Magnetostatic interactions in perpendicularly magnetized Co/ Pt bilayers lead to the formation of mirror domains in both soft and hard layers. We show that it is possible to take advantage of domain replication in order to probe the microscopic domain configuration of the hard layer through macroscopic hysteresis minor loop measurements on the soft layer. The minor curves consist of two loops, which magnetization amplitudes and field shifts can be quantitatively related to the domains sizes, shapes, and up/down relative proportion in the hard layer.