Constant time O(1) image fog removal using lowest level channel

In this reported work, the lowest level channel prior is proposed for image fog removal. The use of the lowest level channel is simplified from the dark channel prior. It is based on a key observation that fog-free intensity in a colour image is usually the minimum value of trichromatic channels. To estimate the transmission model, the dark channel prior then performs as a min filter for the lowest intensity. However, the min filter results in halo artefacts, specifically for neighbours of edge pixels. Instead of the min filter, this work utilises the exact O(1) bilateral filter to solve this problem. Experimental results show the high performance of the proposed method.