A method and apparatus for real-time polarization difference imaging (PDI) video including an imaging lens focusing the light on to a collimating lens, whereby the stimulus beams becomes parallel before striking a polarizing beam-splitter. Segregated orthogonally polarized components of the stimulus are then focused on imaging sensors, and one sensor's output signal is subtracted from the other, thereby creating a real-time polarization difference video image. The efficiency of such a system is greatly enhanced by illuminating the target with a polarized light source (with a polarization orientation matching one of those used in the PDI process), and PDI-enhanced targets can be constructed with surface features and textures optimised to result in a maximum return signal strength and spatial contrast.