A reflection of yourself appearing on sheet of wood. As the camera “sees” you the computer scans the image quickly to determine the darkness of each pixel of the image. It maps each pixel to a rod on the plane of wood and rotates the rod so it appears the correct shade of light or darkness.
The rods of wood appear to change color just by virtue of the overhead lighting. They’re cut on an angle such that they cast a shadow when rotated to a certain position. Ingenious. It has the interesting property that electric power is required to change the picture, but not to hold it. Once the rods are rotated it could be turned off and you’d still see the face.
What’s the practicality of something like this? Large outdoor signs where you want to be able to update the message; maybe the principle could be applied to flooring (cover with a sheet) so you could update the pattern of a floor; it would be a neat attention piece in a window display of a retail store.