Syn2Real Transfer Learning for Image Deraining Using Gaussian Processes

Recent CNN-based methods for image deraining have achieved excellent performance in terms of reconstruction error as well as visual quality. However, these methods are limited in the sense that they can be trained only on fully labeled data. Due to various challenges in obtaining real world fully-labeled image deraining datasets, existing methods are trained only on synthetically generated data and hence, generalize poorly to real-world images. The use of real-world data in training image deraining networks is relatively less explored in the literature. We propose a Gaussian Process-based semi-supervised learning framework which enables the network in learning to derain using synthetic dataset while generalizing better using unlabeled real-world images. Through extensive experiments and ablations on several challenging datasets (such as Rain800, Rain100H and DDN-SIRR), we show that the proposed method, when trained on limited labeled data, achieves on-par performance with fully-labeled training. Additionally, we demonstrate that using unlabeled real-world images in the proposed GP-based framework results in superior performance as compared to existing methods.

1. Introduction

Images captured under rainy conditions are often of poor quality. The artifacts introduced by rain streaks adversely affect the performance of subsequent computer vision algorithms such as object detection and recognition [12], [28], [41], [4]. With such algorithms becoming vital components in several applications such as autonomous navigation and video surveillance [37], [25], [36], it is increasingly important to develop sophisticated algorithms for rain removal.