[argyllcms] Re: Neutralize Grey Axis
- From: Graeme Gill <graeme@xxxxxxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Thu, 13 Jan 2011 11:21:52 +1100
Ernst Dinkla wrote:
the neutral/white reference. In a monochrome image it could be the
global impression or an average of the lighter tones.
Sounds reasonable that with a monochrome image that there's a lot
of image that is setting the observers chromatic adaptation.
There has been a somewhat heated discussion on the use of the term
"metamerism" for what actually should be called color (in)constancy with
changing lighting etc. Colorsync list half a year ago.
Yes :-) I prefer the term "metameric failure", since "Color Constancy"
is overloaded.
media base as a neutral reference. So it is possible that someone
describes the paper correctly as blue or the Dmax black as warm in a B&W
image without another print or white reference next to the one described.
Sounds reasonable, and a possibility if the neutral ramp is composed
of multiple colorants and the lighting is not what is being assumed
by the color management system. I didn't get the impression that
this was what was going on in the situation being discussed though.
What I mentioned in the other message that profiling / media presets
(LUTs) can not compensate a warm black ink in some cases is related to
what I describe above. Papers with enough FBA content like the example b
-11 mentioned in the thread will one way or another show too much hue
deviation along the B&W tone range if the black ink is too warm. In the
end you will at best get a kind of gradual split toning over the tonal
range with lighting including UV. It will also be very sensitive to
changing illumination.
FWA/OBE's can certainly play havoc with attempts at color management,
and papers with high levels of FWA should therefore be avoided if
good color results are desired.
Graeme Gill.
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