Solar Image Cloud Removal based on Improved Pix2Pix Network

Abstract

In ground-based observations of the Sun, solar images are often affected by appearance of thin clouds, which contaminate the images and affect the scientific results from data analysis. In this paper, the improved Pixel to Pixel Network (Pix2Pix) network is used to convert polluted images to clear images to remove the cloud shadow in the solar images. By adding attention module to the model, the hidden layer of Pix2Pix model can infer the attention map of the input feature vector according to the input feature vector. And then, the attention map is multiplied by the input feature map to give different weights to the hidden features in the feature map, adaptively refine the input feature map to make the model pay attention to important feature information and achieve better recovery effect. In order to further enhance the model’s ability to recover detailed features, perceptual loss is added to the loss function. The model was tested on the full disk H-alpha images datasets provided by Huairou Solar Observing Station, National Astronomical Observatories. The experimental results show that the model can effectively remove the influence of thin clouds on the picture and restore the details of solar activity. The peak signal-to-noise ratio (PSNR) reaches 27.3012 and the learned perceptual image patch similarity (LPIPS) reaches 0.330, which is superior to the existed dehaze algorithms.