flirextractor

An efficient GPLv3-licensed Python package for extracting temperature data from FLIR IRT images.

Differences from existing libraries

There is an existing Python package for extracting temperature values from raw IRT images, see nationaldronesau/FlirImageExtractor. However, it has some issues that I didn't like:

• Most importantly, it is forked from the UNLICENSED Nervengift/read_thermal.py, so until Nervengift/read_thermal.py#4 is answered, this package cannot be legally used.
• Secondly, it is quite inefficient, as it runs a new exiftool process for each image, and it converts the temperature for each pixel, instead of using numpy's vectorized math.

Installing

You can install flirextractor from pip.

pip3 install flirextractor

Or, using the python package manger poetry (recommended):

poetry add flirextractor

Make sure you install exiftool as well.

On RHEL, this can be installed via:

sudo yum install perl-Image-ExifTool

On Debian, this can be installed via:

sudo apt update && sudo apt install libimage-exiftool-perl -y

Usage

Each FLIR infrared image is loaded in Celsius as a 2-dimensional numpy.ndarray.

To load data from a single FLIR file, run:

from flirextractor import FlirExtractor
with FlirExtractor() as extractor:
    thermal_data = extractor.get_thermal("path/to/FLIRimage.jpg")

Data can also be loaded from multiple FLIR files at once in batch mode, which is slightly more efficient:

from flirextractor import FlirExtractor
with FlirExtractor() as extractor:
    list_of_thermal_data = extractor.get_thermal_batch(
        ["path/to/FLIRimage.jpg", "path/to/another/FLIRimage.jpg"])

Once you have the numpy.ndarray, you can export the data as a csv with:

import numpy as np
np.savetxt("output.csv", thermal_data, delimiter=",")

You can display the image for debugging by doing:

from PIL import Image
thermal_image = Image.fromarray(thermal_data)
thermal_image.show()

See ./scripts/example.py for more example usage.

Testing

Use the Python package manager poetry to install test dependencies:

poetry install

Then run pytest to run tests.

poetry run pytest

You can run linters with pre-commit:

poetry run pre-commit run --all-files

Acknowledgements

This work was supported by the Engineering and Physical Sciences Research Council [Doctoral Training Partnership Grant EP/R513325/1].

Additionally, many thanks to Glenn J. Tattersall, for their gtatters/Thermimage R package. This work uses an image and adapts part of gtatters/Thermimage under the GPLv3.0 License.