I. Introduction
Transmission lines are widely used in the industrial field and daily life in modem society. They are mainly composed of cables, insulators and other components. However, these basic components are often subject to wear and corrosion in the outdoor environment, resulting in unexpected interruption of power supply and even serious casualties. Therefore, visual inspection is often used as a method of regular inspection and predictive maintenance to ensure the reliability of transmission lines [1]–[3]. As the most commonly used power line visual inspection method, UAV patrol inspection can not only meet the requirements of UAV route planning, but also be used in the field of visual inspection and detection [4]. However, due to bad weather, inspection time, shooting angles and other reasons, the illumination condition of the original data acquired by UAVs is irregular.