[argyllcms] Re: R: Re: Neutralize Grey Axis
- From: Graeme Gill <graeme@xxxxxxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Tue, 11 Jan 2011 11:12:50 +1100
"Gerhard Fürnkranz" wrote:
Graeme, I guess it is rather not like absolute colorimetric in the traditional
sense,
but more like "ICC absolute", i.e. a perceptual transformation which basically
maps the
PCS gray axis [0,0,0]...[100,0,0] to a gray axis with illuminant chromaticity
(not
paper chromaticity), while scaling down the luminance (from 100 to paper white)
and
possibly bending the gray axis towards paper white at the top in order to avoid
the
otherwise inevitable clipping.
Hi Gerhard,
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.]
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 ?
cheers,
Graeme.
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