luminance mask
The image grades itself. The mask reads the light already in the frame — shadows fall to one treatment, highlights lift to another — so the picture tells you where it wants to be touched.
What it’s for
A colourist working a film print never touches the whole frame at once — they push the shadows somewhere cool, let the skin tones breathe, roll the highlights warm. The luminance mask gives you that same hand. It reads the brightness already living in the source and turns it into the mask, so an effect lands only where the light invites it.
low is the floor: anything darker stays masked
out. high is the ceiling: anything brighter is
fully in. Between them, gamma bends the falloff
— a gentle S-curve to protect the midtones, or a hard
knee to grab only the specular hits. The mask becomes a
tonal selection that moves with the picture, frame by frame.
Reach for this when: you want to push only the darks toward green and only the highlights warm; a glow should bloom from the bright areas alone; a grain pass should crawl in the shadows the way it does on real film stock.
Where it lives in the app
Add from the Masks panel. The mask appears as its own layer
on the timeline; assign it to one or more effects by setting
their target to point at this mask layer.
Parameters
| Key | Range | Default | Effect |
|---|---|---|---|
low | 0–1 | 0.1 | Below this stays masked out |
high | 0–1 | 0.9 | Above this is fully in |
gamma | 0.1–4 | 1 | Curve of the falloff |
Pairs well with
- color grade — split-tone the darks one way and the highlights another. A whole mood built out of light that was already there.
- phosphor CRT glow — bloom blooms only from the bright hits, the way a real tube smears its brightest pixels.
- film grain — noise crawls in the shadows and stays clean in the highlights, exactly like the emulsion it’s imitating.
- chromatic aberration — colour fringing keyed to the highlights reads as lens flare rather than a glitch.