This picture is coincidence of tone. The subject is “a person.”
The lighting scheme coincides with the subject, and the person
is revealed.
Even though the first two pictures are both silhouettes, one is
coincidence and the other is noncoincidence. The actor
standing in the doorway of the third picture may be in
silhouette like the second, but the subject is not a face. The
subject is “a person standing in the doorway.” Even if the
person was well lighted, the audience couldn’t see the face,
because the actor is too far away. This last picture is
coincidence because the tonal organization clearly reveals the
subject.