**5. Conclusions**

We proposed the Retinex-based fast enhancement method in this paper. This method can address uneven brightness and greatly improve the brightness of low-light areas. The proposed method is more efficient. In general, the proposed RBFA algorithm performance is better than other state-of-the-art methods, combining the results of the comparative experiment, computational complexity comparison and quality assessment. In other words, the proposed RBFA method is a simple and efficient low-light image-enhancement algorithm.

**Author Contributions:** Conceptualization, S.L.; methodology, S.L.; software, W.L.; validation, L.H.; formal analysis, W.D.; investigation, L.H.; resources, Y.L.; data curation, L.H.; writing—original draft preparation, S.L.; writing—review and editing, S.L.; visualization, W.L.; supervision, W.L.; project administration, Y.L.; funding acquisition, Y.L. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by Science and Technology Department of Sichuan Province, gran<sup>t</sup> number 2020JDRC0026.

**Acknowledgments:** This work was supported by Science and Technology Department of Sichuan Province, People's Republic of China.

**Conflicts of Interest:** We declare that we do not have any commercial or associative interest that represents a conflict of interest in connection with the manuscript entitled 'Retinex-Based Fast Algorithm for Low-Light Image Enhancement'.
