Halation
Also called: film halation, red glow, highlight glow, film bloom
Halation is the red-orange glow around bright highlights on film. Learn why light bounces inside the stock and how to build it with Super8 Film Lab.
WHAT CAUSES IT
Halation is the glow that forms around bright highlights on photographic film when light passes through the emulsion, reflects off the back of the film base, and exposes the emulsion a second time. A bright source, such as a window, a lamp, or a specular reflection, delivers more light than the emulsion can absorb on its first pass. The surplus travels through the layers and the transparent base until it reaches the back of the film, where it scatters off the pressure plate or the base surface. Some of it returns to the emulsion and exposes it in a ring around the original point. The color of the ring is warm because the red-sensitive layer sits at the bottom of the stack, closest to the base, and because red light penetrates deepest. Many motion picture stocks carry an antihalation layer, which absorbs the excess light, and where it is weak or missing, the glow is strong. Halation is a property of the film itself, so it stays close to the edge of bright areas and does not wrap the whole frame like lens bloom.
WHAT IT LOOKS LIKE
A soft red, orange, or warm yellow fringe that surrounds the brightest parts of the picture, such as a lamp, a window, a white shirt, or sunlight on a rooftop. The glow is faint at a distance and strongest right at the edge of the highlight, and it spreads a few percent of the frame width. The core of the highlight stays white, and the edges seem to burn into the dark surroundings. In a dark scene with bright points, the effect is clearly visible, such as streetlights with a warm ring. The rest of the picture remains sharp, which separates halation from overall diffusion.
WHERE YOU SEE IT
Night scenes on film, stage and concert footage, shots with practical lights in frame, and films shot on stock without a strong antihalation backing. It is part of the look of 1970s cinema, home movies shot against a window, and modern films that deliberately use film emulation. In digital work, halation is added to highlights to make video feel photochemical, often together with grain and gate weave.
RECREATE IT
SUPER8 FILM LAB
CONTROLS HALATION, BLOOM, GRAIN
HALATION controls the warm glow that clings to highlights, so raise it until bright points have a visible red-orange rim and stop before the entire frame is washed. BLOOM adds the neutral lens-style glow, and the two together are common on real film, but keep BLOOM lower so halation stays distinct. Add a small amount of GRAIN so the glow does not look digitally smooth.
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HOW TO MAKE IT IN AFTER EFFECTS
1. Render your footage in SUPER8 FILM LAB, a standalone Windows application, not an After Effects plugin. 2. Choose a shot with bright highlights, such as windows, lamps, or reflections, and raise HALATION until you see the warm ring around them. 3. Keep BLOOM lower than HALATION so the red-orange fringe remains. 4. Export the halation pass and the bloom pass as separate clips; the app writes grain, bloom, halation and matte passes as individual files with blend instructions. 5. Bring the clips into After Effects with your footage, and stack the halation clip above the picture using the blend mode given in the export instructions. Screen is a typical starting point for a glow layer. 6. Lower the opacity of the halation layer to taste, and use the matte pass if you want to limit the glow to certain areas. 7. If you need to change the strength later, adjust the layer opacity instead of re-rendering. 8. Check the result in a dark scene at full size, where the effect is easiest to judge. 9. Keep the grain layer on top so the glow is textured.
QUESTIONS
- Why is halation red?
- The red-sensitive layer lies deepest in the emulsion, nearest the film base, so it receives the light that reflects back from behind. Red light also passes through the layers most easily. The reflected exposure therefore falls mostly on the red layer.
- What is the difference between halation and bloom?
- Halation is a film-internal reflection that gives a red-orange rim around highlights. Bloom is a lens or diffusion glow that is usually neutral or the color of the highlight. Real footage can have both at once. A quick test is color: a warm red or orange rim points to halation, while a white or tinted haze across the whole bright area is bloom.
- Do all film stocks show halation?
- Most stocks have some, but its strength depends on the antihalation layer. Stocks with weak or removed backing show strong halation, while modern motion picture stocks with a good backing show very little. Stocks used in cheap cartridges or older emulsions are the usual suspects when halation is dramatic.
- Can digital cameras have halation?
- Not in the film sense. A sensor has no emulsion to reflect light back through. Digital halation is a post effect that copies the look by blurring highlights and tinting them warm. Because the glow is added in software, you control how far it spreads and how red it is, which real film never allowed.