The vicinity of supermassive black holes (SMBHs) has been in the focus of scientific research for decades. Open questions revolve around the types of compact massive objects in the centers of galaxies, plasma dynamics around them and emission processes at play. The goal of this study is to assess whether it is possible to distinguish between two spacetimes in observations of such objects and their environment by means of synthetic imaging. To this end, general relativistic radiative transfer (GRRT) calculations are carried out on general relativistic magneto-hydrodynamics (GRMHD) simulations of a Kerr- and of a non-rotating dilaton black hole. We
parametrize the proton-to-electron temperature ratio and analyze the source morphology. From the GRMHD simulation and GRRT images, we conclude that differences are hard to detect in a real-world observation scenario, especially for jet-dominated images. The differences can be explained by the absence of rotation in the dilaton system and the matching of the black holes at
their innermost stable circular orbit.