Hou enhances the graphic possibilities of composition through the delimitation of the frame, another aspect of mise-en-scene directly linked to his restricting the camera to predefined axes and the geometricization of space.
This is most readily seen in the hospital lobby, especially in the two frame blow-ups below. In the first scene at the lobby (below, right), we see only the arched entrance with the staircase in the background outside. The space is divided into three areas: the lobby itself, the rooms off- screen, and the space outside the entrance. The graceful, arched doorway creates a second frame inside the film frame, and contains a partially eclipsed stairway that people ascend and descend, emphasizing the off- screen space above the top edge (14:52-15:08). At a latter point in City of Sadness, the camera returns to the hospital lobby and is placed back in a darkened room; the dark walls of the doorway delimit the visible dimensions of the movie screen into an area a sixth of its normal size, in effect creating a third frame (below, right; C 25:59 ~ 26:36). Furthermore, it's now a nearly perfect square. Not only does the space of City of Sadness become fractured into a graphic plane, but the size and shape of the screen itself (at least what is available to the narrative) varies.
Hou's other films use this frame within a frame composition. In Summer at Grandpa's the combination of a staircase and a door cut down the operable narrative space to a tiny square from which the grandpa makes a phone call, as can be seen in the frame blow-up at the top of this page. In a scene from Dust in the Wind, Hou uses two door frames to slice his space into thirds (below). From these examples, it becomes particularly clear that this works in tandem with geometricization to emphasize the graphic qualities of the image.
