Empirically estimated shape noise, σ_tot (Eq. (6)), with (dashed blue lines) and without (dashed orange lines) multiplicative bias correction, compared to the detection bias–corrected intrinsic shape noise (solid green lines), σ_int (Eq. (7)), as a function of input magnitude. Upper panels: Comparisons for Euclid-like setups. The difference between the grid-based and randomly placed configurations is negligible; however, in both cases, applying the bias correction slightly overestimates the shape noise likely arises from second-order effects that are not captured in the multiplicative bias correction. Lower panels: Comparisons for LSST-like setups. For randomly placed galaxies, the corrected σ_tot rises significantly for magnitudes ≳23.5 relative to the grid case, indicating that blending effects become increasingly important at fainter magnitudes.