Pseudo-Supervised Low-Light Image Enhancement With Mutual Learning

Low-light image enhancement (LIE) is important for many high-level vision tasks as the poor visibility of underexposed images can severely degrade the performance of the subsequent image recognition, analysis, etc. Although recent deep-learning-based LIE methods exhibit promising performance, most of them require a large number of paired training images, thereby limiting the practicability to real scenarios. In this paper, we propose a pseudo-supervised LIE method with the integration of mutual learning. Specifically, for the given low-light image, we first use a quadratic curve to generate a pseudo-clear image, which is served as the auxiliary ground truth for supervision, then the pseudo-paired images are simultaneously input to two parallel homogeneous branches to learn the expected enhanced result through the knowledge distillation of two branches via mutual learning. As both the generated image and the input low-light image underlies the desired solution, the mutual learning strategy enables the two branches learn from each other and produce the final results. Extensive experiments demonstrate that the proposed method outperforms most existing unsupervised LIE methods in terms of both qualitative and quantitative evaluations, and also achieves competitive performance against many supervised and semi-supervised methods.