Bug 305672

Summary: On some displays, CSS colors when used as layer backgrounds can still show as HDR
Product: WebKit Reporter: Simon Fraser (smfr) <simon.fraser>
Component: Layout and RenderingAssignee: Nobody <webkit-unassigned>
Status: NEW    
Severity: Normal CC: bfulgham, simon.fraser, webkit-bug-importer, zalan
Priority: P2 Keywords: InRadar
Version: WebKit Nightly Build   
Hardware: Unspecified   
OS: Unspecified   
See Also: https://bugs.webkit.org/show_bug.cgi?id=305683
Attachments:
Description Flags
Test none

Simon Fraser (smfr)
Reported 2026-01-16 15:52:30 PST
Created attachment 478057 [details] Test On a Studio Display, the left boxes in the attached testcase still show as HDR, even though we intend to clamp. `colorSpace.usesExtendedRange()` returns false for the Apple Studio Display, even though it has some HDR headroom. This causes `cachedSDRCGColorForColorspace()` and `createSDRCGColorForColorspace()` to not clamp as they should.
Attachments
Test (2.47 KB, text/html)
2026-01-16 15:52 PST, Simon Fraser (smfr) 		no flags
Details
View All Add attachment proposed patch, testcase, etc.
Radar WebKit Bug Importer
Comment 1 2026-01-16 15:52:35 PST
<rdar://problem/168331427>
Simon Fraser (smfr)
Comment 2 2026-01-16 15:53:38 PST
There has to be another HDR asset on the screen for that test case to show HDR.
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