Difference image between the V-band scattered flux computed assuming the HG phase-function (F_HG) and a pseudo-isotropic one (F_{g − fac}), computed for a dust disc with a half-opening angle of 30° viewed from an angle of 45° from the rotation axis using a dust model composed of amorphous carbon and silicates. The region of the disc at δ ≤ 0 is the near-side of the disc. The HG function reproduces the strength of forward scattering much more effectively, with differences between the two methods of up to an order of magnitude, although the integrated scattered flux is the same using both methods.