so there’s an optimization problem in there somewhere

The optimization problem is actually the point of the study, encoded as PPD, which represents the density of a display’s pixel per degree of your eye’s field of vision. It says that any more than 53-94 PPD is imperceptible to most. You can see if your display makes the cutoff if you have the viewing distance and screen size here:

www.cl.cam.ac.uk/research/…/display_calc/