Re: Ooops - D65 != D65 ???
Re: Ooops - D65 != D65 ???
- Subject: Re: Ooops - D65 != D65 ???
- From: Uli Zappe <email@hidden>
- Date: Mon, 18 Jun 2007 22:34:02 +0200
Am 18.06.2007 um 21:01 schrieb Andrew Rodney:
On 6/15/07 7:37 PM, "Uli Zappe" wrote:
Now, I'm aware that (speaking in terms of an xyY chromaticity
chart) there's many different possible (x,y) combinations to
produce a 6500 K whitepoint, but somehow I would have thought that
a D65 whitepoint is an unambiguous standard that defines one of
the possible combinations as a standard.
That would be nice (and useful) but I too haven't seen this to be
the case. Its been many years since I did such a comparison
however. It would be interesting to see if you can measure the
native white point by all devices
and software products (that is an option in some packages).
Not sure what exactly you mean by "measure": I haven't found a
package yet that would tell me the native whitepoint of my display
explicitly in numbers, but most (if not all) of the packages allow to
specify a "native whitepoint" instead of a Kelvin setting, or use it
implicitly in their "automatic"/"beginner" variant.
But even that hardly helps: tell two different calibration devices to
use the native whitepoint, and they'll produce *different*
whitepoints! The only exception here are the Eye-One Display and the
Eye-One Pro, which indeed produce the same whitepoint if (and only
if) the "native whitepoint" setting is used. (If you specify a
whitepoint explicitly, e.g. D65, even these two devices, which use
the *same* software, produce very different whitepoints ...)
But it gets weirder still: today, I got a ColorVision SpyderPro
which, just like the Eye-One Pro, allows to set the whitepoint in xy
coordinates. So I produced profiles with both devices using x=0.311
y=0.344 (which equals 6503 Kelvin). All other settings were as
identical as possible. You can't get any more precise than that, and
still, the whitepoints differ a lot. This is absurd!
I always set LCD's for Native anyway.
The native whitepoint of my Apple Cinema Display 30" is too green for
my taste.
Ironically, by far the best = most neutral looking D65 whitepoint was
produced by the cheapest of all devices, the Pantone/X-Rite huey Pro.
(Must be because it's the only device that comes with software
written in Cocoa ;-)) )
The definition of a D50 white point is pretty darn non ambiguous,
I'd agree. What each package is actually able to produce is or
course quite a different story here.
It really is. You would think that at least high-end packages or
packages of the same manufacturer would show some consistency ...
One additional remark: I was amazed that even in the expensive Eye-
One Pro package, the software is nothing more than a black box
that somehow produces a profile. There's no way to access the and
work with the physical measurement data at all. Is this generally
the casewith this kind of products
Make sure you choose the Advance options in the wizard (at the
beginning).
Of course I did, but I'm talking about a different level of data
access. Even Apple's ColorSync Utility comes closer to what I mean in
that regard, but there you can only look at the profile data, not
edit them.
I also must say (after the first glimpse) that the SpyderPro software
seems to be much better in that regard than even Eye-One's high-end
offerings, which have a professional price point and a "software for
dummies" kind of GUI (even in advanced mode). Hey, ColorVision even
provides a 92 page PDF manual, whereas Eye-One only offers flashy
Flash videos as "documentation" that won't run on a Mac Pro ...
At least part of the mess seems to be that different manufacturers
use the ICC specifications differently (which won't explain the
differences between products of one manufacturer, of course). For
instance, ColorVision obviously writes whitepoint information into
the "wtpt" tag (which seems logical to me); for all X-Rite products,
however, "wtpt" is *always* 0,9642-1,0000-0,8249 on my Mac (maybe the
native whitepoint???), whereas the actual whitepoint settings are
stored with the "lumi" tag, something that the ICC specification
explicitly says should be avoided (ICC.1:2004-10 (Profile version
4.2.0.0), page 32). Again, it's the "market leader" that looks bad
here ...
Unfortunately, I understand too little about ICC profiles to be able
to analyze all the differences with ColorSync Utility only, which is
why I'm looking for software that provides thorough analytical access
to profiles.
Bye
Uli
________________________________________________________
Uli Zappe, Solmsstraße 5, D-65189 Wiesbaden, Germany
http://www.ritual.org
Fon: +49-700-ULIZAPPE
Fax: +49-700-ZAPPEFAX
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