[argyllcms] Re: R: Re: Neutralize Grey Axis
- From: Gerhard Fuernkranz <nospam456@xxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Tue, 11 Jan 2011 02:10:45 +0100
Am 11.01.2011 01:12, schrieb Graeme Gill:
> Given that D50 is a constant assumption in ICC, then I guess this
> effectively
> translates to an assumption of a spectrally flat reflective media ?
> [ie. a media that has a D50 white point when illuminated with D50.]
Hi Graeme,
yes, I agree, this would imply that they basically attempt to emulate
the reproduction on a spectrally flat medium (still with some blue-ish
(or yellow-ish) "highlights" due to the limitation of the paper).
[ Btw, I do remember that I have seen profiles from PM in the past,
which actually did produce a D50 perceptual gray axis (i.e. D50
mid-tones), bending toward the actual paper color at the top. I never
owned PM, so I was indeed wondering about that, but now I guess that
these profiles were made with this particular option. ]
>
> But the reality is that the observer has no in built neutral reference,
> and adapts to the viewing situation, so I'm not clear on the
> circumstances
> in which rendering as if in an absolute colorimetric mode with the source
> being a spectrally flat media, gives a visually desirable looking
> neutral.
>
> If the output media has a cool white point itself (ie. lots of FWA), then
> the neutrals would look too warm. If they don't look too warm, then
> the observer must be adapted to something other than the output media.
> What
> are they assumed to be adapted to ?
Good question, obviously they assume adaptation to the illuminant color.
If the paper dominates the field of view, then I also guess that the
observer rather adapts to the paper color. I'm wondering though, whether
this still applies if I have e.g. a borderless photo print, where the
majority of the pixels of the scene is rendered according to an adapted
white point with D50 chromaticity, while only a few (clipped) highlights
are visible as unprinted paper? I would not rule out that an observer
possibly adapts to the "average white point" of the printed scene (i.e.
to D50) in such a situation?
Regards,
Gerhard
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