I was fooling around with the scanner today making crazy pictures when this idea happened.
Sfumato, from the Italian word sfumare "to evaporate like smoke," was a renaissance painting technique which used subtle and gradual shading to produce soft forms. These portraits, made using polyester pillow stuffing placed directly on a scanner bed, reminded me of the smoky technique.
Here are some pictures of how it was done.
When you invert the colors of this image, the face becomes apparent.