Refractive index estimation using photometric stereo

In this paper we consider the problem of computing refractive index using polarisation information considering that the refractive index varies with the change in surface information for fruits and vegetables. We proceed by using the method of moments to estimate the components of the polarisation image (mean-intensity, polarisation and phase) from intensity images obtained using multiple polariser angles. We use the polarisation information, photometric stereo and the Fresnel theory, for estimating the refractive index. We use the photometric stereo to compute the surface normals for estimation of angles. Experiments on fruits at different stages of decay illustrate the practicality of the method.