An improved nonuniformity correction algorithm is presented which is suitable for infrared focal plane arrays with a nonlinearity of the photoresponse characteristic. Compared to older algorithms, it is simpler, faster and easier to implement by software or hardware. At the same time, it is shown that the correction precision and the correction effect of the new algorithm are substantially the same as that of the old one through theoretical analysis and comparisons of simulation results. (C) 1998 Elsevier Science B.V.