  By performing general relativistic radiative transfer calculations, we show
the radio images of relativistic jets including highly magnetized regions
inside jet funnels, based on steady, axisymmetric, and semi-analytic general
relativistic magnetohydrodynamics models. It is found that multiple ring images
appear at the photon frequency of 230 GHz for nearly pole-on observers, because
of the strong light bending effect on photons generated at the separation
surfaces which is the boundary between the inflow and outflow flows in the jet
funnel. A bright teardrop-shaped component, which extends from the bright rings
of the separation surface, also appears in the counter jet region. The diameter
of the brightest outermost ring originated from the counter jet is $\sim 60 ~
\mu {\rm as}$, which is consistent with the ring-like images of M87 at 86 GHz
observed with GMVA, ALMA and GLT, whose ring-diameter is $\sim 64^{+4}_{-8}
~\mu {\rm as}$. The thinner and smaller-diameter rings are exhibited when the
black-hole spin magnitude is higher. These morphological features are expected
to appear without being prominently affected by the detailed MHD-plasma
parameters of our GRMHD jet model, since the location of the separation
surfaces is mainly regulated by the black hole spin. Our GRMHD model and the
emission features of the images in the horizon-scale, highly magnetized jet
funnel may be tested by future observations, e.g., the next-generation Event
Horizon Telescope and the Black Hole Explorer.
