Post #1825503
2026-04-16 08:53 UTC
The AppIcon.icns file only has flat 8-bit sRGB PNGs, so it doesn’t include any HDR data. The XDR effect actually comes from Assets.car, which contains an AppIcon.iconstack, a new layered icon format since macOS 14 (Sequoia). The Dock, Finder, and Quick Look in the app bundle all use .iconstack, while Quick Look uses the AppIcon.icns with the flat sRGB image. (2/6)
Replies (1)
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@vancura@mastodon.design 2026-04-16 08:53
HDR brightness isn’t stored as pixel data. Instead, it appears at render time based on layer properties in the .iconstack. These include LayerHasLightingEffects (adds realistic lighting to vector shapes), LayerBlendMode "PlusL" (linear additive, which combines overlapping brightness), and the LayerHasSpecular and LayerGathersSpecularByElement flags (control shiny highlights on elements). (3/6)