Single Image Haze Removal via Region Detection Network

Abstract

Haze removal typically works on a physical model to estimate how light is transmitted and lost due to absorption and scattering through the atmosphere. In this paper, a region detection network is proposed to learn the relationship between the hazy image and the medium transmission map in a patchwise manner; the transmission map is then used to remove haze via an atmospheric scattering model and enhance the detail of de-hazed images. To this end, we design a simple yet powerful deep convolutional neural network, which mainly consists of two types of network units and can be trained in an end-to-end manner. One network unit is a module with the residual structure that facilitates the learning process of the deep network. The other is a novel module with a cascaded cross channel pool, which fuses multi-level haze-relevant features and boosts the abstraction ability of the model on a nonlinear manifold. Moreover, an evolutionary-based enhancement method is developed to improve the level of detail of over-smoothed results. Several comparative experiments have been conducted on synthetic and real images, through which we conclude that the proposed method achieves state-of-the-art haze removal results, qualitatively and quantitatively. Supplementary experiments further indicate that our method works better against other adverse effects on vision quality (e.g., the mist formed by heavy rain and the veil met underwater). Moreover, we present a lightweight version of the proposed network, which achieves an impressive haze removal performance even on low-power devices.