Client hints: Add support for hinting Display Gamut / Color Profile

Hi, my name is Gunther Brunner and I work for CyberAgent, Ltd.
We are building a real-time image processing service.


I would like to discuss adding client hints support for the following Display related Header Fields:

Viewport-Color-Gamut
https://drafts.csswg.org/mediaqueries-4/#color-gamut <https://drafts.csswg.org/mediaqueries-4/#color-gamut>
Viewport-Color-Profile
https://www.w3.org/TR/css-color-4/#at-ruledef-profile <https://www.w3.org/TR/css-color-4/#at-ruledef-profile>


The reason for this request is that recently, there has been a huge market increase in Displays that are non-sRGB (In particular DCI-P3 and AdobeRGB displays).

As an example: iPhone 7, Galaxy S7, MacBook Pro, Surface Studio, all of them support DCI-P3 wide color.

However since the “color-gamut” it’s a display thing the only way to detect for wide-color support from server side would be Client Hints since its not even possible with UA-sniffing (for most cases).

I know the spec is past WGLC, 
but still would like to discuss this further, and its feasibility.

Thank you.

Regards,
Gunther Brunner