Recovery of star formation histories. The four panels show a CSP at 3, 5, 7 and 11 Gyr from the onset of the SFH. Black vertical lines represent the exponentially delayed SFH (τ = 0.3 Gyr) assumed for the input spectra (rebinned according to the age step of our library models), while vertical lines represent the output SFH; horizontal arrows indicate the time from the beginning of the SF (i.e. 3, 5, 7 and 11 Gyr, respectively), while grey vertical lines mark the asymmetric age ranges around the SFH peak defined in the text for CSPs younger or older than 5 Gyr (i.e. [−1; + 0.5] and [−1.5; + 1], respectively).