---
title: brightness
summary: null
url: https://www.fastly.com/documentation/reference/io/brightness
---

The `brightness` parameter increases or decreases the amount of perceived light an image radiates or reflects.

## Syntax

```text
brightness={value}
```

`value` may be any number between -100 and 100.

## Notes

1. The default value is `0`. This leaves the image unchanged.
2. A value of `100` will result in a fully white image.
3. A value of `-100` will result in a fully black image.

## Examples

Click the links to view the transformed image using a demo Fastly IO service.

| Example usage                                                     | Description               |
| ----------------------------------------------------------------- | ------------------------- |
| [`?brightness=50`](https://www.fastly.io/image.jpg?brightness=50) | Increase brightness by 50 |