The area of a sign shall be construed to include all lettering, wording, and accompanying designs and symbols, together with the background, whether open or enclosed, on which they are displayed, including any border framing or decorative attachments, but not including any supporting framework or bracing incidental to the display itself. Where the sign consists of individual letters or symbols attached to a building, wall or window, the area of the sign shall be considered to be that of the smallest rectangle or other regular geometric shape which encompasses all the letters and symbols.