[csswg-drafts] [css filters] supported values for the "in" attribute (#13384)

karlcow has just created a new issue for https://github.com/w3c/csswg-drafts:

== [css filters] supported values for the "in" attribute ==
the `in` attribute identifies input for the given filter primitive.

It is defined in https://drafts.csswg.org/filter-effects/#element-attrdef-filter-primitive-in as:

```
in = "SourceGraphic | SourceAlpha | BackgroundImage | BackgroundAlpha | FillPaint | StrokePaint | <filter-primitive-reference>"
```
only 
* `SourceGraphic`, 
*  `SourceAlpha` 
 
are supported by browsers to the best of my knowledge

Even WPT is minimal on the topic.
https://wpt.fyi/results/css/filter-effects


Should it be removed from the spec?

Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/13384 using your GitHub account


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Received on Thursday, 22 January 2026 23:27:15 UTC