(1) The following signs shall not be subject to the provisions of this Section,
(a) signs for regulating traffic or similar devices, legal notices or warnings at railroad crossings,
(b) signs in display windows including writing, representation, painting or lettering directly on the surface of any window or door, or other signs not affixed to the building interior,
(c) small signs displayed for the direction of the public including signs that identify rest rooms, freight entrances and such other similar directional signs,
(d) signs painted directly on a building, and
(e) incidental signs or other signs subject to municipal approval.