[argyllcms] Re: Monitor profiles
- From: Graeme Gill <graeme@xxxxxxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Fri, 3 Feb 2017 13:24:59 +1100
Roger Breton wrote:
Hi Roger,
So my question, is there any way to “boost” Argyll’s monitor profile red
content, overall,
short of editing the White Point tag in XYZ, in the profile?
sorry no, it's not designed for manual modification, it's designed to
reflect what has been measured - i.e. accuracy is the goal, not
color creativity.
Any kinds of global corrections? Nothing I could see, so far…
There are ways, but they are not convenient or easy for what you
seem to want to do (i.e. using the refine tool with a manually
tweaked reference.)
So I am still faced with the task of visually matching a SWOP2006_C3 AbsCol
set of proofs using :
a) Argyll 200 patches monitor profile
That's really small if you are after quality. 1000 - 2000 is more
in the range. Matrix vs cLUT and L*a*b* vs. XYZ PCS is worth playing
with too.
b) my lowly NEC PA271W monitor
c) the free NEC Multiprofiler panel control
In Photoshop, I could tell the colors were off, not “red” enough?
What source profile though ?
- and Photoshop may not respect absolute colorimetric intent.
Did you measure the dE of source colors to what the display shows (assuming
the colors are in gamut ?)
So, using Multiprofiler, I interactively adjusted the profile White Point x,y
until I
was visually satisfied with the color match of my 32 test images.
Now, this is where the catch lies.
At that point, the new point was brought down from about 5000K to 4491K –
huge, I
know.
So I turned to my humble VisualBasic “home” software and proceeded to measure
the 200
patches in the *.ti1 file, again, and create a new ICC profile from the new
*.ti3
measurements.
Without a clear understanding of the image workflow (what profiles, what intents
and other tweaks (i.e. BPC)) first, I have my doubts about whether this is a
good direction.
i.e. you need to be crystal clear about what's happening to the numbers, and be
able
to replicate what Photoshop is up to using icclu to be able to actually figure
out
if there is an accuracy or workflow problem, or whether you are dealing with
a limitation of colorimetry (i.e. viewing condition effects) or an observer
variability
effect.
What I do believe is that, I need to edit the White Point inside the 4491K
profile and
then the colors “should” match.
It depends what the source of the mismatch is. If it is purely white point
(due to some viewing conditions issue ?), then dragging all the other colors
along with the white point shift may be enough. But if this is not the
issue, then it probably won't help!
P.S. I don’t dare to say, could Argyll *ever* add a rudimentary white point
editor? Or,
at least, is there a way to edit the white point of an Argyll profile using
any of
argyll’s tools?
No point, since the ICC and software vendors have sabotaged absolute intent in
display ICC profiles. ArgyllCMS tools support display absolute intent, but to
take
advantage of that you probably need to avoid other tools in doing the color
management
and getting the pixels to the display.
So typically you control the display white point using calibration, and so (of
course)
it's easy to dial in your target white point using dispcal.
Cheers,
Graeme.
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