Detection of skin lesions using diffuse polarisation

This paper describes the use of polarisation information for surface inspection. We consider the problem of detecting regions of damage and disease in the skins of different types of fruit and vegetable. We commence by using moments to estimate the components of the polarisation image (mean-intensity, polarisation and phase) from images obtained with multiple polariser angles. Using the polarisation information and the Fresnel theory, we develop a characterisation of the surface reflectance based on spherical harmonic coefficients. We use the normalised cut method to segment surfaces into different regions depending on their surface reflectance properties. Experiments on samples of bruised fruit illustrate the practical utility of the method.