Thermal fundamentals

Radiometric thermal files: how to check a camera before buying

A practical sample-file test for inspection teams: distinguish thermal video, temperature overlays and radiometric data your reporting software can reanalyse.

The key point

Before buying a camera for temperature reports, open an original sample file in your intended software and measure a point that was not selected during capture. A temperature label burned into a video cannot pass that test.

Which output does your client actually need?

If a client asks for a thermal inspection report, clarify whether they need evidence of a suspected anomaly or temperature data they can reanalyse. Both may be called a thermal image, but the purchasing requirements are different.

Thermal outputs and what they retain
OutputWhat you can do laterWhat it does not establish
Colour thermal image or videoReview the visual pattern and annotate the observed locationA temperature value for every pixel
Image with a temperature overlayRead the values that were displayed during captureChoose a new measurement point or change the original settings
Radiometric image with supported metadataUse compatible software to analyse retained measurement dataUniversal compatibility or accurate temperatures under every condition
Radiometric stream or sequenceAnalyse measurement data over time if this format is supportedThat a normal MP4 recording retains the same data

Run this sample-file acceptance test

Request an original capture from the exact configuration being quoted, the software name and version, the file-format documentation and any licence needed to analyse it. Ask for both a visible reference and the thermal original. A screenshot pasted into a sales presentation is not a suitable test file.

  • Open the original on the workstation and software your analyst will use. Record the software version and any import or licence requirement.
  • Select several locations that were not marked at capture. Confirm the software reads retained measurement data rather than displaying an existing text label.
  • Check whether supported settings such as emissivity or reflected temperature can be inspected and, when required, adjusted. Record which settings are fixed.
  • Export the report you must deliver. Confirm that the asset identifier, capture time, units and images remain associated.
  • If live data or a sequence is required, repeat with that output. Passing a still-image test does not demonstrate radiometric video.

Treat the result as pass, conditional or fail

Use the table below in a purchase evaluation. A file that fails the reporting requirement might still be useful for live observation; it is simply a different purchase.

A sample-file decision record
Observed resultPurchase implicationNext action
File opens; new points and required settings workCandidate meets this part of the reporting workflowAttach the original, software version and report to acceptance evidence
File opens only in supplier softwareWorkflow depends on that softwareConfirm licences, supported operating systems, export and long-term access
Image opens but only existing labels can be readNo demonstrated reanalysis capabilityRequest a documented radiometric original or choose a visual-only use case
Proprietary file cannot be openedReporting path remains unresolvedResolve it before accepting a measurement-data requirement

Why a readable temperature can still be misleading

An infrared camera receives radiation from the viewed surface and surroundings. Its temperature estimate depends on the measurement model and settings. Shiny surfaces can reflect warmer objects; small targets can be mixed with cooler background within a measurement area. Moving farther away can therefore change the reported result even when the asset has not changed.

Thermal sensitivity, often given as NETD in mK, concerns the ability to distinguish small differences under specified conditions. It is not the same as absolute temperature accuracy. Ask for the quoted model’s accuracy conditions and a procedure appropriate to your asset; do not convert a sensitivity value into an accuracy promise.

What our catalog can and cannot establish

The compact multi-sensor and 48 MP configurations list spot and area temperature measurement. The lightweight configuration does not specify temperature measurement. Available documentation does not establish per-pixel temperature-file export for any of the three.

If reanalysis is mandatory, keep the shortlist provisional until the sample-file test passes. A 640 × 512 detector, Ethernet output or on-screen measurement function is insufficient evidence on its own.

Copy this requirement into the quote

Required deliverable: an original thermal file from the quoted configuration that opens in our named software, allows new measurement locations to be selected and retains the metadata needed for our report. Please identify file format, software version, licence costs and any settings that cannot be adjusted after capture.

Acceptance will use a supplied original file and an exported report produced on our workstation. If only still images are supported, state that explicitly. Any requirement for live radiometric data or sequences must be demonstrated separately.

Sources & further reading

Match the payload to your requirements.

Compare documented specifications, then confirm the details of your integration.

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