Joint distribution of the fluxes, flux ratios, and ionized gas fraction in the Monte Carlo simulations executed for the real images. As is customary, on the diagonal we show the histogram of each quantity; the y-axis for these plots is scaled automatically to include the maximum counts in a bin. The green horizontal bars correspond the 16th and 84th percentiles, which we report as uncertainties, and the horizontal green bar is the best-fit value.