HDR‑Infused Emoji

Original Article ↗ Hacker News Discussion ↗

Browser and platform support

  • Works reliably in Chrome (desktop and Android) and Electron apps like Slack; many people report blindingly bright emojis there.
  • Safari: HDR video works; HDR images are in Technology Preview behind a flag. Shipping Safari on macOS generally doesn’t show this PNG-based trick yet (seen as intentional and low‑priority, not impossible).
  • Firefox has no real HDR support on most platforms despite work being discussed for years; several users see only flat white or muted colors.
  • Linux users report no effect in any tested browser despite OS/monitor HDR support.
  • Some Android users see it in Chrome/Vivaldi; others don’t, suggesting device/OS/version variance.

Potential for abuse and user‑hostile design

  • Many worry this will be used like autoplay audio / “loudness war” in audio: brighter‑than‑white elements to grab attention, especially in ads or chat apps.
  • Some consider Safari’s initial reluctance with HDR images “the correct behavior” for that reason.
  • Others counter that the web already allows very bothersome visuals and HDR images are not qualitatively worse.

How it works and technical notes

  • Trick: encode images in an HDR/wide‑gamut color space (e.g., Rec. 2020) so highlights exceed the usual #ffffff SDR white, while the rest of the page stays SDR.
  • On HDR displays, OS/browser tone‑mapping boosts those pixels, so emojis appear brighter than the brightest normal UI white.
  • CSS and spec work exists to control dynamic range per element, and to clamp content back to SDR if desired.
  • Some describe editorial uses: subtle halos or “gilded” accents via HDR video or HDR PNGs for tasteful emphasis.

Perception, brightness, and implementation quirks

  • Several users perceive the rest of the page dimming when HDR elements appear. Disagreement whether macOS actually darkens SDR content or whether this is a contrast illusion; some technical back‑and‑forth cites Apple’s EDR behavior.
  • HDR behavior varies by panel (XDR vs MacBook screens, TVs, phones). Window size/peak brightness constraints matter.
  • YouTube HDR examples prompt questions about how content is shot, encoded (HLG, HDR10, Dolby Vision), and preserved through editing/upload.

Use cases: fun vs annoyance and accessibility

  • Many enjoy using this for Slack emojis and profile pics or as a visual “wow” effect; others report strong peer pressure to remove them because they dominate channels.
  • People with light sensitivity describe sudden HDR flashes as physically painful and want system‑wide ways to disable HDR, especially on Android.
  • One observation: screenshots of these pages lose the HDR effect, potentially allowing hard‑to‑capture content.

Debate: HDR as advancement or gimmick

  • Supporters call HDR one of the biggest display improvements in years, especially for movies and games, valuing higher peak brightness and better dark scenes.
  • Skeptics liken it to 3D TVs or “surround sound for most people”: more marketing than meaning, or simply “too much brightness.”
  • Some note HDR’s real benefits are wider dynamic range and bit depth, not just “turning the brightness up.”

Control and mitigation

  • macOS: HDR can be effectively disabled by choosing SDR/sRGB display presets or toggling HDR options on certain displays.
  • Windows HDR is widely criticized as clumsy, requiring manual mode switches and producing bad mappings; screenshots/capture are problematic.
  • Browsers: Chrome can be forced to sRGB via chrome://flags/#force-color-profile. Slack inherits whatever the underlying engine does; users ask for app‑level toggles.
  • A GitHub project shows how to block HDR emojis, and commenters trade tips on OS/browser HDR test pages and switches.