[argyllcms] Re: Blue Cast to Color Munki Profile

  • From: "Alan Goldhammer" <agoldhammer@xxxxxxxxxxx>
  • To: <argyllcms@xxxxxxxxxxxxx>
  • Date: Thu, 28 Apr 2011 08:02:53 -0400

Thanks for the explanation.  The bluish cast seems to be independent of OBAs
in paper.  I did a quick profile of an OBA-free paper under both D50 and D65
and the bluish cast is still there with the D65 profile when the Simulate
Paper Color box is checked.  It may be as you note below how Photoshop uses
the absolute intent.  There may be a shift in the spectrum as you note in
the final paragraph as well so that the cast affects all the colors.  We
probably never see this in practice because other profiling software
prepares D50 profiles.  The configuration of Argyll to achieve the desired
results and remove artifacts is what is critical to me.

Again thank you for responding.

Alan
-----Original Message-----
From: argyllcms-bounce@xxxxxxxxxxxxx [mailto:argyllcms-bounce@xxxxxxxxxxxxx]
On Behalf Of Graeme Gill
Sent: Wednesday, April 27, 2011 8:49 PM
To: argyllcms@xxxxxxxxxxxxx
Subject: [argyllcms] Re: Blue Cast to Color Munki Profile

Alan Goldhammer wrote:

> made profile in Photoshop and used it as the soft proof, there was a
> noticeable blue cast to the image as though the bluish color from the OBA
> was somehow showing up.  I remade the profile using all the defaults (D50

I guess Photoshop is using absolute intent for its soft proof, hence
this effect.

> instead of D65) and only keeping -cmt&  -dpp respectively.  This profile
had
> no blue cast at all so I think the problem is solved.  What was curious is
> that the blue cast did not show up in the print, only in Photoshop under
> soft proofing.  With the blue cast in a profile, soft proofing to adjust
> colors in Photoshop would be quite difficult.

If you are using any relative colorimetric rendering mode, then device white
is always rendered as device white, so no, you won't see any effect - or
rather
the effect is more subtle than that. Specifying D65 as the viewing
illuminant
will change the profile, since (depending on the spectral characteristics
of the inks) it will change the color of the patches. But the default
D50 and D65 have very similar spectral shapes, so the normal white point
adaptation will pretty much cancel any effect out using a relative intent.
The absolute white point difference will remain though.


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