Re: [css-color] wider/deeper colors

Hello Dean,

Saturday, February 13, 2016, 4:12:29 AM, you wrote:

> I'm now flip-flopping back to something that uses existing,
> well-known profiles, which wasn't exactly what we originally
> proposed, but I think they make more sense.

I agree.

> Here is the text:

>>>> 1. Add a new media query that is able to detect the "depth" of
>>>> the display. I put that word in quotes because I think the
>>>> current "color" query isn't sufficient

agreed

>>>> and we need a term to
>>>> better describe what we're trying to detect. The "color" query
>>>> examines the number of bits per channel, but that doesn't allow
>>>> you to ask if the display can show things outside sRGB. Instead
>>>> we suggest there should be range-type query that allows you to
>>>> detect "normal" (typical displays from today, in the sRGB range
>>>> or about), "extended" (wider gamut displays, in the DCI P3 range
>>>> or about) and "super-awesome-needs-a-better-name" displays (very
>>>> wide gamut displays, in the Rec. 2020 range or about). I believe
>>>> this might be the first media query that has named values but
>>>> works as a range. We don't have good suggestions for the name of
>>>> this query.

> (#include the color expert equivalent of "I am not a lawyer")

> I suggest the name of the query be "color-support".

How about color-gamut? Because gamut is the usual term for "the range
of colors that can be displayed".

> It implies that
> the software and hardware do their best effort to represent colors of this range.

> I think we might be able to get away with three values.

> color-support: sRGB | P3 | Rec2020

Yes (subject to saying exactly what P3 is meant).

> color-support: sRGB-equivalent | P3-equivalent | Rec2020-equivalent

Those are longer, and the spec text can say the same thing.

> … because there are many different forms of P3 (e.g. Photoshop
> allows you to choose from 8!) and not all displays might be the
> same. For the Apple iMacs, we suggest people use the "Display P3"
> profile when authoring artwork. As far as I can tell, these three
> values would cover the two most well-known and supported important
> steps up from what is common today. And we can add new steps if necessary.

> I guess the main point is that we can't really be specific here,
> because there are lots of choices, and you can find many articles
> that describe how existing Ultra-HDTVs say they support Rec 2020 but
> at best cover 90% of the gamut.

This is also true of wide gamut monitors, they tend to say things like
"95% of AdobeRGB" and stuff like that. (They also tend to hand-wave on
whether that is a 3D volume comparison of a 2D, area comparison on a
chromaticity diagram).

I think this is fine - it is an aim point, not a guarantee of complete
coverage.

>  What we're trying to achieve is a
> way to allow a developer to at least try to provide images that are
> the most accurate for the user's configuration (e.g. they want to
> send a P3 image if possible, but otherwise would be better off
> sending an sRGB image rather than risking clamping).

Exactly.



-- 
Best regards,
 Chris  Lilley
 Technical Director, W3C Interaction Domain

Received on Tuesday, 16 February 2016 09:27:13 UTC