  Libraries of stellar spectra, such as ELODIE (Prugniel & Soubiran 2001),
CFLIB (Valdes et al. 2004), or MILES (S\'anchez-Bl\'azquez et al. 2006), are
used for a variety of applications, and especially in modelling stellar
populations (e. g. Le Borgne et al. (2004)). In that context, apart from the
completeness and quality of these spectral databases (Singh et al. 2006), the
accurate calibration of stellar atmospheric parameters, temperature (Teff),
surface gravity (log g), and metallicity ([Fe/H]), is known to be critical
(Prugniel et al. 2007; Percival & Salaris 2009). We discuss the technique of
determining stellar atmospheric parameters accurately by `full spectrum
fitting'.
