal". In PreCal, I set
the desired color temp and then adjust the guns for balance and desired
intensity.
By following that sequence, I get repeatable results.
Bertho Boman
----- Original Message -----
From: "Dana Gregory" <email@hidden>
>
This reply is in two messages. This is #2 of 2.
>
>
It does not matter whether the 'calibration enabled' checkbox is
marked or
>
not when performing a calibration. OptiCAL will first remove any
existing
>
calibration from the video card LUT so that it can measure the
un-calibrated
>
state of the monitor. After OptiCAL calculates the calibration and
downloads
>
the correction curve to the video card LUT it will then mark the
>
'calibration enabled' checkbox regardless of its condition prior to
running
>
the calibration process.
>
---------------------------------------
>
No, this is not about 'double-defining' the Whitepoint. This is about
PreCAL
>
knowing nothing about the settings in OptiCAL. You want to calibrate
your
>
monitor to D65. You have to tell both PreCAL and OptiCAL. So you
launch
>
PreCAL, tell it you want to calibrate to D65 and then proceed to
adjust the
>
RGB Gain controls of the un-calibrated monitor so that when you are
done the
>
un-calibrated monitor has a Color Temperature of D65! You've actually
>
calibrated the Color Temperature in the hardware itself.
>
>
If you then tell OptiCAL to also calibrate to D65 OptiCAL will
calculate the
>
difference between the D65 Target Color Temperature you have requested
and
>
what it measures the un-calibrated monitor to currently be. Of course
the
>
monitor is already D65 because you just calibrated it in PreCAL. So
OptiCAL
>
will calculate that no Color Temperature correction is needed in the
LUT.
>
You can tell OptiCAL to not even bother to think about adjusting the
Color
>
Temperature by setting 'Native' as the Target Whitepoint because you
know
>
that the Native Whitepoint of the monitor is already D65.
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