Re: Media Testing for maclife.de
Re: Media Testing for maclife.de
- Subject: Re: Media Testing for maclife.de
- From: Uli Zappe <email@hidden>
- Date: Sun, 14 Sep 2008 17:14:06 +0200
Am 14.09.2008 um 16:41 schrieb Eric Chan:
... improve on existing such generic camera profiles as long as
those were built with the goal of delivering
metrologically exact results.
Uli, I missed the very beginnings of this (long) thread but I'm sure
you defined your "metrological exact" criterion somewhere. Can you
please explain this again? I am particularly interested in if you
are measuring scene-referred or output-referred color, and if you're
using a standard CIE metric (e.g., Delta E 1994). Thanks.
I'm a bit at odds with the scene-referred/output-referred distinction
for theoretical reasons and prefer to think in process chains. For my
evaluation, I'm taking the "earliest" result a user can get hold of in
a specific process chain. For instance, evaluating Lightroom with some
Adobe default camera profile, this would be the image exported in the
default working space (Adobe 1998). For Capture One PRO with some
Phase One ICC camera default profile, it would be the image exported
in this camera specific color space. I'm sure you'd label the first
case "output-referred", but I'm not sure about the second case.
Anyway, I use images of a Digital ColorChecker SG chart shot under
seven different lighting conditions from bright sunlight to
fluorescent and halogen light, and calculate mean/max delta E (1976)
for each of them, then average the result for all 7 lighting conditions.
The mininum delta E would be most "metrologically exact".
I hope to describe this in detail in the upcoming review that Chris
insists I should not make available to the list, and that now
unfortunately will take a couple of more weeks. It's probably best a
detailed discussion waits until then, because otherwise I'll have to
formulate many things twice (and will have almost no time to reply the
next few weeks, anyway).
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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