Reconstructed spectrum (left) and latent representation (right) of a PHOENIX-ACES synthetic spectrum for one of the trained AEs. Left panel: comparison of the original (blue) and reconstructed (red) spectrum. Both spectra overlap as they are almost similar. The title shows the stellar parameters of the synthetic spectrum. Reconstruction residuals (original-reconstructed) are shown in the bottom panel. Right panel: 32-dimensional latent space of the input spectrum obtained by the encoder, reshaped to a 8×4 matrix only for a better visibility. The colour scale indicates the strength of the features. The decoder uses this compressed representation to obtain the reconstructed spectrum.