Simulated HST imaging data used for the blind lens modeling experiment (see Sect. 4 for details). The top left panel shows a zoom-in cutout of the data. The top right panels shows the true (unlensed) source surface brightness. The bottom left panel shows the true PSF kernel downscaled to the data resolution (and given to the modelers). The bottom right panel shows normalized residuals in image plane obtained with a too simplistic source model (a single Sérsic profile).