Robust Computation of the Polarisation Image

In this paper we show how to render the computation of polarisation information from multiple polariser angle images robust. We make two contributions. First, we show how to use M-estimators to make robust moments estimates of the mean intensity, polarisation and phase. Second, we show how directional statistics can be used to smooth the phase-angle, and to improve its estimation when the polarisation is small. We apply the resulting techniques to polariser images and perform surface quality inspection. Compared to polarisation information delivered by the three-point method, our estimates reveal finer surface detail.