Non-uniformity correction mitigating the effect of lens temperature

Abstract

Non-uniformity correction (NUC) is a standard procedure for infrared (IR) cameras. The effect of lens temperature, however, is often ignored during the implementation of a NUC. Ignoring the effect of temperature is acceptable if the lens temperature is at much lower than ambient temperature, whose irradiance onto the focal plane array (FPA) is much less than that of the scene. Ignoring the effect of temperature is also acceptable if the lens temperature during the calibration for NUC is the same as that during the scene collection. The change of the lens temperature in between the calibration for NUC and the scene collection, however, affects the performance. Such degradation in image quality is presented by the frames taken by a mid-wave infrared (MWIR) camera. An empirical law is established to mitigate the effect of lens temperature, which offers various options for NUC. As an example, we propose a four-point NUC that mitigates the effect of the lens temperature. We demonstrate its usefulness by applying it to the frames taken at various lens temperatures. The results are satisfactory.