[Webkit-unassigned] [Bug 272017] New: [CSS Filters] brightness() causes high-brightness HDR flicker

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=272017

            Bug ID: 272017
           Summary: [CSS Filters] brightness() causes high-brightness HDR
                    flicker
           Product: WebKit
           Version: Safari 17
          Hardware: Mac (Apple Silicon)
                OS: All
            Status: NEW
          Severity: Normal
          Priority: P2
         Component: CSS
          Assignee: webkit-unassigned at lists.webkit.org
          Reporter: michoel at hey.com

Created attachment 470715

  --> https://bugs.webkit.org/attachment.cgi?id=470715&action=review

Shows the unexpected behavior in Safari 17.4, and the the expected behavior in a Chromium browser

I've found an unusual behavior in Safari 17.4.

When the brightness() filter is applied to an element, for a split second the element's brightness becomes extremely bright, before settling down to the brightness specified by the filter. 
See the attached video. The issue does not appear in screen captures, so I took a video of the screen using a phone.

For a moment the element gets so bright that it appears "whiter" than every other element onscreen. It seems to activate the HDR layer of the display panel for moment (I'm using a 2021 MacBook Pro with M1 Pro).
It then "quiets down" and adopts the correct brightness value specified by the CSS filter.
The effect isn't as bad on iOS, but is definitely still there.
The effect does not appear in screen captures, so I wonder if it's triggering something in the OS or hardware level.


I've attached a video showing this issue.
The URL I used for testing is here:
https://developer.mozilla.org/en-US/docs/Web/CSS/filter-function/brightness

Let me know if there's any way I can help!
– Michoel

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