We first derive a formula that can successfully describe the device nonlinearity between the IR incidence corresponding to the blackbody temperature T and the pixel output V for infrared detectors such as QWIPs or QDIPs, which have a peak (not cutoff) type photo response.

Second, using this formula, we show that, in theory, conventional "two-point correction" can completely correct the non-uniformity; therefore, in the case of QWIP- or QDIP-FPA, the origin of the NUC incompleteness, that is, the origin of the residual non-uniformity in an IR image, is the nonlinear input-output characteristics in the electronics.

Last, we show that the nonlinearity in the electronics can be corrected by using our formula to reconstruct an almost completely non-uniformity corrected IR image.