Dependence of the morphology indicators uncertainties on S/N, estimated from mock images. The median trends of the mock galaxies with different n are marked with dotted lines; the shaded region indicates the 16th to 84th percentiles. The top row shows the difference between the measured parameters and the intrinsic values, expressed as ΔC = C_mock − C_int. The bottom row shows the difference between the measured and true n and Re values, relative to the true value. The horizontal dotted line at zero indicates perfect agreement between measurements and true values, while the vertical dashed line marks the S/N = 3 boundary beyond which the agreement considerably improves.