Top: predicted I-band LFs at solar chemical composition and scaled-solar chemical mixture for ages ranging from 7 to 14 Gyr (solid lines). The faint peak at the bottom end of the LF is caused by the WDBTO. Bottom: same as the panel, but for K-band LFs (solid lines). The faint peaks are caused by the WDRTO, while the bright secondary maximum centered at M_K ~ 13.2 mag is caused by the CIA-induced blue TO (see text for more details). The dashed lines in both panels display the same LFs, calculated from large synthetic WD samples including a 1σ photometric error equal to 0.05 mag in both I and K (see text for details).