[argyllcms] Re: General Questions

  • From: Florian Höch <lists+argyllcms@xxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Mon, 24 Sep 2012 17:21:28 +0200

Am 24.09.2012 08:10, schrieb Michael Nagel:
> (1) dispcalGUI does not report the max and average fit error (or any other
> report) when creating a correction matrix.

True. But you should be able to see it when you bring up the log window
after creating a correction matrix.

> (4) yes, this is a little bit unclear to me, I'm just trying to understand
> the options and possibilities of the ADVANCED GAMUT MAPPING menu (in
> dispcalGUI):
> By default in dispcalGUI, under the Advanced Gamut Mapping Options menu, the
> source profile is set to sRGB.icm. I am not sure if it actually maps to sRGB
> if I do NOT make any selections in any of the options in the Advanced menu
> (Gamut mapping for perceptual, Gamut mapping for saturation, etc.)... ?

You need to tick either of perceptual or saturation (or both) checkboxes
(hmm, perhaps I should gray out the profile selector if not at least one
of the checkboxes is ticked).

> What would I select (or not select) if I want to calibrate my wide gamut
> display to the widest gamut possible (not restrict to sRGB) ?

Selecting a source profile for gamut mapping will not limit the gamut of
the display, it affects the source to destination mapping (i.e. if you
process a lot of sRGB images, it makes sense to choose sRGB as source).
Please note that this sort of gamut mapping will typically improve the
results when mapping from a comparatively large colorspace (e.g.
AdobeRGB) to a smaller destination space (e.g. a display with a gamut
roughly the size of sRGB), and may not be needed if the destination
gamut is large enough to accomodate the gamut of the source colorspace.

> If I do want to map my display to sRGB

I think you may have misinterpreted the options. Choosing a source
colorspace does not map the display to this colorspace, but the other
way around (e.g. to stay in the sRGB example, it affects the conversion
from sRGB images to the display gamut if choosing perceptual intent).

> (or any other color space), what
> would be good, default selections for the options "Gamut mapping for
> perceptual intent", " Gamut mapping for saturation intent" and "Default
> rendering intent for display device profile" ? I am unsure what to select
> here...

In dispcalGUI I've chosen the defaults with a bit of careful
experimenting. In my experience, users seemed to prefer a mapping that
gives a result comparable to relative colorimetric + black point
compensation, which is achieved to some extent by the "Luminance matched
appearance" setting. It is up to you if you also want saturation tables,
but if you won't use the profile with saturation intent (read: if you're
not sure you will, you probably won't), it makes sense to leave it out
to cut down on calculation time when creating the profile.

Florian Höch

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