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

  • From: Sam Berry <samkberry@xxxxxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Mon, 27 Sep 2010 15:45:11 +0100

On 27 September 2010 14:18, Graeme Gill <graeme@xxxxxxxxxxxxx> wrote:

> Sam Berry wrote:
>> I would also add that the calculation of daylight and blackbody points can
>> usually be considered outside the closed system, and so trusting any
>> calibration utility to set D65 using the 10 degree observer is likely to
>> give meaningless results (ColorNavigator excepted perhaps). The observers
>> only match numerically at x=y=1/3. D65 is only x,y=0.3127,0.3290 using the
>> 2
>> degree observer. Using any other observer the numbers are just a random
>> shade of white-ish. A new set of BB and daylight curves would need to be
>> calculated.
> Good point. I will fix dispcal and spotread so that the color temperature
> correctly takes into account a non-standard observer (I overlooked this
> in adding an alternate observer).
> I can't immediately think of any easy way to do it. I've had to calculate
D65 XYZ from scratch using the D65 spectrum. To generalise it would seem to
be an awful lot of work. Perhaps a warning that CCTs and VCTs are no longer
valid would suffice?

Graeme Gill.
Sam Berry

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