Departmental Papers (ESE)


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.

Document Type

Journal Article

Date of this Version

August 2006


Copyright 2006 Optical Society of America, Inc. Postprint version. Published in Optics Express, Volume 14, Issue 16, August 2006, pages 7099-7108.

(The manuscript can be found at



Date Posted: 18 July 2007

This document has been peer reviewed.