Add film halation to your photos

What halation is

Halation is the glow film gets around very bright lights. Light passes through the emulsion, bounces off the back of the film and comes up again a little way off, where it reaches the red-sensitive layer first. So street lights, sun on water and bright windows get a soft red to orange halo, while the rest of the picture stays as it was. A digital sensor has no such layer, which is why the glow reads as film.

How the tool makes it

1. It finds the lights: everything above the Brightness level, with clipped lamps counting far more than a bright wall, and a lamp that stands well above a dark room counting even when it is not clipped.
2. It spreads that light outwards by the Radius, measured in pixels of your full-size photo.
3. Only the light that spills onto the surroundings shows, so the glow lands around lights and along bright edges, never on a lamp's face or across an evenly bright sky.
4. It adds the glow in the colour you chose and holds back the colour's opposite, so a halo over a white wall still reads red. Everything the glow does not reach is left exactly as it was.