In this paper we introduce a novel approach to restore a
single image degraded by atmospheric phenomena such as fog or haze.
The presented algorithm allows for fast identification of hazy regions
of an image, without making use of expensive optimization and refinement
procedures. By applying a single per pixel operation on the original
image, we produce a ’semi-inverse’ of the image. Based on the hue disparity
between the original image and its semi-inverse, we are then able
to identify hazy regions on a per pixel basis. This enables for a simple
estimation of the airlight constant and the transmission map. Our approach
is based on an extensive study on a large data set of images,
and validated based on a metric that measures the contrast but also
the structural changes. The algorithm is straightforward and performs
faster than existing strategies while yielding comparative and even better
results. We also provide a comparative evaluation against other recent
single image dehazing methods, demonstrating the efficiency and utility
of our approach.