[argyllcms] Re: Black-/White-Level Observer Dependency?

  • From: Juergen Lilien <jp.lilien@xxxxxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Mon, 20 Sep 2010 17:11:09 +0200

Graeme Gill wrote:
> Juergen Lilien wrote:
>> there seems to be a dependency between the chosen Observer in Dispcal
>> and the measured black-/white-level.
>> Is this dependency to be expected?
> Yes. The 1964_10 observer Y curve is a different shape (particularly
> in the shorter wavelengths), and this results in a slightly different
> Y value.

Maybe I'm wrong, I'm still learning in this subject area, but for me
the question remains, if you should use another observer for the
luminance calculation. The SI base unit Candela seems to be tied
to the CIE 1924 photopic V(λ) luminosity function (used in the CIE 1931
standard observer). There are also attempts to improve it, but I have
doubts that you can still name it "cd/m²" if you change the observer.

Regards, Juergen

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