Distribution of residual magnitudes between simulated source and best-fit parameters for MUSE Lyman-α NB images in the left panel and HST images in the right panel (see Sect. 3.4). The grey points represent the LLAMAS galaxies. All the objects in the blue dashed contour were selected for spatial fitting with LENSTOOL based on the magnitude difference between input and best-fit parameters (Δ_mag < 0.3). The green dashed contour represents where the spatial fit will recover both the flux distribution and morphological information on the sources as estimated by the fraction of non-overlap between the simulated and fitted sources (see Sect. 3.4).