[argyllcms] Re: Camera matrix profile, adding ti3 perfect white data set

  • From: Milan Knížek <knizek.confy@xxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Thu, 25 Feb 2010 08:29:55 +0100

Iliah Borg píše v Pá 22. 01. 2010 v 11:39 -0500:
> Dear Elle,
> 
> > profile check complete, peak err = 33.155823, avg err =
> > 7.494565
> 
> The peak error value you are reporting is untypically high.
> I never got more than 20, average 12, and max of 7 with
> modern high-end cameras.
> 
Iliah - the numbers you refer to is your experience over wide range of
targets or just specific ones?

I have been using two IT8.7/2 by Wolf Faust and never got peak err below
20 (no matter if clut, matrix+gamma, PCS XYZ/Lab or what camera used -
EOS 300D, 30D, 5D MII).

Now with ColorChecker, I get significantly better numbers like you
wrote.

> There might be one or several problems with the workflow:
> 
> - target is unsuitable
Wolf's target is printed on non-glossy Kodak Professional paper and it
still is quite difficult to avoid reflections. With CC matte pigments,
it is much easier.

> - target reference file is not accurate
I do not have spectrophotometer to to check.

> - flare

Not many people share the usual errors with the targets/camera
combination, so especially for a beginner it is difficult to know if the
numbers are "normal" or something is wrong.

Regards,

Milan Knizek
knizek (dot) confy (at) volny (dot) cz
http://www.milan-knizek.net - About linux and photography (Czech
language only)

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