[argyllcms] ArgyllCMS V2.0.0 (Profile generation with perceptual intent with compensation for paper white)
- From: Graeme Gill <graeme@xxxxxxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Sat, 18 Nov 2017 19:19:53 +1100
A feature I've (somewhat reluctantly) added in V2.0.0, is a "pm" viewing
condition,
for "Print evaluation with partial Mid-tone adaptation". It can be used with
perceptual gamut mapping for the destination viewing condition (-d), to do full
adaptation to the paper white with partial adaptation in the mid-tones.
The degree of this effect can be changed using the m:N.N override, where N.N
is a number between 0.0 (no mid-tone partial adaptation, i.e. full adaptation
to the paper white, just like "pe") to 1.0 (a high level of partial adaptation,
i.e. mid-tones are chromatically adapted to D50). Note that you can add the m:
parameter to other viewing conditions as an override if you wish.
This may be of assistance when faced with FWA/OBE rich paper in a viewing
environment with strong spectrally flat visual cues.
I really doubt this should be used very often though.
Henrik Olsen wrote:
If evaluating the print right where it’s supposed to hang, it can’t be more
realistic than that. I don’t prefer the bluish rendition of colors edited to
a different tone. Itdoesn’t appear as intended. But does if printed on
neutral paper.
But unless you a covering a tremendous amount of wall space, where the cost
of the paper is significant, why not use FWA free paper and avoid the whole
problem ?
Production wrote:
Viewers are able to perceive that the paper *is* blue and that the blacks are
also too
blue — because none of the other objects around them are boosted with optical
brighteners.
Which seems to indicate that it's an inappropriate environment for using FWA/OBE
rich papers. I think that the partial adaptation is a hint that the judgement of
neutrality is going to be quite variable - highly dependent on the viewers state
of mind and state of visual white point adaptation.
Compromises are being made to keep customers happy and we need to be able to
produce
images that meet certain technical criteria but also mimic those compromises.
I have a strong suspicion that this is a symptom of the pre-press industry
not fully having come to terms with FWA/OBE containing papers. There's more
to it than regulating the level of U.V. in the evaluation environment !
Having the physical evaluation environment full of spectrally flat references
surfaces (i.e. "20% grey paint"), or the soft proof equivalent of a D50 white
point monitor with a 20% grey background displaying an FWA/OBE proof having
a white point closer to D60 on it, is simply setting the viewer up for this
type of partial adaptation problem. I don't think it corresponds to the end
user situation very well at all, where there will not be such strong cross
adaptation cues.
(And I say this having spent the entire of my color management career of 25
years+
dealing with FWA/OBE rich paper stock. You see a lot of it when dealing with
office Color Copier output!)
I seriously wonder if a different viewing environment is needed for evaluating
FWA/OBE rich media, either one without any spectrally flat backgound (i.e.
black ?),
or one in which the media itself can used as a viewing background (perhaps 20%
transparent
black screens that can cover pieces of the same media, resulting in a 20% grey
with
consistent white point ?)
Cheers,
Graeme Gill.
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