Relative error q defined in Eq. (36) for synthetic companions injected in the scientific data of HIP 65426 (with the same spectra as the host star) as a function of the angular separation, ρ_⊕ − ρ_★, and for contrasts of χ = 3 × 10⁻⁵ (blue), 2 × 10⁻⁴ (orange), and 2 × 10⁻² (green). The grayed area represents the region invalidated by the coronagraphic mask. The angular separations of the three cases presented in Fig. 11 are highlighted by the dashed lines labeled A, B, and C.