Film grain / halation
Film-emulation texture: shifting grain across the image plus a soft warm halo where intense highlights bleed through the stock.
See it
What it is
Film grain and halation are two different clues that an image came from film stock. Grain is the changing texture created by the light-sensitive structure of the stock. Halation is the soft red or orange halo around strong highlights when light passes through the emulsion, reflects inside the film base, and exposes the surrounding area again. Kodak Vision3 is the usual grain reference; the strong red halation people emulate belongs to stocks whose anti-halation backing is gone, such as CineStill 800T.
Reach for them together when clean digital footage, CG, and composited elements need to feel photographed through one medium. Add grain after the final resize so its scale matches the delivery, and derive the halation only from the brightest parts of the graded image.
Gotcha: grain is not stationary noise, and halation is not a red outer glow around every edge. A frozen overlay sticks to the screen instead of the image, while a broad halation mask muddies skin and shadows. Judge both at playback size, because zooming into a still encourages effects that are much too strong.
Ask AI for it
Create a restrained 35mm film pass in Adobe After Effects. Apply Add Grain after the final resize, match the grain size to the output, and keep its intensity low enough that faces stay clean. For halation, make a luminance key from only the strongest highlights, expand it 8 to 16 pixels, blur it, tint it red-orange, and composite it above the source with Screen at 15 to 25 percent opacity. Keep midtones and shadows out of the halation mask.