Add the red halo those films put round bright lights. Choose a preset, then adjust strength. Photos stay on your device.
JPEG, PNG, or anything your browser can open. Exports at full resolution; JPEG export keeps the source JPEG's EXIF and colour profile when present.
I shoot CineStill 800T and 400D on film and a GFX 50R digitally, and wanted the one thing the camera cannot do: the red halo those stocks put round every light. Nothing I found did it the way the film does, so I measured my own scans and built this. It is free, it runs in your browser, and your photos never leave your device. I also shoot various BwXX variants and while the halo isn't red it does produce haloing so a BwXX preset is included as well.
While this site and the code / math behind the conversion was built with Claude there is no AI processing of your photos at all.
Source, the Python version, and the film measurements the presets were fitted to: github.com/farewell-ladmin/halation.py (MIT).
On remjet-less film, light that gets through the emulsion bounces off the base and re-exposes the red-sensitive layer from behind. The ring sits tight against the light and is gone within about 1% of the frame width. Measured on 36 CineStill scans, the red-to-green ratio by distance from a clipped light (1.0 means red and green are equal):
| stock | 0.2% | 0.3% | 0.6% | 1.0% |
|---|---|---|---|---|
| 400D | 1.40 | 1.49 | 1.10 | 1.06 |
| 800T | 1.26 | 1.28 | 1.16 | 1.07 |
| 500T (has remjet) | 1.05 | 1.10 | 1.14 | 1.06 |
BwXX is CineStill's respooled Kodak 5222 (Midwest Film Co's Double-X and Cine 800 are the same stock). It has no remjet, so lights bloom, but a grey-base anti-halation layer keeps it soft and neutral rather than a red ring: measured on 36 frames, the glow above the surroundings is still a fifth of the headroom 1% out and a tenth at 2%, where the colour stocks have long gone dark. The BwXX preset converts the photo to black and white and adds that glow.
The tool finds the clipped lights, spreads their energy at that radius, and adds red light, with a little green and never blue, which the film's yellow filter layer absorbs. Adding rather than blending is why it is vivid against the dark and gentle inside bright glow, like the film. Photos with no clipped light get no ring, which is also what the film does.