## Chroma Key

The Chroma Key operator removes points by colour, the same way a green screen is keyed in video. Each point's colour is converted to HSV and points falling inside the key are discarded. It can be used to strip a backdrop or coloured props from a scene, or with **Invert** enabled to isolate them.
*[HSV]: Hue, Saturation, Value

### Operator Properties
- **Target Hue**: the centre of the key on the colour wheel, in degrees. The default of 140° targets green.
- **Hue Width**: the span of hues around the target that are keyed, in degrees.
- **Minimum Saturation**: points less saturated than this are never keyed, which protects greys and skin tones.
- **Minimum Value**: points darker than this are never keyed, which protects shadows.
- **Invert**: keep only the points inside the key and remove everything else.
- **Backend**: run the operator on the CPU or with CUDA.

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::: buttonlink
[View operator source](https://github.com/matth-av/pointcaster/blob/qt/src/plugins/operators/chroma_key/chroma_key_operator.cc)
:::