  This paper proposes a scheme for single image haze removal based on the
airlight field (ALF) estimation. Conventional image dehazing methods which are
based on a physical model generally take the global atmospheric light as a
constant. However, the constant-airlight assumption may be unsuitable for
images with large sky regions, which causes unacceptable brightness imbalance
and color distortion in recovery images. This paper models the atmospheric
light as a field function, and presents a maximum a-priori (MAP) method for
jointly estimating the airlight field, the transmission rate and the haze free
image. We also introduce a valid haze-level prior for effective estimate of
transmission. Evaluation on real world images shows that the proposed approach
outperforms existing methods in single image dehazing, especially when the
large sky region is included.
