# Erode

> Erode (blur): moves the edges of a black and white matte by size pixels (positive shrinks it; the default is -1, which grows it) through a blur, with a soft one-pixel edge; blur softens the result and

Erode (blur): moves the edges of a black and white matte by size pixels (positive shrinks it; the default is -1, which grows it) through a blur, with a soft one-pixel edge; blur softens the result and quality sets the blur quality. Grey solid areas change, as in Nuke.

| Node | Erode |
|---|---|
| Menu | Filter › Erode (blur) |
| **Names in each format** | |
| .oink comp (JSON) | `"type": "OC_N_erode"` |
| .nk script | `Erode` ([how .nk import works](/docs/nuke-users/nk-import)) |
| Python | `nuke.createNode("Erode")` |
| Assistant (MCP) | `create_node(type="Erode")` |
| Tab search | `erode` |

![Erode properties](/shots/nodes/erode@2x.webp)

## Inputs and outputs

| Port | Name | Type |
|---|---|---|
| input 0 | Image | image |
| input 1 | mask | image |
| output 0 | Image | image |

## Knobs

Panel tab **Erode**, in panel order.

| Knob | Label | Type | Default | Range / values | .nk knob | Description |
|---|---|---|---|---|---|---|
| `channels` | channels | menu | `alpha` | rgba, rgb, alpha, all, none |  | Layer the op applies to: rgb, rgba, alpha, all, none, <layer> or <layer>.<ch> |
| `size` | size | float | `-1` | -20 to 20 | `size` |  |
| `blur` | blur | float | `0` | 0 to 100 | `blur` |  |
| `quality` | quality | float | `15` | 1 to 100 (integer) | `quality` |  |
| `mask_channel` | mask | menu | `none` | none, rgba.alpha, rgba.red, rgba.green, rgba.blue |  | Mask channel, e.g. rgba.alpha (none = no mask) |
| `inject` | inject | bool | `false` |  |  | Copy the mask into mask.a for nodes downstream |
| `invert_mask` | invert | bool | `false` |  | `invert_mask` |  |
| `fringe` | fringe | bool | `false` |  |  | Only apply the effect at the edges of the mask |
| `mix` | mix | float | `1` | 0 to 1 | `mix` |  |

### Other knobs (Python, .nk and the assistant; not on the panel)

| Knob | Label | Type | Default | Range / values | .nk knob | Description |
|---|---|---|---|---|---|---|
| `gl_color` | Viewer Controls Color | float ×3 | `0, 0, 0` | 0 to 1 |  |  |
| `postage_stamp_frame` | Static Frame | int | `1` | -2147483648 to 2147483647 |  |  |
| `lifetimeStart` | Lifetime Start | int | `0` | -2147483648 to 2147483647 |  |  |
| `lifetimeEnd` | Lifetime End | int | `100` | -2147483648 to 2147483647 |  |  |
| `useLifetime` | Use Lifetime | boolean | `false` |  |  |  |
| `cached` | Cached | boolean | `false` |  |  |  |
| `bookmark` | Bookmark | boolean | `false` |  |  |  |
| `dope_sheet` | Dope Sheet | boolean | `false` |  |  |  |
| `clone_group` | Clone Group | string |  |  |  |  |
| `link_source` | Link Source | string |  |  |  |  |
| `link_overrides` | Link Overrides | string |  |  |  |  |
| `split_views` | Split Views | string |  |  |  |  |
| `unpremult` | (Un)premult by | enum | `none` | none, rgba.alpha |  |  |
| `invert_unpremult` | invert | boolean | `false` |  |  | (Un)premultiply by 1 - alpha |


---
Sources: opencomp_core/nodes/filter/erode.py, opencomp_electron/src/components/properties/knobSchema.ts, opencomp_core/nodes/help/erode.md, opencomp_core/nk/mapping.py