“the darkened room” refers to an 18th century optical device like a camera, invented to capture a projected image through a small pin-hole and reflect it onto a screen contained on the box – preserving both the perspective and color. Image: Johannes Vermeer: “The Art of Painting,” 1666, collection, Kunsthistorisches Museum, Vienna300px-Jan_Vermeer_van_Delft_011.jpg en.wikipedia.org

camera obscura