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

Sharpness of the output image.

The `sharpen` parameter increases the definition of the edges of objects in an image.

## Syntax

```text
sharpen=a{a},r{r},t{t}
```

## Sub-parameters

| Param | Units     | Description                                       |
| ----- | --------- | ------------------------------------------------- |
| `a`   | `Number`  | Amount - Decimal number between `0` and `10`.     |
| `r`   | `Number`  | Radius - Decimal number between `0.5` and `1000`. |
| `t`   | `Integer` | Threshold -  whole number between `0` and `255`.  |

## Notes

1. The sharpen parameter is an implementation of an unsharp mask.

## Examples

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

| Example usage                                                           | Description                                                                |
| ----------------------------------------------------------------------- | -------------------------------------------------------------------------- |
| [`?sharpen=a5,r2,t1`](https://www.fastly.io/image.jpg?sharpen=a5,r2,t1) | Increase the sharpness of the image by amount:5, radius:2, and threshold:1 |