Help required: Getting primary illuminants and white point from ICC file

[Richard Hughes]

2009/12/2 Graeme Gill <graeme2 at argyllcms.com>:
> Actually if you're wanting to plot Yxy values then it's appropriate,
> but I'll note that it's also very misleading in indicating gamut,
> since an xy diagram is highly visually non-uniform. A u' v' plot
> is a better choice to illustrate gamut, while still being linearly
> additive.

Sure, converting the code to plot u' v' should be pretty easy. The
graph is really just for a passing glance, not for any serious
comparison.

> This is due to a disagreement about the interpretation and intent
> of the ICC specification in this regard. Some display profiles
> have a white point tag of D50 even though this is not the white
> point of the display, and encode the absolute<->relative
> transformation in the ChromaticAdapation tag, meaning that
> the absolute white point and colorant values are not obtained
> using a normal absolute colorimetric lookup on these profiles.

This is exactly the information I needed, thanks very much for such a
comprehensive answer.

Richard.