[argyllcms] Re: help with camera profile

  • From: Alberto Ferrante <alberto.ferrante@xxxxxxxxxx>
  • To: "argyllcms@xxxxxxxxxxxxx" <argyllcms@xxxxxxxxxxxxx>
  • Date: Wed, 01 Aug 2012 13:03:25 +0200

Stephen T wrote:
> Alberto, you need an independent, objective test.

Stephen, you are completely right.

> Stop worrying about profiling errors and wasting time evaluating results on 
> screen.

Again, you are completely right. Even though, for the moment being I
found a good compromise that works quite well in different lightning
conditions (including concert photos, that are normally quite challenging).

> Get a ColorChecker 24, photograph that, process as linear 16-bit TIFF 
> (exactly 
> as you did when profiling), evaluate delta-E 2000 for the CC24 with profcheck 
> and your IT8.7 profile.

I was actually planning to get a ColorcheChecker Passport: it has pretty
much the same price and it could be useful to me not only for checking
the profile. If I understood well, the 24-patch "classic" target should
be the same as the standard 24, just smaller... Is that correct?

> This test is independent of your IT8.7/2 target, workflow, RGB colour spaces, 
> display, printing, personal biases, etc. Delta-E 2000 is an objective, 
> quantitative measure of colour difference and reasonably consistent with 
> human 
> perception.

I will perform this test as soon as I can get the target.

A question I was asking myself: cannot the problems with
shadows/highlights be related with the dynamic range of the camera?
Specifically, the dynamic range of the target is roughly 8 stops (gray
patches from full black to full white on paper). Most cameras, in raw,
can register more than 8 stops of dynamic range and, therefore, the
model built in the profile will not cover directly the missing parts (it
may cover them through some kind of interpolation, that may not
correspond to the reality)... Am I wrong?

Thanks again for the great help!


Home page: http://www.alari.ch/people/alberto
Photo galleries : http://albertoferrante.name
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