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

  • From: Graeme Gill <graeme@xxxxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Tue, 21 Sep 2010 11:45:04 +1000

Juergen Lilien wrote:
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(?) 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.

Technically you are right, but I'm not about to complicate things
(and possibly break dispcal) by attempting to have 4 different
values for each reading (selected observer XYZ + 1931_2 Y).

Thanks for pointing this out - I'll add a note to this effect in
the documentation.

If you want an official cd/m^2, then it's simple enough to use the
default observer.

Graeme Gill.

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