Multiplicative detection bias μ_det as a function of the background noise level, which is multiplied by a factor f_noise with respect to the baseline case. The black and red lines correspond to the baseline and grid-based cases, respectively. The solid lines show results for galaxies with 20 < m_AUTO < 24.5, whereas the (light-coloured) dashed lines indicate the bias if we select using the input magnitudes, 20 < m_input < 24.5. In the latter case the bias vanishes for the grid-based case as the noise level is low, but for the baseline case the bias plateaus to μ_det = −0.0024 as a result of blending.