Synthetic images of slab power-law model which was further improved by a “spot” (that is a spherical structure between the primary and secondary, partly hidden inside the slab). The total (not reduced) χ² value was decreased from 105 202 (without the spot) down to 102 005, which is a significant improvement. Four wavelengths are shown: λ = 155 nm (FUV), 545 nm (V band), 1630 nm (H), and 4750 nm (M).