Re: Monitor calibration & profiling in a multiuser OSXenvironment.
Re: Monitor calibration & profiling in a multiuser OSXenvironment.
- Subject: Re: Monitor calibration & profiling in a multiuser OSXenvironment.
- From: Roger Breton <email@hidden>
- Date: Mon, 01 Sep 2003 22:01:42 -0400
>
Roger Breton wrote:
>
> The way I understand the latest v4 ICC specs and the incorporation of the
>
> chromatic adaptation tag in monitor profiles, practically any color
>
> temperature (above 5000K) can be used for calibrating and profiling monitors
>
> successfully. Because, no matter what the state of the monitor is the
>
>
V4 doesn't add anything significant in this area. The chromatic adaptation
>
tag merely provides a way of defining the _method_ of the chromatic
>
adaptation.
>
The amount of adaptation, is the same as it has always been (ie. the
>
difference
>
between the native device white point and the PCS white point.)
>
>
Graeme Gill.
I knew someone would catch me! I agree that v4 does not add anything new to
the table with regards to chromatic adaptation and the way it was done in
the previous specs. It does, however, mandates the type or chromatic
adaptation used to calculate D50 corresponding colors to be declared in a
new 'chromatic adaptation' tag.
What gets me is that I've never been able to go from the encoded XYZ
colorants matrix, as encoded in a profile, back to the real, physical
monitor phosphors chromaticities, through the chromatic adaptation matrix? I
am able to follow the forward transform, that is from physical, measured
phosphors chromaticities to 'relative' XYZ colorants as encoded in a
profile, but, to date, I have not found a way to calculate the backward
transform, from a given monitor profile to physical chromaticities. A few
months ago, I have asked people on the List to contribute some of their
monitor profile at a time I wanted to compare the gamut of the SONY Artisan
to my lowly Mitsubishi900u. But I gave up at a point that I had to figure
how to go from 'normalized' chromaticities to physical (or absolute)
chromaticities because I was so confused how to calculate the normalized
illuminant tristimulus values from the chromatic adaptation matrix.
Someone contributed some worked out example to calculate that last step but
I have not had the chance to revisit those calculations since the last part
of summer.
You must have all that math figured out in Argyl?
Regards,
Roger Breton | Laval, Canada | email@hidden
http://pages.infinit.net/graxx
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