Re: Monitor calibration and monitor profile
Re: Monitor calibration and monitor profile
- Subject: Re: Monitor calibration and monitor profile
- From: Roger Breton <email@hidden>
- Date: Wed, 11 Jun 2003 10:40:07 -0400
>
>> My working space is mainly ColorMatch.
Good. I myself have started to adopt BetaRGB lately which is also D50 based
but the a 2.2 gamma that I find more natural than 1.8 (but that's me).
>
>> As well, I typically calibrate my
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>> monitor (CRT PressView and Powerbook) to a similar D50 setting (I've since
>
>> started using "native/2.2 for the PB).
Have you had the chance to measure the chromaticities of your calibrated
white point, on both systems, and found them to be close to D50 (x=0.3457
and y=0.3585)? That's the first thing I would do to build confidence in your
calibration.
With iMatch v2, it isn't possible to make this kind of measurements on
screen (as compared with basICColor or OptiCal who provide you withample
numerical feedback) because the software is not designed that way. One 'work
around' I found is to hit the Presets button in the 'Set the White Point'
dialog and force the software to come back with a numerical readout of the
'current' (i.e. measured) color temperature. Otherwise, if you leave it at
the default 'RGB Controls' you can't get that kind of information. What you
get is those red, greeen and blue inverted triangles that, when aligned in
the center, tells you that you've achieved the target color temperature in
hardware.
Others can correct me if I am wrong here (and I'm always willing to learn)
but if you look at the curves inside your video card gamma tag (VCGT), with
a tool like the OSX ColorSync Utility, you can see how much of your target
color you've actually achieved in hardware calibration. If the three curves
are close to one another, on the top right hand side of the graph, that's an
indication that the system did not have much to do in software to reach your
target white point beyond what you achieved in hardware, when you adjusted
the three 'color balance' sliders.
>
>> Viewing an untagged and un-color
>
>> managed image in Photoshop and another viewer that's not color profile
>
>> savvy, the two images look different; the image viewed in PS has a reddish
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>> cast to it. If I assign the image the monitor profile to it, the two views
>
>> match.
You're saying that when you look at an image in Photoshop (v6+?) and that
the image is actually untagged the image looks reddish? If ColorMatch is set
as your RGB Working Space then I'm at odds as to explain what is going on.
You see, if ColorMatch corresponds to your current RGB Working space
(perhaps it is set to AdobeRGB?) whether you have the image tagged (with
ColorMatch) or untagged should yield the same appearance. Provided your
monitor profile is selected in the Monitor Control Panel (or System
Preferences in OSX). You should check to make sure it is. You can also see
if that's the case opposite MonitorRGB in the RGB Working Space drop down
list in Photoshop 6+ Color Settings dialog box.
>
>> Is the difference between the two views with and without the monitor profile
>
>> the difference between calibration and profile, ie...how far off the
>
>> calibration is from it's target? If so, wouldn't calibrating the monitor
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>> (accurately) to the same standard as your working space (setting your white
>
>> point with individual RGB guns) give you the same look of an image whether
>
>> the application was profile savvy or not? Similar in PS 5.x to toggling
>
>> Monitor Compensation on and off.
You need to tell me more.
Roger Breton
Laval, Canada
email@hidden
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