  A constituent quark model based on the spectator formalism is applied to the
gamma N -> N* transition for the three cases, where N* is the nucleon, the
Delta and the Roper resonance. The model is covariant, and therefore can be
used for the predictions at higher four-momentum transfer squared, Q2. The
baryons are described as an off-mass-shell quark and a spectator on-mass-shell
diquark systems. The quark electromagnetic current is described by quark form
factors, which have a form inspired by the vector meson dominance. The valence
quark contributions of the model are calibrated by lattice QCD simulations and
experimental data. Contributions of the meson cloud to the inelastic processes
are explicitly included.
