if you accept that sense data exists outside of you, then once in a while you might like to consciously fashion some coherence over time for it. You might like to imagine that threaded through the stream of sense data there are reoccurring forms.
And you might like to start screwing with those forms. You might like to alter the combinations in which you imagine you could find them. And after some time, screwing around like this, you'll eventually start deciding what these forms really stand in for if anything at all.
And doing that consciously is "using" Ni (and judgment).
But, in my humble estimation, perception doesn't and can't exist only at the conscious level. No one, for instance, can "do" conscious Se without some idiosyncratic unconscious information in the background that makes the Se "yours". That unconscious information would be lower level Ni. And likewise, there is no conscious Ni without lower level Se since no one makes idiosyncratic connections between bundles of concepts without some unquestioned starter data of the "out there" seen first.
But it seems like in the OP you might have set up extroverted perception as the "real" perception, in which case, yeah, Ni is one of the "reverse" perceptions.