A: snapshots of the stellar mass density from the simulation of two colliding galaxies with prograde-prograde orbit coupling, at different times. The images have a physical scale of 200 pc pixel⁻¹, comparable to the observations (assuming the median redshift of our galaxies of ≃0.7). B: mock HST F814W observations obtained from the above simulated cutouts after conversion to the ∼0.095″ PSF resolution of the images (through a Gaussian filter) and addition of the noise. For each step, the instantaneous SFR and the estimated clumpiness are indicated in the corner. 24 M_⊙ yr⁻¹ is the SFR of two isolated disks, according to the fiducial run. C and D: same as panels A and B, but for a retrograde-retrograde collision.