[css-color] Canvas may add a half-float, gamma-corrected, Rec. 2020 colorspace

[svgeesus]

https://drafts.csswg.org/css-color/#predefined-to-lab

Canvas proposes adding a 16bit half-float linear rec2020 space

The CSS syntax is already a float, but the issue here is the linear transfer function compared to the rec. 2020 transfer function. This could be addressed with a new keyword, like linear-2020 or something like that, if needed.

[svgeesus]

Turns out it is not linear, but uses a reflected sRGB transfer curve. Also not Rec.2020 any more,but extended sRGB.

See summary and TAG review.

[svgeesus]

Not clear the proposal is still active