Show HN: Make images render brighter than white by abusing Rec.2100 PQ profiles
a day ago
- #HDR imaging
- #display technology
- #image processing
- SDR white (about 200 nits) is not a display's maximum brightness; HDR-capable panels can output 1,000–1,600 nits, leaving headroom.
- A Rec.2100 PQ color profile embedded in an 8-bit JPEG tricks color-managed renderers into displaying bright values in this headroom, making images glow brighter than the interface.
- Platforms like LinkedIn preserve ICC profiles through re-encoding, allowing the technique to work, though it fails with screenshots, re-saving, or compression.
- Superwhite properly processes images per pixel: decoding sRGB to linear light, converting primaries, masking white regions, boosting brightness, and encoding with PQ.
- The technique is a novelty with limited lifespan, as platforms may clamp brightness like they did for HDR video; subtle use is recommended for best effect.