I. Introduction
Environmental perception plays a vital role in the fields of autonomous driving [1], robotics [2], etc., and this perception influences the subsequent decisions and control of such devices [3]–[5]. Fog is a common form of weather, and when fog exists, the pixel values of foggy images are irregularly higher than those of clear images. As a result, the texture of foggy images is less than that of clear images. There are already many methods for semantic segmentation of clear images, which can extract and express the features of clear images and achieve good semantic segmentation results. However, the performance of these methods on foggy images is poor. This poor performance occurs because current methods cannot efficiently extract and express the features of foggy images. Moreover, foggy image data are not sparse, and the current excellent work [6], [7] on sparse data cannot be used. Therefore, to date, researchers have developed two ways to address this problem: