---
part: pixi/examples
title: Opencv example
description: How to run opencv using pixi
---

The `opencv` example is located in the pixi repository.

```shell
git clone https://github.com/prefix-dev/pixi.git
```

Move to the example folder

```shell
cd pixi/examples/opencv
```

## Face detection

Run the `start` command to start the face detection algorithm.

```shell
pixi run start
```

The screen that starts should look like this:
![](https://storage.googleapis.com/prefix-cms-images/docs/opencv_face_recognition.png)

Check out the `webcame_capture.py` to see how we detect a face.

## Camera Calibration

Next to face recognition, a camera calibration example is also included.

You'll need a checkerboard for this to work.
Print this: [![chessboard](https://github.com/opencv/opencv/blob/4.x/doc/pattern.png?raw=true)](https://github.com/opencv/opencv/blob/4.x/doc/pattern.png)

Then run

```shell
pixi run calibrate
```

To make a picture for calibration press `SPACE`
Do this approximately 10 times with the chessboard in view of the camera

After that press `ESC` which will start the calibration.

When the calibration is done, the camera will be used again to find the distance to the checkerboard.

![](https://storage.googleapis.com/prefix-cms-images/docs/calibration_board_detected.png)