Examples modelling stellar populations. Each panel displays the complete modelled spectral range in the upper row and three zooms in key spectral regions in the lower row. The observed spectrum is in black and the modelled stellar spectral energy distribution in light blue. Masked spectral ranges are marked using bands with green stripes in diagonal. The positions of the DIBs at λ5780 and λ5797 are marked in the central zoom of each panel with red ticks. Upper row: two red spectra without DIB detection. Lower row: two blue spectra without DIB detection. Reported wavelengths here and throught the paper are in rest-frame.