Flyr is a library for extracting thermal data from FLIR images written fully in Python, without depending on ExifTool.

Flyr

Flyr is a library for extracting thermal data from FLIR images written fully in Python, without depending on ExifTool.

Other solutions are wrappers around ExifTool to actually do the hard part of extracting the thermal data. Flyr is a reimplementation of the ExifTool's FLIR parser. Practically, this offers the following benefits:

• Faster decoding because no new process needs to be started and in-memory data does not need to be communicated to this other process
• More accurate, because Flyr uses all of the metadata to translate the raw values into Kelvin, while other projects have a certain set hardcoded. The differences are often about 0.1°C, but can be as high as 0.6°C.
• Easier and robust installation and deployment, because flyr is completely installable from PyPI.
• Arguably simpler use: no need to create a superfluous extraction object; simply call thermogram = flyr.unpack(flir_file_path) and done
• Extra features (see feature section) such as different units, built-in rendering and adjustable thermal data.

Installation

Flyr is installable from PyPi: pip install flyr.

Flyr depends on three external packages, all installable through pip: pip install numpy nptyping pillow. Pillow does the conversion from embedded images to numpy arrays, nptyping allows for high quality array type annotations. Numpy provides the n-dimensional arrays necessary to contain the thermal and optical data.

Usage and features

Different units

Thermal data is available in kelvin, celsius and fahrenheit.

import flyr

flir_path = "thermograms/flir_e5_2.jpg"
thermogram = flyr.unpack(flir_path)

thermal = thermogram.kelvin  # As kelvin
thermal = thermogram.celsius  # As celsius
thermal = thermogram.fahrenheit  # As fahrenheit


To read the embedded photo, access either optical or optical_pil to respectively get a 3D numpy or Pillow Image object with the photo.

import flyr

flir_path = "thermograms/flir_e5_2.jpg"
thermogram = flyr.unpack(flir_path)
img_arr = thermogram.optical  # Also works
thermogram.optical_pil.save("optical.jpg")


Built-in support for rendering

Flyr has built-in support to render thermal data to RGB images. It is possible to use different palettes and normalize by percentiles or absolute values.

import flyr

flir_path = "thermograms/flir_e5_2.jpg"
thermogram = flyr.unpack(flir_path)

palettes = ["turbo", "cividis", "inferno", "grayscale", "hot"]
for p in palettes:
# The below call returns a Pillow Image object.
# A sibling method called render returns a numpy array.
render = thermogram.render_pil(
min_v=27.1,
max_v=35.6,
unit="celsius",
mode="minmax",
palette=p,
)
render.save(f"render-{p}.png")


To render by percentiles, call as below. This approach is useful when it isn't know what temperature range to render.

thermogram.render_pil(
min_v=0.0,
max_v=1.0,
mode="percentilea",
palette="copper",
).save(f"render-percentiles.png")


It is possible to update the camera settings / parameters with which the thermal data is calculated. A typical value to adjust would be emissivity, but object_distance, relative_humidity and others are also configurable. See the parameters of FlyrThermogam.__raw_to_kelvin() for which.

import flyr

flir_path = "thermograms/flir_e5_2.jpg"
thermogram = flyr.unpack(flir_path)

emissivities = [0.6, 0.7, 0.8, 0.9, 1.0]
for e in emissivities:
# thermal = thermogram.celsius  # Access updated data as normal
render = thermogram.render_pil(
min_v=27.1,
max_v=35.6,
unit="celsius",
mode="minmax",
palette="viridis",
)
render.save(f"render-{e}.png")


Read from file, from file handle or binary stream

Call flyr.unpack on a filepath to receive a numpy array with the thermal data. Alternatively, first open the file in binary mode for reading and and pass the the file handle to flyr.unpack.

import flyr

# From file path
flir_path = "thermograms/flir_e5_2.jpg"
thermogram = flyr.unpack(flir_path)  # From file path

# From file handle / binary stream
with open(flir_path, "rb") as flir_handle:  # In binary mode!
thermogram = flyr.unpack(flir_handle)


Supported cameras

Currently this library has been tested to work with:

• FLIR E4
• FLIR E5
• FLIR E6
• FLIR E8
• FLIR E8XT
• FLIR E53
• FLIR P60 (PAL)
• FLIR E75
• FLIR T630SC
• FLIR T660

However, the library is still in an early phase and lacks robust handling of inconsistent files. When it encounters such an image it immediately gives up raising a ValueError, while it could also do a best effort attempt to extract anyway. This is planned.

Camera's that sometimes do and don't work:

• FLIR ThermaCAM P640
• FLIR ThermaCAM P660 West (more often doesn't than does)

Camera's found not to work (yet):

• FLIR E60BX
• FLIR ThermoCAM B400
• FLIR ThermaCAM SC640
• FLIR ThermaCam SC660 WES
• FLIR ThermaCAM T-400
• FLIR S60 NTSC
• FLIR SC620 Western
• FLIR T400 (Western)
• FLIR T640
• FLIR P660

Contributing

Pull requests are welcome. For major changes, please open an issue first to discuss what you would like to change. Most help is currently needed supporting more models and testing against more pictures. Testing and developing for your own camera's images or FLIR Tools' samples is recommended.

Acknowledgements

This code would not be possible without ExifTool's efforts to document the FLIR format. Previous work in Python must also be acknowledged for creating a workable solution.

Flyr is licensed under The European Union Public License 1.2. The English version is included in the license file. Translations for all EU languages, each fully legally valid, can be found at the EUPL website.

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