Conditional evolution is crucial for generating non-Gaussian resources for quantum-information tasks in the continuous variable scenario. However, tools are lacking for a convenient representation of heralded processes in terms of quantum maps for continuous variable states, in the same way as Wigner functions are able to give a compact description of the quantum state. Here we propose and study such a representation, based on the introduction of a suitable transfer function to describe the action of a quantum operation on a Wigner function. We also reconstruct the maps of two relevant examples of conditional processes, that is, noiseless amplification and photon addition, by combining experimental data and a detailed physical model. This analysis allows us to fully characterize the effect of experimental imperfections in their implementations.