Flir Image Extractor

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.

Requirements

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

Usage

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.

Supported/Tested cameras:

• 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)

Credits

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