[argyllcms] Re: White Point

  • From: Ben Goren <ben@xxxxxxxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Sun, 20 Sep 2015 19:11:42 -0700

On Sep 20, 2015, at 5:15 PM, Hening Bettermann <hein@xxxxxxxxxxxxx> wrote:

I have earlier used -am, but -aX gives better Delta-E values.

A close fit for a small number of samples generally doesn't mean all that much.
Indeed...unless you've got a *lot* of samples and an impeccable workflow for
generating them, you're almost always better off with a looser fit. Especially
over the part of the gamut that you can sample with reflective charts, cameras
are remarkably linear and well-behaved. Unless you really know what you're
doing anything other than -am -qm is going to give worse results, because
you're making the profile tightly fit the errors in your workflow.

-ax -qh has its place...but I don't think I'd recommend it for anything smaller
than a few hundred spectrally diverse patches. I use it...for
synthetically-generated charts of tens of thousands of patches completely
covering the entire theoretically-possible set of reflective spectra. That's
where -ax -qh really shines.

But if you're making a profile from a commercially-available reflective chart,
-as -qm is your best bet.

b&

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