  Recently, $4f$ system containing a q-plate has been used to perform edge
detection and enhancement of amplitude and phase objects. However, only few
studies have concentrated on edge enhancement of phase-amplitude objects. Here,
we experimentally verified the functional difference between scalar and
vectorial vortex filtering using an onion cell, the experimental results agree
well with theoretical analysis. We verified our experimental results through
numerical simulation. Although vectorial vortex filtering successfully enhanced
the edges of phase and amplitude objects in the phase-amplitude object, they
are indistinguishable due to the equal enhancement of the edges of the phase
and amplitude objects. To address this, we propose a method to isolate the edge
of the phase object from the edge of the amplitude object using off-axis beam
illumination. We theoretically calculated the isolation of the edge of the
phase object from the amplitude object, and verified via numerical simulations.
