Here are a couple of stereoscopic views of Duchamp’s Tu M’. The painting has a perspectival pictorial structure with three painted shadows of readymades landing on the canvas (not on the objects described in perspectival depth). A real bottle brush sticks out form the canvas and casts a shadow in the same way as the absent readymades.
The pictures are taken from two different horizons.If you are new to this blog, to resolve the stereoscopic pair of images, go cross eyed so that a feature in one image corresponds to the same feature in the other, and try to relax until the depth emerges. If you are having difficulty seeing it, reduce the size of the image on the screen.