> For the complete documentation index, see [llms.txt](https://docs.auterion.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.auterion.com/~/changes/TDRfjBXXgHmxK48cWqay/app-development/resources/skynode-vision-kit-s/install-and-test-a-simple-vision-app.md).

# Install and test a simple vision app

This example app uses the vision kit API to compute the average brightness of each frame captured by the camera.

## Verify your development environment

Before proceeding, ensure that you have successfully set up your development environment.

{% content-ref url="/pages/VCu3tneKh1CEejgtB6Sp" %}
[Development environment Setup](/~/changes/TDRfjBXXgHmxK48cWqay/app-development/app-development/application-development.md)
{% endcontent-ref %}

It is also recommended that you be familiar with the app development workflow.

{% content-ref url="/pages/FuAv9g84iWZKBc6BAK0p" %}
[Application Development](/~/changes/TDRfjBXXgHmxK48cWqay/app-development/app-development/application-development-1.md)
{% endcontent-ref %}

## Download the source code

In order to get access to the application's source code, you need to be part of the Auterion Developer program. If this is not the case follow [these instructions](/~/changes/TDRfjBXXgHmxK48cWqay/app-development/app-development.md) to quickly get you registered.

The code for the vision kit example app is part of a downloadable bundle called "App examples", which is published inside the [Developer section](https://suite.auterion.com/developer/skynode) of Auterion Suite.

{% hint style="warning" %}
The vision kit example is available starting from App Examples - v3.
{% endhint %}

Download the folder and extract the vision kit example to your PC.

## Build and install the app

In the root directory of the example, run the following commands to build and subsequently install the app on your device:

```bash
auterion-cli app build
auterion-cli app install
```

The app `com.auterion.vision-kit-example` should now be listed in the installed apps section. You can verify that via WebUI or via the `auterion-cli app list` command.

## App functionality

The app runs a ROS2 node which performs the following steps:

1. Subscribe to image messages on the `/camera/image_raw` ROS2 topic.
2. For each YUV422-encoded image received, compute the average brightness (Y) component of all pixels in the image.
3. Publish the result on the `/image_statistics/average_brightness` ROS2 topic.

## Inspect the output

Connect to Skynode via SSH and source ROS2. You can then observe the computed average brightness component on the topic configured in the app:

```bash
pc> ssh root@10.41.1.1    #SSH into Skynode

host> docker ps     #Copy the container ID for the desired app
host> docker exec -ti <container-id> /bin/bash

app> source /opt/ros/humble/setup.bash
app> ros2 topic echo /image_statistics/average_brightness
```