W3C home > Mailing lists > Public > www-style@w3.org > March 2016

Re: [css-color] wider/deeper colors

From: Simon Fraser <smfr@me.com>
Date: Tue, 22 Mar 2016 22:19:32 -0700
Cc: Florian Rivoal <florian@rivoal.net>, aaron.www-style-@infinite-source.de, www-style list <www-style@w3.org>
Message-id: <A7F78C10-E3AE-4B7F-941C-8DC85B9137BE@me.com>
To: Rik Cabanier <cabanier@gmail.com>
> On Mar 22, 2016, at 6:54 pm, Rik Cabanier <cabanier@gmail.com> wrote:
> On Tue, Mar 22, 2016 at 5:49 PM, Simon Fraser <smfr@me.com <mailto:smfr@me.com>> wrote:
> The 4k/5k iMac and the new iPad Pro composite in unclipped sRGB, and map to the display colorspace (DCI-P3) at the end. We (WebKit) have no control over the colorspace used for compositing, so we don’t have knobs to tune here.
> Why can't you use colorsync?
> https://developer.apple.com/library/ios/technotes/tn2313/_index.html#//apple_ref/doc/uid/DTS40014694-CH1-FRAMEWORKS_FOR_COLOR_MATCHING_WHEN_RENDERING_TO_THE_DISPLAY  <https://developer.apple.com/library/ios/technotes/tn2313/_index.html#//apple_ref/doc/uid/DTS40014694-CH1-FRAMEWORKS_FOR_COLOR_MATCHING_WHEN_RENDERING_TO_THE_DISPLAY>

ColorSync is about doing color matching, not composting. To be clear, when I say “compositing” here I mean what happens when you paint non-opaque images and colors on top of each other, and when the GPU composites non-opaque textures.

> Also, if you composite in unclipped sRGB, how are you honoring images with a high gamut profile such as p3 or AdobeRGB?

Because it’s unclipped? Compositing happens in 10-bit or half-float textures which may contain < 0 or > 1 values. A P3 image is mapped into this unclipped sRGB space for compositing, then the final result is mapped into Display-P3 at the end.


Received on Wednesday, 23 March 2016 05:20:03 UTC

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