[csswg-drafts] [css-color] D50 mismatch in Lab ↔ sRGB algorithms

danburzo has just created a new issue for https://github.com/w3c/csswg-drafts:

== [css-color] D50 mismatch in Lab ↔ sRGB algorithms ==
In Section [17. Sample code for color conversions](https://drafts.csswg.org/css-color/#color-conversion-code) of the CSS Color Module Level 4 spec, there's a discrepancy with the D50 values being used.

In the XYZ ↔ Lab conversion code, it's assumed to be [0.9642, 1.0000, 0.8249] (as specified by the ICC spec).

However, the D50 ↔ D65 chromatic adaptation uses Bradford matrices from [this page](http://www.brucelindbloom.com/index.html?Eqn_ChromAdapt.html), which have been computed for D50 being `[0.96422, 1.00000, 0.82521]`. 

I think the correct approach is to use the ICC-defined D50 throughout, no?

(Also, I'm not clear on why the ICC value for the D50 white point differs from the generally accepted one. [e.g. Matlab](https://www.mathworks.com/help/images/ref/whitepoint.html)).




Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/2492 using your GitHub account

Received on Monday, 2 April 2018 11:19:43 UTC