A .csq file is the radiometric video format written by FLIR thermal cameras. Every frame keeps the raw reading of every sensor pixel, which is what makes it possible to ask what temperature something was long after the recording was made.
A CSQ is a stream of FFF records laid end to end — one per frame, each a small header followed by the frame itself. The image is stored as 16-bit values in JPEG-LS, which is lossless, so nothing about the measurement is thrown away to save space.
Those 16-bit numbers are not temperatures. They are raw sensor counts, and turning one into a temperature needs the calibration constants the camera wrote into the same file — the Planck curve for the detector, along with the emissivity, reflected apparent temperature, distance and humidity that were set when the recording was made. Change the emissivity afterwards and every temperature in the recording changes with it, which is exactly why the raw counts are what gets stored.
| Format | Holds temperatures | What it is |
|---|---|---|
| .csq | Yes | Radiometric recording, frames compressed losslessly |
| .seq | Yes | The same recording with frames left uncompressed — much larger |
| Radiometric JPEG | Yes | A single still, with the thermal data embedded alongside a visual image |
| .mp4 / .avi | No | Eight-bit colour, exported for viewing — the measurement is gone |
The practical difference between CSQ and SEQ is size. Both carry the same frames; CSQ compresses them and SEQ does not, so the same capture can be several times larger as a SEQ.
FLIR's own software reads these files — Thermal Studio, Research Studio and the older FLIR Tools — but all of them are Windows desktop products, and the versions that export video are paid.
You do not need any of them to look at a recording. Drop a .csq file onto this site and it opens in the browser: point at any pixel to read its temperature, step or scrub through the frames, switch between thermal palettes, and export what you need as MP4, PNG or a JSON array of temperatures. The file is deleted from the server automatically once it has gone a day without being opened.
A CSQ file is the radiometric video format written by FLIR thermal cameras. It stores a sequence of frames, each holding the raw 16-bit sensor reading for every pixel together with the calibration constants needed to convert those readings to temperatures.
Both are FLIR recording formats holding the same kind of radiometric frames. CSQ is the compressed variant, storing each frame as JPEG-LS, while SEQ stores frames uncompressed. CSQ files are therefore much smaller for the same recording.
Yes. CSQ Viewer opens a .csq recording in the browser and reads per-pixel temperatures without FLIR Tools, Thermal Studio or ResearchIR. Command-line options such as exiftool with ffmpeg, and the Python and R libraries that build on them, also work.
A CSQ keeps the raw sensor reading for every pixel of every frame rather than an eight-bit colour image, because that is what makes a temperature measurement possible afterwards. A thermal JPEG only preserves how the scene was coloured at capture time.
If you need help working with .CSQ files or thermal images and videos in general, feel free to contact me.