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