How does FLIR calibrate thermal cameras? What is NUC?

FLIR's Boson, Tau2, and Quark2 thermal imaging cameras are factory-calibrated to generate non-uniformity compensation (NUC) coefficients which are applied automatically by the camera in real time to maintain good image quality. The coefficients comprise a NUC table and are typically valid for a specific subset of the total operating temperature range. Consequently, there are multiple NUC tables to span the full operating temperature range, and the camera automatically selects the optimum table based on its temperature.

Note that Lepton only has a single NUC table, so automatic table changing is not applicable.