- From: Chris Lilley via GitHub <sysbot+gh@w3.org>
- Date: Tue, 19 Apr 2022 16:29:31 +0000
- To: public-css-archive@w3.org
So: given that - SVG filters already operate in linear-light sRGB, and the sRGB to XYZ conversion matrix is [baked into the spec](https://drafts.fxtf.org/filter-effects/#attr-valuedef-type-saturate) with the saturation and luminance operators - but they assume 8-bit and hard clamp at 0 and 255 on each stage in the filter chain so can't do WCG - _extended_, linear-light sRGB is [already defined in CSS color 4 as `srgb-linear]()`](https://drafts.csswg.org/css-color-4/#predefined-sRGB-linear) and _can_ represent wide color gamut colors, such as P3 colors - plus it is already proposed for use in Canvas for WCG - plus there is existing GPU hardware support for extended, linear-light sRGB - [`color-interpolation filters` exists](https://drafts.fxtf.org/filter-effects/#ColorInterpolationFiltersProperty) in Filter Effects 1 with the values `auto | sRGB | linearRGB` and the initial value is `linearRGB` Then I propose to extend `color-interpolation filters` to take an additional value with a definition link to CSS color 4, and that value is explicitly an extended, WCG space and has a 16-bit precision requirement. Extended means that negative values, and values greater than 1.0, are allowed. For example `color(display-p3 0 1 0)`, which is outside the sRGB gamut, is `color(srgb-linear -0.225 1.0421 -0.079)` This will add WCG support to SVG filters, is opt-in so existing content continues to render the same, and can also be opted into to get the improved precision (8 bits linear light has visible banding) even for sRGB-only content. The new value could be `sRGB-linear` for compatibility with Canvas and with CSS Color 4, although above I suggested `linearRGBextended` which I could also live with. I'm guessing this would go in [Filter Effects 2](https://drafts.fxtf.org/filter-effects-2/) ? -- GitHub Notification of comment by svgeesus Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/7100#issuecomment-1102853396 using your GitHub account -- Sent via github-notify-ml as configured in https://github.com/w3c/github-notify-ml-config
Received on Tuesday, 19 April 2022 16:29:32 UTC