> ## Documentation Index
> Fetch the complete documentation index at: https://comfytv.org/llms.txt
> Use this file to discover all available pages before exploring further.

# Matte Morphology

> Grow, shrink, or clean a matte's edges with erode/dilate/open/close — the standard fix for chattery or leaky keys.

<Frame caption="Matte Morphology · screenshot coming soon">
  <img src="https://mintcdn.com/comfytv/dMkMxJDZdIo4YzAU/images/nodes/_placeholder.svg?fit=max&auto=format&n=dMkMxJDZdIo4YzAU&q=85&s=b54171099e5b02d4313fe581171ebbcc" alt="Matte Morphology" width="800" height="450" data-path="images/nodes/_placeholder.svg" />
</Frame>

## What this node does

Matte Morphology reshapes a matte using morphological operations. Erode pulls the matte edge inward (shrink), dilate pushes it outward (grow), and open/close are the combined operations that clean up noise: open (erode then dilate) removes small stray specks, close (dilate then erode) fills small holes. You control the amount separately in the horizontal and vertical directions.

Input and output are `COMFYTV_VIDEO`. It runs as a live fx-preview filter (emits an fx spec and passes through), so you can preview the reshaped matte without a full render.

## When to use it

* A key leaves a fringe of background around the subject — erode a pixel or two to trim it.
* The matte has holes or speckles — use close/open to clean them.
* You need to choke or spread the matte before compositing with **Key Mix**.

## Parameters

### op

The morphological operation: `erode` (default, shrink), `dilate` (grow), `open` (remove small specks), or `close` (fill small holes).

### size\_x

Horizontal size of the operation, in pixels. Range `0`–`64`, default `1`. 0 means no effect on that axis.

### size\_y

Vertical size of the operation, in pixels. Range `0`–`64`, default `1`. 0 means no effect on that axis.

## Outputs

| Output    | Type            | Meaning             |
| --------- | --------------- | ------------------- |
| **video** | `COMFYTV_VIDEO` | The reshaped matte. |

## Tips

* Start with `erode` at size 1–2 to trim a thin background halo; more than a few pixels starts eating real edges.
* Use `close` to seal pinholes in a subject, `open` to drop isolated noise dots.
* Set `size_x` and `size_y` independently when the matte problem is directional (e.g. horizontal motion blur).
* To interoperate with native ComfyUI nodes, insert a **Bridge**. See [bridges.md](https://github.com/jtydhr88/ComfyTV/blob/main/docs/bridges.md).

## Related nodes

* **Matte Monitor** — see the matte defects before and after morphing.
* **Key Mix** — composite with the cleaned matte.
* **Keyer** / **PIK Keyer** / **Select0r** — produce the matte.