FLIR® thermal cameras like the FLIR ONE® include both a thermal and a visual light camera. The latter is used to enhance the thermal image using an edge detector.

The resulting image is saved as a jpg image but both the original visual image and the raw thermal sensor data are embedded in the jpg metadata.

This small Python tool/library allows to extract the original photo and thermal sensor values converted to temperatures.

This tool relies on exiftool. It should be available in most Linux distributions (e.g. as perl-image-exiftool in Arch Linux or libimage-exiftool-perl in Debian and Ubuntu).

It also needs the Python packages numpy and matplotlib (the latter only if used interactively).

# sudo apt update
# sudo apt install exiftool
# sudo pip install numpy matplotlib

This module can be used by importing it:

import flir_image_extractor
fir = flir_image_extractor.FlirImageExtractor()
fir.process_image('examples/ax8.jpg')
fir.plot()

Or by calling it as a script:

python flir_image_extractor.py -p -i 'examples/zenmuse_xtr.jpg'

usage: flir_image_extractor.py [-h] -i INPUT [-p] [-exif EXIFTOOL]
                               [-csv EXTRACTCSV] [-d]

Extract and visualize Flir Image data

optional arguments:
  -h, --help            show this help message and exit
  -i INPUT, --input INPUT
                        Input image. Ex. img.jpg
  -p, --plot            Generate a plot using matplotlib
  -exif EXIFTOOL, --exiftool EXIFTOOL
                        Custom path to exiftool
  -csv EXTRACTCSV, --extractcsv EXTRACTCSV
                        Export the thermal data per pixel encoded as csv file
  -d, --debug           Set the debug flag

This command will show an interactive plot of the thermal image using matplotlib and create two image files flir_example_thermal.png and flir_example_rgb_image.jpg. Both are RGB images, the original temperature array is available using the get_thermal_np or export_thermal_to_csv functions.

The functions get_rgb_np and get_thermal_np yield numpy arrays and can be called from your own script after importing this lib.

• Flir One (thermal + RGB)
• Xenmuse XTR (thermal + thumbnail, set the subject distance to 1 meter)
• AX8 (thermal + RGB)

Other cameras might need some small tweaks (the embedded raw data can be in multiple image formats)

Raw value to temperature conversion is ported from this R package: https://github.com/gtatters/Thermimage/blob/master/R/raw2temp.R Original Python code from: https://github.com/Nervengift/read_thermal.py