Bretina - Python Image Testing Framework

Bretina is a python package designed to support testing of the images.

Bretina is designed as an extension of the python unit test module. Provides set of assertions which can be used to verify correctness of the image.

In typical application, content of the device LCD display is captured with a camera and Bretina is used to verify correctness of the defined regions in the image - such as region color, presence of an icon, correctness of the text representation and other aspects.

Documentation

can be found on https://docs.benderrobotics.com/bretina (Not publicly available ATM).

Download and install latest release

Bretina can be downloaded from within the internal BR network by calling:

    $ pip install bretina

For optical character recognition Bretina offers two engines:

• Tesseract
• PaddleOCR

To change the OCR engine set the bretina.OCR_ENGINE to either OcrEngine.TESSERACT or OcrEngine.PADDLE. By default OcrEngine.TESSERACT is set.

PaddleOCR local models

By default PaddleOCR downloads its models from the internet on first use. To use models bundled locally instead, install the models extra. The bretina-models package is hosted on the Bender Robotics private PyPI, so it has to be passed as the extra index:

    $ pip install bretina[models] --extra-index-url https://pypi.benderrobotics.com

When the bretina-models package is available, PaddleOCR automatically uses the local models instead of downloading them.

Tesseract usage

To utilize Tesseract, it has to be installed as a standalone application and registered into system PATH. Installation files can be downloaded from https://github.com/tesseract-ocr/tesseract (tested with Tesseract version 5). Windows installer is provided by Mannheim University Library at https://github.com/UB-Mannheim/tesseract/wiki.

After the installation, add path to the tesseract.exe to your system PATH.

For the best OCR performance install the slower, but more accurate datasets tessdata_best (https://github.com/tesseract-ocr/tessdata_best). Extract the downloaded archive into the installation directory of the tesseract OCR.

This is an expected structure of the tesseract installation directory:

• C:\Program Files\Tesseract-OCR- tesseract installation
  • \tessdata - original tessdata dataset
    • afr.traineddata
    • ...
  • \tessdata_best - extracted best dataset
    • afr.traineddata
    • ...

Building Bretina from the source

If you want to build Bretina from the source, you need to clone the repository first. Then checkout to devel branch to get the latest version, or to feature/* branches for the cutting edge versions.

    $ git checkout devel

For building the python wheel, we use GNU make.

make expects that your pip3 installation will be available under pip command. Also there is a possibility that setup.py may fail on bdist_wheel as an not known argument. To fix this, install wheel package again.

Navigate to top-level directory of the cloned repository and you will be able to use the following commands:

    $ make install    # First time Bretina installation. It will build the source and install it using pip
    $ make reinstall  # Pulled new commit? Use this to build new wheel, uninstall and install the new version using pip
    $ make all        # Just builds the wheel
    $ make clean      # Cleans the build directories and files

Builded wheel is located in Bretina/dist/.

Installing make

On Ubuntu like machines execute the following command:

    $ sudo apt install make

If you are on windows machine, you can install a MinGW. In the MinGW installer choose mingw32-base-bin and msys-base-bin packages, then click on Installation and Apply changes. Don't forget to add the make binary to the system PATH. Default install location should be C:\MinGW\msys\1.0\bin\.