> ## Documentation Index
> Fetch the complete documentation index at: https://comfytv.org/llms.txt
> Use this file to discover all available pages before exploring further.
# Keyer
> A flexible luma/chroma keyer with independent tolerance and softness on the low and high sides — pull mattes from brightness, a color, or a screen.
## What this node does
Keyer builds a matte from your footage using one of several strategies: key on **luminance** (brightness), on a specific **color**, on a green/blue **screen**, or pass through with **none**. Unlike a one-slider chroma key, it gives you a full keying curve — a center point plus separate tolerance and softness for the darker (lower) and brighter (upper) sides — so you can shape exactly which values are kept. It also has an angular despill for cleaning screen fringe.
Input and output are `COMFYTV_VIDEO`. It has a ▶ Run.
Like PIK Keyer, it picks its mode automatically: wire any of the side inputs (in/out mask or background) to run the full render; leave them empty and it runs a fast, previewable single-image key.
## When to use it
* You want to key on brightness (e.g. isolate highlights or shadows) rather than a color.
* A screen key needs asymmetric handling — tighter on one side of the threshold than the other.
* You need finer edge shaping than **Chroma Key** offers, but without a clean plate.
## Parameters
### mode
The keying strategy: `luminance` (default), `color`, `screen`, or `none`.
### key\_color
The reference color for `color`/`screen` modes. Hex, default `#000000`.
### The keying curve (softness\_lower, tolerance\_lower, center, tolerance\_upper, softness\_upper)
These five shape which values become the matte, from dark to bright:
* **softness\_lower** — feather below the lower tolerance. Range `-1.0`–`0.0`, default `-0.5`.
* **tolerance\_lower** — how far below center is still fully kept. Range `-1.0`–`0.0`, default `0.0`.
* **center** — the value the key is centered on. Range `0.0`–`1.0`, default `1.0`.
* **tolerance\_upper** — how far above center is still fully kept. Range `0.0`–`1.0`, default `0.0`.
* **softness\_upper** — feather above the upper tolerance. Range `0.0`–`1.0`, default `0.5`.
Widen the tolerances to keep more; increase the softness values to feather the transition.
### despill / despill\_angle
Spill suppression strength and its hue angle. `despill` ranges `0.0`–`2.0`, default `1.0` (0 = off). `despill_angle` ranges `0`–`180` degrees, default `120` (green). Set the angle toward your screen hue.
### output
`matte` (default) for a grayscale mask, `alpha` for real transparency, `premult` for premultiplied RGB, or `composite` to render over the background. (`alpha` needs the VP9 encoder — use `matte` if it errors.)
### Side inputs (optional)
* **video** — the plate to key.
* **in\_mask** — force areas fully opaque (keep).
* **out\_mask** — force areas fully transparent (remove).
* **bg\_video** — background used when `output` is `composite`.
## Outputs
| Output | Type | Meaning |
| --------- | --------------- | --------------------------------------- |
| **video** | `COMFYTV_VIDEO` | Keyed result in the chosen output form. |
## Tips
* For a luma key, start with `mode=luminance`, set `center` where the split should be, and open the tolerances/softness until the matte looks right.
* Wiring a side input switches to full-render mode; with none it stays a live-previewable key.
* To interoperate with native ComfyUI nodes, insert a **Bridge**. See [bridges.md](https://github.com/jtydhr88/ComfyTV/blob/main/docs/bridges.md).
## Related nodes
* **Chroma Key** — simpler single-color key.
* **PIK Keyer** — clean-plate / IBK-style keyer for the hardest screens.
* **Select0r** — color-space region keyer (RGB/ABI/HCI) with shape and edge controls.
* **Matte Monitor** — visualize how clean the resulting matte is.