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.