RMS intensity contrast of the quiet Sun in the test continuum filtergram as a function of μ, before (black curve), and after image restoration with K₁ (blue curve) and with K₂ (red curve). The black circles represent the values from the synthetic intensity maps and the green circles the same, rescaled to reflect the proportion arising from spatial frequencies up to the cutoff spatial frequency of the restored (with K₂) test continuum filtergram (see text).