How to Use the OBS Luma Key Filter
The Luma Key filter changes transparency according to brightness. It can remove dark or bright areas from a source, such as a simple black or white background in a graphic.
Unlike Chroma Key, it does not select a background by color. If the subject contains similar brightness values, those parts can disappear too.
Choose suitable material
Luma key works best when the area you want to remove is clearly separated in brightness from the area you want to keep.
For example, a bright graphic on a dark background may be easier to separate than a person wearing dark clothing in a dark room. Luma key does not understand which pixels belong to a person.
Add the filter
- 1.Select the visual source in OBS.
- 2.Right-click it and open Filters.
- 3.Under Effect Filters, choose + → Luma Key.
- 4.Adjust the controls while watching the preview.
Place a contrasting background source underneath while testing. This makes unwanted transparent areas easier to spot.
Adjust brightness boundaries
Luma Min and Luma Max control the brightness range used by the filter. Raising the minimum can remove darker pixels; lowering the maximum can remove brighter pixels.
Move one control at a time. Watch the whole source, including hair, clothing, shadows, and highlights, rather than concentrating only on the background.
The corresponding Smooth controls soften the transition at the removed areas. Too little smoothing may leave harsh edges, while too much can make detail partially transparent.
Check motion and changing light
Record movement and any changes in lighting. A key that looks acceptable in a still preview may break up when the camera exposure changes or the subject moves into shadow.
If useful detail disappears, relax the threshold or use another approach. Chroma Key suits a distinct background color, while an image mask suits a fixed geometric opening. Neither is automatically interchangeable with luma key.
Keep a clean version
Disable the filter to compare with the unmodified source. If you reuse the same source in several scenes, check those scenes too because source-level filters are shared.
For a simple transparent graphic, an original PNG with a proper alpha channel may be cleaner than trying to remove a baked-in background.