Half-light radius dependence upon the optical depth of a single cloud for different wavelengths of 0.1 (solid line), 0.3 (dashed), and 1μm (dotted). Radius is expressed in the units of the standard disc half-light radius at the same wavelength. Black hole mass M_BH = 10⁸M_⊙ mass accretion rate ṁ = 10, temperature limits 10³ (left), and 10⁴ K (right). The disc is seen face-on, θ₀ = 45°.