Estimating Atmospheric Visibility Using General-Purpose Cameras

There is a growing interest in using general-purpose cameras to monitor a variety of physical phenomenon. In particular, a number of visibility camera networks have recently been deployed to complement traditional means for estimating atmospheric visibility. However, the images from these cameras have so far only been used to perform qualitative analysis. This work investigates image processing techniques for deriving quantitative measures of visibility from digital images in an automated fashion. Two methods are described, one which uses image contrast computed in the spatial domain and another which uses spectral energy computed in the frequency domain. Our quantitative measures are shown to correlate well with traditional measures of visibility from specialized equipment when evaluated using a ground-truth dataset from the Phoenix region.