[argyllcms] Re: Profile generation with perceptual intent with compensation for paper white
- From: Production <production@xxxxxxxxxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Thu, 21 Sep 2017 22:03:03 +0100
On 21 Sep 2017, at 15:38, Graeme Gill <graeme@xxxxxxxxxxxxx> wrote:
But the usual situation with any viewer looking at a print is that
they are assumed to be, and in practice are very largely white point
adapted to the paper white. So no ink = white.
Only if you contrive some sort of viewing situation in which the
observer is not so adapted (partial or mixed adaptation), might
paper not look white. This is unlikely to correspond to how
an observer will see a print.
Graeme
This isn’t true — as I’ve recently pointed out on the colorsync-users list.
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.
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.
The ECI have produced a CMYK profile for FOGRA52 which has blacks that are +3 b
different to Argyll. We need to match those blacks.
Vendors of colour management solutions for the pressroom (like GMG) are adding
large amounts of yellow throughout the entire separation for both FOGRA52 (and
51 also). We need to match those neutrals.
I can appreciate that a mathematical model says differently, but *visually* we
really do need some sliders or aim points that allow us to print images on OBA
paper that don’t look like weak, blue photocopies.
Once upon a time, ProfileMaker allowed you to neutralise the grey axis of
*any* CMYK profile. i1Profiler doesn’t allow this and is now incapable of
producing a usable profile for FOGRA52.
We have the same issue with Argyll. We can’t create an RGB to CMYK conversion
profile for PSO Uncoated v3 that results in images that look similar to a
Photoshop conversion using the ECI profile.
The blacks are far too blue.
Regards
--
Martin Orpen
Idea Digital Imaging Ltd
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