Top and central rows: synthetic stellar disk images in the optical filter for the four simulations of Table 1 having log g = 2.2. The intensity range is [5000, 1.5 × 10⁶] erg cm^-2 s^-1 Å^-1 for [Fe/H ]  = 0.0 and −1.0; [5000, 2.0 × 10⁶] erg cm^-2 s^-1 Å^-1 for [Fe/H ]  = −2.0 and −3.0. Bottom panel: fluctuations of the synthetic visibility curves derived from the above images. The colors have the same meaning as in Fig. 3. We dropped the first lobe of the visibility curves as in Fig. 7.