Generalized algebraic algorithm for scene-based nonuniformity correction

This paper presents an overview of three recently developed scene-based nonuniformity correction techniques, namely, the algebraic scene-based algorithm (ASBA), the extended radiometrically accurate scene-based algorithm (RASBA) and the generalized algebraic scene-based algorithm (GASBA). The ASBA uses pairs of image frames that exhibit one-dimension sub-pixel motion to algebraically extract estimates of bias nonuniformity. The RASBA incorporates arbitrary sub- and super-pixel two-dimensional motion in conjunction with limited perimeter-only absolute calibration to obtain radiometrically accurate estimates of the bias nonuniformity. The RASBA provides the advantage of being able to maintain radiometry in the interior photodetectors without interrupting their operation. The GASBA is a generalized non-radiometric form of the algorithm that uses image pairs with arbitrary two-dimensional motion and encompasses both the ASBA and RASBA algorithms. This generalization is accomplished by initially guaranteeing bias uniformity in the perimeter detectors. This uniformity can be achieved by first applying the ASBA estimates. The generalized algorithm is then able to automatically maintain perimeter uniformity without the need for re-application of the ASBA. Thus, the GASBA is able to operate completely in a non-radiometric mode, alleviating the need for the perimeter calibration system if desired. The generalized algorithm is applied to real infrared imagery obtained from both cooled and uncooled infrared cameras. A hardware implementation of the proposed algorithm will also be discussed along with several ongoing commercial applications of the technology.