On Aug 10, 2015, at 7:34 AM, Graeme Gill <graeme2@argyllcms.com> wrote:
[I]n practical terms the illuminant standards are conveying the spectral shape, not any particular absolute level - after all, you can change an illuminants intensity simply by the distance you are from it. You are therefore at liberty to normalize them in any way you want to suite your given purpose.
Thanks; I've tentatively come to that conclusion and I'm glad to get confirmation.
This <https://en.wikipedia.org/wiki/Luminosity_function> explains why 555nm is the peak of the Y curve.
...and the choice of 1.0 for the value for the peak would therefore be sorta arbitrary in the same sense that the choice of absolute illuminant level is arbitrary, so long as you get your multiplication (and any subsequent re-normalization) right, I presume? Makes sense. I've been mimicking what I've seen out of caution and it's worked. Knowing I guessed right is nice. Thanks! b&