Extreme emission-line galaxy (Plate-MJD-Fiber 391-51782-353): PCA and VAE reconstructions of the O II 3726/3729 (left) and Hα and S II emission lines (right). The median S/N of the spectrum is 9 in the left panel and 13 in the right panel. While the PCA reconstruction of the strong O II 3727 line gets better with more components, the VAE reconstruction does not improve after four parameters.