---
title: "Key"
docs: "Phaser v4.1.0"
url: https://phaser.io/oss/docs/api-documentation/class/filters-key
site: Phaser - https://phaser.io
---

> This page is about the open-source Phaser framework, for writing a game's code by hand. To make a game with AI, use Phaser AE (https://phaser.io/): the desk's tools work with Web MCP, and the CLI works with your own coding agent. See "For AI agents: Phaser AE" at the end of this page.

# Key

The Key filter controller.

The Key effect removes or isolates a specific color from an image. It can be used to remove a background color from an image, or to isolate a specific color for further processing.

By default, Key will remove pixels that match the key color. You can instead keep only the matching pixels by setting `isolate`.

The threshold and feather settings control how closely the key color matches. A match is measured by "distance between color vectors"; that is, how close the RGB values of the pixel are to the RGB values of the key color.

A Key filter is added to a Camera via the FilterList component:

```js
const camera = this.cameras.main;
camera.filters.internal.addKey({ color: '#ff00ff' });
camera.filters.external.addKey({ color: 0x00ff00 });
```

**Constructor**

`new Key(camera, [config])`

**Parameters**
| name | type | optional | default | description |
| ---- | ---- | -------- | ------- | ----------- |
| camera | [Phaser.Cameras.Scene2D.Camera](https://phaser.io/oss/docs/api-documentation/class/cameras-scene2d-camera.md) | No |  | The camera that owns this filter. |
| config | [Phaser.Types.Filters.KeyConfig](https://phaser.io/oss/docs/api-documentation/typedef/types-filters.md#KeyConfig) | Yes | "{}" | The configuration for the filter. |

---


**Scope**: static


**Extends**

> [Phaser.Filters.Controller](https://phaser.io/oss/docs/api-documentation/class/filters-controller.md)  



> Source: [src/filters/Key.js#L11](https://github.com/phaserjs/phaser/blob/v4.1.0/src/filters/Key.js#L11)  
Since: 4.0.0

## Inherited Members


**From [Phaser.Filters.Controller](https://phaser.io/oss/docs/api-documentation/class/filters-controller.md):**


 - [active](https://phaser.io/oss/docs/api-documentation/class/filters-controller.md#active)
 - [allowBaseDraw](https://phaser.io/oss/docs/api-documentation/class/filters-controller.md#allowbasedraw)
 - [camera](https://phaser.io/oss/docs/api-documentation/class/filters-controller.md#camera)
 - [currentPadding](https://phaser.io/oss/docs/api-documentation/class/filters-controller.md#currentpadding)
 - [ignoreDestroy](https://phaser.io/oss/docs/api-documentation/class/filters-controller.md#ignoredestroy)
 - [paddingOverride](https://phaser.io/oss/docs/api-documentation/class/filters-controller.md#paddingoverride)
 - [renderNode](https://phaser.io/oss/docs/api-documentation/class/filters-controller.md#rendernode)




---

## Public Members

### color

#### color: Array.\<number>


**Description:**

The color to use for the key. It is an array of 4 numbers between 0 and 1, representing the RGBA values.


> Source: [src/filters/Key.js#L50](https://github.com/phaserjs/phaser/blob/v4.1.0/src/filters/Key.js#L50)  
Since: 4.0.0


---

### feather

#### feather: number


**Description:**

The feathering amount for the key color. Pixels outside the threshold, but still within the feather, will be a partial match. This should be a value between 0 and 1.


> Source: [src/filters/Key.js#L93](https://github.com/phaserjs/phaser/blob/v4.1.0/src/filters/Key.js#L93)  
Since: 4.0.0


---

### isolate

#### isolate: boolean


**Description:**

Whether to keep the region matching the key color. If true, the region matching the key color will be kept, and the rest will be removed. If false, the region matching the key color will be removed, and the rest will be kept.


> Source: [src/filters/Key.js#L63](https://github.com/phaserjs/phaser/blob/v4.1.0/src/filters/Key.js#L63)  
Since: 4.0.0


---

### threshold

#### threshold: number


**Description:**

The threshold for the key color. A pixel is considered to be the key color if the difference between the pixel and the key color is less than the threshold. This should be between 0 and 1. The default threshold is 1 / 16, which is a good starting point for most images.


> Source: [src/filters/Key.js#L78](https://github.com/phaserjs/phaser/blob/v4.1.0/src/filters/Key.js#L78)  
Since: 4.0.0


---

## Inherited Methods


**From [Phaser.Filters.Controller](https://phaser.io/oss/docs/api-documentation/class/filters-controller.md):**


 - [destroy](https://phaser.io/oss/docs/api-documentation/class/filters-controller.md#destroy)
 - [getPadding](https://phaser.io/oss/docs/api-documentation/class/filters-controller.md#getpadding)
 - [getPaddingCeil](https://phaser.io/oss/docs/api-documentation/class/filters-controller.md#getpaddingceil)
 - [setActive](https://phaser.io/oss/docs/api-documentation/class/filters-controller.md#setactive)
 - [setPaddingOverride](https://phaser.io/oss/docs/api-documentation/class/filters-controller.md#setpaddingoverride)




---

## Public Methods

### setAlpha

#### \<instance> setAlpha(alpha)


**Description:**

Sets the alpha value to use for the key. Alpha controls the opacity of pixels matched by the key color, in the range 0 to 1. This is stored in the fourth element of the color array. The RGB color values are preserved.

**Parameters:**
| name | type | optional | description |
| ---- | ---- | -------- | ----------- |
| alpha | number | No | The alpha value to set on the key texture, between 0 (fully transparent) and 1 (fully opaque). |


**Returns:** [Phaser.Filters.Key](https://phaser.io/oss/docs/api-documentation/class/filters-key.md) - This Filter Controller.


> Source: [src/filters/Key.js#L108](https://github.com/phaserjs/phaser/blob/v4.1.0/src/filters/Key.js#L108)  
Since: 4.0.0


---

### setColor

#### \<instance> setColor(color)


**Description:**

Sets the color to use for the key. This is stored in the first three elements of the color array. The alpha value is preserved.

**Parameters:**
| name | type | optional | description |
| ---- | ---- | -------- | ----------- |
| color | number \| string | Array.\<number> | [Phaser.Display.Color](https://phaser.io/oss/docs/api-documentation/namespace/display-color.md) | No | The color to use for the key. It can be a hexcode number or string, an array of 3 numbers between 0 and 1, or a Color object. |


**Returns:** [Phaser.Filters.Key](https://phaser.io/oss/docs/api-documentation/class/filters-key.md) - This Filter Controller.


> Source: [src/filters/Key.js#L125](https://github.com/phaserjs/phaser/blob/v4.1.0/src/filters/Key.js#L125)  
Since: 4.0.0


---

---

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Read any page of this site as Markdown by adding `.md` to its URL (the home page is https://phaser.io/index.md), or by asking for `text/markdown`. The index for agents is https://phaser.io/llms.txt. On the site's pages, the browser's Web MCP also offers `phaser_ae_guide`, `read_page_as_markdown` and `open_phaser_ae`.