In Nighthawks by Edward Hopper he used the bright color in the diner against the mainly dark piece to create contrast. The same teal hue throughout the piece creates unity. The patterns below the windows creates reputation which creates unity. The girl in the red dress is a focal point because red is only used in the piece on her and red is an attention getting color. When viewing the piece your eyes are drawn to the diner and then once there your eyes move to the girl and then all around the diner. Overall this piece is a very good piece both technically and visually.