LAM Guides · Film effects
A lot of "vintage" filters do exactly one thing: drop the saturation and throw a layer of random noise over the whole frame. The result looks old, but it doesn't look like real film — because film grain isn't uniform across a frame, and there are at least two other phenomena a simple filter never models: halation and light leak. Knowing these three helps you spot where a fake film look falls apart.
On real film, grain comes from silver-halide particles in the emulsion developing unevenly under light. The detail most filters get wrong: grain amount isn't the same across every bright and dark region of the frame. Highlights and shadows typically show different amounts of grain, faster (higher-ISO) film stocks show more grain than slower ones, and the visible grain shifts with local brightness — not a flat noise layer smeared evenly across the whole frame, which is the shortcut a lot of filters take.
How to spot a fake film look: look at the darkest and brightest parts of a photo. If the "noise" looks identical in both, it's likely a simple noise overlay, not grain modelled against actual brightness.
Halation happens when strong light (a lamp, the sun, a neon sign) passes through the film emulsion, reflects off the backing layer, and scatters back outward as a soft glow around that light source — usually with a warm red or orange tint. That's why film photos of neon signs at night show a warm halo around each light, unlike a typical digital photo where a bright spot just clips to plain white with no halo at all.
Halation is a position-dependent effect (it depends on where the bright spots are in the frame), so it can't be modelled with a single whole-frame colour adjustment — it needs to know exactly which pixels are bright to bloom the right ones.
On real film cameras (especially older ones, plastic-bodied ones, or anything hand-loaded), light can leak in through a gap in the film compartment, creating an unpredictable colour streak — usually orange, red, or yellow — running across part of the frame. It's random in shape and position, never repeating the same way twice. It used to be considered a defect nobody wanted, and became part of the signature look of disposable and lomography-style film photography instead.
Grain depends on local brightness. Halation depends on where the bright spots are. Light leak is an independent overlay that doesn't depend on the image content at all. Three different mechanisms — which is why in LAM they're computed as three separate layers, added in the correct physical order (colour grade → skin tone → halation → light leak → grain), rather than one "vintage" filter applied in a single pass. That's how one photo can carry all three characteristics at once without any of them fighting the others.