Night images suffer not only from low light, but also from uneven
distributions of light. Most existing night visibility enhancement methods
focus mainly on enhancing low-light regions. This inevitably leads to over
enhancement and saturation in bright regions, such as those regions affected by
light effects (glare, floodlight, etc). To address this problem, we need to
suppress the light effects in bright regions while, at the same time, boosting
the intensity of dark regions. With this idea in mind, we introduce an
unsupervised method that integrates a layer decomposition network and a
light-effects suppression network. Given a single night image as input, our
decomposition network learns to decompose shading, reflectance and
light-effects layers, guided by unsupervised layer-specific prior losses. Our
light-effects suppression network further suppresses the light effects and, at
the same time, enhances the illumination in dark regions. This light-effects
suppression network exploits the estimated light-effects layer as the guidance
to focus on the light-effects regions. To recover the background details and
reduce hallucination/artefacts, we propose structure and high-frequency
consistency losses. Our quantitative and qualitative evaluations on real images
show that our method outperforms state-of-the-art methods in suppressing night
light effects and boosting the intensity of dark regions.

该论文提出了一种无监督的方法，通过层分解网络和光效抑制网络集成来来压制夜间图像中光效，并增强暗区域的照度

无监督夜间图像增强：层分解与光效抑制的结合

Unsupervised Night Image Enhancement: When Layer Decomposition Meets  Light-Effects Suppression

This paper provides a comprehensive survey of methods dealing with visibility
enhancement of images taken in hazy or foggy scenes. The survey begins with
discussing the optical models of atmospheric scattering media and image
formation. This is followed by a survey of existing methods, which are grouped
to multiple image methods, polarizing filters based methods, methods with known
depth, and single-image methods. We also provide a benchmark of a number of
well known single-image methods, based on a recent dataset provided by Fattal
and our newly generated scattering media dataset that contains ground truth
images for quantitative evaluation. To our knowledge, this is the first
benchmark using numerical metrics to evaluate dehazing techniques. This
benchmark allows us to objectively compare the results of existing methods and
to better identify the strengths and limitations of each method.

本文对处理模糊图像的能见度增强方法进行了全面的调查，提供了一个基于定量评估的排名以比较现有方法的结果，并为各种方法的优缺点提供了更好的认识。