Example of spectrosynthesis. Panels on the left show the synthesis for C while panels on the right show the synthesis for N. The upper row shows the synthesis for the MS target #1_13, the middle row shows synthesis for the HB target #RHB_I_a_40848, and the lower row shows the synthesis for the SGB target N104e_51104. The wavelength range used for the abundance determination is shown as a shaded region. Observed spectra are in green. Red spectra show the best match, while blue and black spectra represent abundance variations of ±0.5 dex for C respectively, while for N we used ±1.0 dex for low resolution spectra of MS and SGB stars (upper panel) and ±0.5 dex for intermediate and high resolution spectra of SGB, RGB, HB and AGB stars (middle and lower panel).