title: Separation and contrast enhancement of overlapping cast shadow components using polarization.
abstract: Shadow is an inseparable aspect of all natural scenes. When there are multiple light sources or multiple reflections several different shadows may overlap at the same location and create complicated patterns. Shadows are a potentially good source of information about a scene if the shadow regions can be properly identified and segmented. However, shadow region identification and segmentation is a difficult task and improperly identified shadows often interfere with machine vision tasks like object recognition and tracking. We propose here a new shadow separation and contrast enhancement method based on the polarization of light. Polarization information of the scene captured by our polarization-sensitive camera is shown to separate shadows from different light sources effectively. Such shadow separation is almost impossible to realize with conventional, polarization-insensitive imaging.
authors.affiliation: Electrical and Systems Engineering Department, University of Pennsylvania, 220 South 33rd Street Moore 203, Philadelphia, PA 19104-6390, USA. shschon@seas.upenn.edu
authors.forename: Shih-Schön
authors.initials: SS
authors.lastname: Lin
authors.forename: Konstantin M
authors.initials: KM
authors.lastname: Yemelyanov
authors.forename: Edward N
authors.initials: EN
authors.lastname: Pugh
authors.forename: Nader
authors.initials: N
authors.lastname: Engheta
mesh_terms: D003118:Color Perception; D003867:Depth Perception; D006801:Humans; D008029:Lighting; D009039:Motion Perception; D009903:Optical Illusions