Illustration of model fitting to 1D spatial profiles. Left column: each row shows the 1D spatial profile (blue) with individual model components for a single lens system. The model components are Moffat profiles, which represent the deflector and lensed quasars, with an additive polynomial function representing the background. The profile component representing the deflector is marked black and other profile components generally representing the lensed quasar images are marked with yellow. Right column: the top panel in each row shows the 1D spatial profile (blue) with 1σ uncertainty (orange) and the corresponding model (green) that fits the data in that profile. The bottom panel shows the residual (red) between the data and the model normalised to the uncertainties in data. The uncertainties on the spatial profiles of B0445+123 and B0631+519 are higher compared to others because these 1D profiles were generated from single frames, while for other lens systems, the corresponding profiles were generated from coadded frames.