Effective Local Airlight Estimation for Image Dehazing

This paper introduces an effective strategy to enhance the visibility of hazy images, especially those obtained in night-time conditions. Compared to day-time, in night-time scenes, the lighting generally arises from multiple artificial sources and therefore may be considered intrinsically as being non-uniform. As a result, conventional global atmospheric light (airlight) estimation strategies become irrelevant. In this work, we propose a simple yet effective patch-based atmospheric light estimation. To circumvent the problem of selecting an appropriate patch size, we propose to estimate the atmospheric light on several patch sizes, and to define the local airlight as the average of those estimates. An extensive experimental validation demonstrates that the proposed strategy is able to recover the scene radiance without unwanted color-shifting, and proves that our approach is competitive compared to recent techniques in terms of restored image quality.