Synchrotron-radiation imaging serves as a powerful tool for the non-destructive material characterization of metallic foams. The foaming process is visualized in situ by real-time radiography in projection image sequences. The temporal evolution of foam expansion from early pore formation over pore growth up to the collapse of the foam structure are reported. Ex situ microtomography is applied to the study of statistical distribution properties at the early foaming stages. Various image processing and analysis techniques yield quantitative results concerning pore nucleation and their early formation, film rupture and foam drainage. The similarities and differences of the metal foaming process with respect to the precursor material, its processing steps and process parameters are determinable.