home-assistant.io/source/_components/image_processing.seven_segments.markdown
2017-05-23 16:29:27 -07:00

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---
layout: page
title: "Seven segments display"
description: "Instructions how to use OCR for seven segemnts displays into Home Assistant."
date: 2017-05-18 08:00
sidebar: true
comments: false
sharing: true
footer: true
logo: home-assistant.png
ha_category: Image Processing
featured: false
ha_release: 0.45
og_image: /images/screenshots/ssocr.png
---
The `seven_segments` image processing platform allows you to read physical seven segments displays through Home Assistant. [`ssocr`](https://www.unix-ag.uni-kl.de/~auerswal/ssocr/) is used to extract the value shown on the display which is observed by a [camera](/components/camera/). `ssocr` need to be available on your system. Check the installation instruction for Fedora below or use `$ sudo apt-get install ssocr` on a Debian-based system:
```bash
$ sudo dnf -y install imlib2-devel
$ git clone https://github.com/auerswal/ssocr.git
$ cd ssocr
$ make
$ sudo make PREFIX=/usr install
```
To enable the OCR of a seven segement display in your installation, add the following to your `configuration.yaml` file:
```yaml
# Example configuration.yaml entry
image_processing:
- platform: seven_segments
source:
- entity_id: camera.seven_segments
```
Configuration variables:
- **ssocr_bin** (*Optional*): The command line tool `ssocr`. Set it if you use a different name for the executable. Defaults to `ssocr`.
- **x_position** (*Optional*): X coordinate of the upper left corner of the area to crop. Defaults to `0`.
- **y_position** (*Optional*): Y coordinate of the upper left corner of the area to crop. Defaults to `0`.
- **height** (*Optional*): Height of the area to crop. Defaults to `0`.
- **width** (*Optional*): Width of the area to crop. Defaults to `0`.
- **threshold** (*Optional*): Threshold for the difference between the digits and the background. Defaults to `0`.
- **digits** (*Optional*): Number of digits in the display. Defaults to `-1`.
- **source** array (*Required*): List of image sources.
- **entity_id** (*Required*): A camera entity id to get picture from.
- **name** (*Optional*): This parameter allows you to override the name of your `image_processing` entity.
### {% linkable_title Setup process %}
It's suggested that the first attempt to determine the needed parameters is using `ssocr` directly. This may require a couple of iterations to get the result
```bash
$ ssocr -D erosion crop 390 250 490 280 -t 20 -d 4 ss-test.jpg
```
This would lead to the following entry for the `configuration.yaml` file:
```yaml
camera:
- platform: local_file
file_path: /home/fab/.homeassistant/seven-seg.png
name: seven_segments
image_processing:
- platform: seven_segments
x_position: 390
y_position: 250
height: 280
width: 490
threshold: 20
digits: 4
source:
- entity_id: camera.seven_segments
```
<p class='img'>
<img src='{{site_root}}/images/screenshots/ssocr.png' />
</p>
With the help of a [template sensor](/components/sensor.template/), the value can be shown as badge.
```yaml
sensor:
- platform: template
sensors:
power_meter:
value_template: '{{ states.image_processing.sevensegement_ocr_seven_segments.state }}'
friendly_name: 'Ampere'
unit_of_measurement: 'A'
```