Halation
A soft reddish halo around intense highlights, caused by light spreading inside film stock.
See it
What it is
Halation is the warm red or orange halo that can form around strong highlights on film. Bright light passes through the emulsion, bounces off the back surface of the film base, and re-exposes the emulsion around where it entered, so a hard light source picks up a soft colored edge.
Kodak Vision3 500T is a reference for this look, while antihalation backing is the layer that suppresses it. For a digital match, isolate only the brightest areas, spread a soft warm copy, and blend it back lightly.
Gotcha: halation is not a red glow around every object. If the mask includes midtones or the halo is too wide, skin and shadows turn muddy and the result looks like a tinted blur.
Ask AI for it
Add film halation: isolate only the strongest highlights with a luminance key, expand and blur that mask by 8 to 20 pixels, tint it deep red-orange, and composite it behind the original highlights with screen blend at low opacity. Keep midtones, skin, and shadows clean.