Instant dehazing of images using polarization

We present an approach to easily remove the effects of haze from images. It is based on the fact that usually airlight scattered by atmospheric particles is partially polarized. Polarization filtering alone cannot remove the haze effects, except in restricted situations. Our method, however, works under a wide range of atmospheric and viewing conditions. We analyze the image formation process, taking into account polarization effects of atmospheric scattering. We then invert the process to enable the removal of haze from images. The method can be used with as few as two images taken through a polarizer at different orientations. This method works instantly, without relying on changes of weather conditions. We present experimental results of complete dehazing in far from ideal conditions for polarization filtering. We obtain a great improvement of scene contrast and correction of color. As a by product, the method also yields a range (depth) map of the scene, and information about properties of the atmospheric particles.

1. Introduction

Recently there has been a growing interest in the analysis of images of scenes affected by weather phenomena. The main objective has been to enhance [6], [10], [15], [24] images taken in poor visibility, and even restore the clear-day visibility of the scene [11], [12], [14]. It has also been observed that degradation of images by atmospheric scattering can actually be exploited to obtain information about the scene, particularly its range map [4], [12], [4]. Some image enhancement methods proposed in the past require prior information about the scene (e.g., distances [15], [24]). Other methods are based on specialized radiation sources and detection hardware [16],[23].