Thick Cloud Removal in Optical Remote Sensing Images Using a Texture Complexity Guided Self-Paced Learning Method

Thick clouds seriously impact the quality of optical remote sensing images (RSIs) and limit their application. For removing the cloud, some learning-based methods have been proposed and attracted considerable attention. However, these methods need to train paired multitemporal images with/without cloud, which are difficult and costly to collect. To solve this problem, we propose a novel texture complexity-guided self-paced learning (SPL) framework to remove the thick cloud from single RSIs. The framework does not need paired images and it exploits a texture complexity-guided mechanism to rank the self-generated cloud-corrupted training samples by texture complexity from low to high and then trains the generative adversarial cloud removal network using the SPL technique. In this way, the cloud removal network learns to restore the cloud-corrupted areas from easy to hard and thus to realize the image reconstruction for different difficulty levels. In addition, we introduce a structural similarity (SSIM) loss function to optimize the training network and improve the coherence of the image structure. Simulated and real experiments are performed on the single images acquired by Gao Fen-1 (GF-1) and Sentinel-2 satellites to validate the effectiveness of the proposed method. The results show that the proposed method has a better performance in cloud removal than other state-of-the-art methods, especially for the images of the areas with complex textures. The source codes are available at https://github.com/GeoX-Lab/TPL.