  The internal image of the proton is unveiled by examining the generalized
parton distributions (GPDs) at zero skewness, within the basis light-front
quantized environment. Several distributions emerge when a quark is sampled
with different currents depending upon the helicity arrangements of the active
quark and the proton target. We investigate six of the eight leading-twist
proton GPDs of the valence quarks, the helicity conserving distributions $(H,
E, \tilde{H})$ and the helicity non-conserving $(H_T,E_T,\tilde{H}_T)$
distributions at skewness set to zero ($\zeta=0$). We consider purely
transverse momentum transfer and, hence, obtain results describe only the
proton's two-dimensional structure in the transverse plane. We present the
Mellin moments of these distribution functions, where the first moment produces
a form factor and the second Mellin moments help extract the information on
partonic contributions to the hadronic angular momentum. We compare our results
for the Mellin moments with those from lattice QCD and other approaches where
available. We also present the GPDs in transverse position space.
