If you’re wondering why your thermal image sometimes freezes and the camera makes a clicking noise, there’s no need to be alarmed, it’s performing a non-uniformity correction. Why does it do this?
Non-uniformity correction (NUC) adjusts for minor detector drift that occurs as the scene and environment change. Basically, the camera's own heat can interfere with its temperature readings. To improve accuracy, the camera measures the IR radiation from its own optics and then adjusts the image based on those readings. NUC adjusts gain and offset for each pixel, producing a higher quality, more accurate image.