Pre-emptive Shadows: Eliminating the Blinding Light from Projectors

Users interacting with front-projected displays often work between the projector and the display surface. This causes undesirable projection on the user as well as temporary blindness from looking into the bright light of the projector. In this paper, we present pre-emptive shadows, a technique that uses a camera-projector system to detect and turn off pixels that would otherwise be needlessly cast upon users’ bodies, especially their faces. We present measurements that show that system reduces the brightness of the blinding light by about a factor of 5.