The Elements and Principles of Design.
Emphasis-At first glance u see the 2 chairs and the table which are focal point of the image. You are drawn to this by everything else looking similer in shape and colour and by the sides looking like a hallway to make the focal point stnad out more from everything else. They are also centered in the image.
Unity- Unity is portrayed here due to the walls seeming coherent and conected to the same place. The shape made by the floor, ceiling and walls looks like a bottle.
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