Bug 258686

Summary:

[iOS 17] PNG image transparency is broken

Product:

WebKit

Reporter:

Jacob Goldman <jmgoldman>

Component:

Images

Assignee:

Nobody <webkit-unassigned>

Status:

RESOLVED MOVED

Severity:

Major

CC:

sabouhallawa

Priority:

Version:

Safari 17

Hardware:

iPhone / iPad

OS:

Other

Attachments:

Description	Flags
iOS 17.0 in Safari navigated to https://jsbin.com/rowohenaji?html,css,output	none

Description Jacob Goldman 2023-06-29 11:19:45 PDT

Created attachment 466867 [details]
iOS 17.0 in Safari navigated to https://jsbin.com/rowohenaji?html,css,output

PNGs with any alpha channel set below around 0.5 has no effect. Pixels with an alpha channel of 0 are still visible, breaking transparent backgrounds. All PNGs seem to be impacted across the entire web.

Example: https://jsbin.com/rowohenaji?html,css,output. See attachment for iOS 17.0 reproduction showing pink overlays on all elements.

Only reproducible on iOS 17.0, cannot reproduce on macOS Ventura 13.4 with Safari Release 172 (Safari 17.0, WebKit 18616.1.17.3). I am unable to reproduce this on iOS outside of WebKit (verified in Safari and WKWebView).

See also:
* highly visible bug in Google Ads: https://redd.it/14kda07
* similar bug reported on Amazon.com: https://bugs.webkit.org/show_bug.cgi?id=258454.

Comment 1 Alexey Proskuryakov 2023-06-29 14:58:35 PDT

Thank you for the report! This is an issue below WebKit, tracked by Apple internally as rdar://110822373.