A. Pereira, L. Fernandes, and A. Conci.
"Image preprocessing techniques for facial expression classification", in <em>Proceedings of the 2nd Life Improvement in Quality by Ubiquitous Experiences Workshop</em>, Aveiro, 2022, pp. 5-8, doi: <a href="https://doi.org/10.5753/lique.2022.19995">https://doi.org/10.5753/lique.2022.19995</a>.