Non-uniformity correction (NUC) adjusts for the tiny detector drift that occurs when the scene and environment change. In general, the thermal camera's own heat interferes with its temperature readings, and to improve accuracy, the thermal camera measures the infrared radiation of its own optics and then adjusts the image based on these readings. NUC adjusts the gain and offset for each pixel, producing higher quality, more accurate images.

During the NUC process, the thermal camera shutter falls between the optics and the detector, making a clicking sound that instantly freezes the image stream. The shutter acts as a planar reference source for the detector to calibrate itself and for thermal stabilization.

This happens often in uncooled infrared thermal cameras, but occasionally in cooled infrared thermal cameras, it is also known as FFC (Flat field correction).

During initial startup, the thermal camera performs NUC frequently. As thermal cameras heat up and reach a stable operating temperature, NUC will become less frequent. While you can get a thermal image about 20 seconds after turning it on, most thermal cameras require a warm-up time of at least 20 minutes in a stable environment with optimal temperature measurement accuracy.

A thermal imager will automatically perform a NUC, but you can also manually use the NUC function before taking important temperature measurements or taking critical images. This will help ensure optimal accuracy.