Analogous Maxwellian Algorithm for photon geodesic calculation in General Static Isotropic Metrics

In this manuscript, we present an alternative method for calculating null geodesics in General Static Isotropic Metrics in General Relativity and Extended Theories of Gravity. We apply a conformal transformation to pass from curved to flat spacetimes, Maxwell's equations are solved and then photon geodesics are calculated. The curvature is encoded in the dielectric and magnetic properties of the medium. We apply this method in different black hole and wormhole metrics obtaining an excellent agreement with relative errors below 1.11% with respect to the analytical solutions in the original gravity framework. Finally, we provide the image of a Schwarzschild black hole surrounded by a thin accretion disk which is also very faithful and accurate (within 1.11% of relative error) with that proposed originally by Luminet.