Image simulations, with bright galaxies on a grid (left), and with the faint galaxies down to magnitude 29 added, including clustering properties (right). The upper panel shows noiseless simulations and the bottom one simulations with realistic Gaussian noise. This sub-image presents nine tiles of each. The scale is given by the red line in the upper left panel. The numbers in the same panel correspond to the magnitudes of the bright galaxies. The two right panels are populated with an identical set of 30 faint galaxies.