- From: Chris Lilley via GitHub <sysbot+gh@w3.org>
- Date: Mon, 08 Mar 2021 20:13:50 +0000
- To: public-css-archive@w3.org
I'm aware of this requirement, Canvas for example wants to have this as they reference Color 4 for predefined colorspaces.
SVG also needed a stable reference for linear-light sRGB because this is what SVG Filters use by default (and the rest of SVG can also optionally use this). Which is why [`linear-light sRGB`](https://drafts.csswg.org/css-color-4/#linear-light-sRGB) is in the list of defined and exported terms.
What wasn't clear to me though was whether to
1. Expose this to CSS syntax, so you could use something like `color(srgb-linear 0.2 0.5 0.9)`, or
2. Expose the defined terms for other specifications to link to, but not make them available from CS syntax
In terms of extended vs. not, I think that is a separate issue and I am in process of changing all the transfer functions (EOTFs) to cover the full range, for non-linear-light ("gamma encoded", although [that term is problematic]() spaces. It simply involves extending any linear portion near the origin, for the same distance in the negative; and then mirroring the curved portion.
The [sample code](https://drafts.csswg.org/css-color-4/#color-conversion-code) has that change, I need to check all of them have been done. The `transfer function` part of the [predefined colorspaces](https://drafts.csswg.org/css-color-4/#predefined) has not been done yet, but I will do so.
Specifications which reference these spaces and require clamped values are unaffected, because the clamping means they don't exercise that part of the EOTF; and everyone else gets it "for free" and it just works.
Linear-light versions get extended for free, because the EOTF is a straight line and extended it is still a straight line.
So I don't think there is a need to expose special `-extended` versions in CSS. Just make the regular ones extended.
On naming: I see the Canvas and WebGPU folks using things like `srgb-linear` while @samweinig used `linear-srgb` as an example. I have a _slight_ preference for putting the colorspace first so that they group together in indexes of terms.
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Received on Monday, 8 March 2021 20:13:52 UTC