Yehudi lights are lamps of automatically controlled brightness placed on the front and leading edges of an aircraft to raise the aircraft's luminance to the average brightness of the sky, a form of active camouflage using counter-illumination. They were designed to camouflage the aircraft by preventing it from appearing as a dark object against the sky.
Yehudi lights fitted to engine cowling and leading edges of a Grumman TBM-3D Avenger
A maritime patrol Catalina, painted as bright as possible—white—to minimise visibility against the sky, still mainly appears dark. Yehudi lights match brightness better by generating light.
Yehudi lights were tested in B-24 Liberators from 1943.
Yehudi Lights plywood prototype created in the winter of 1943 to demonstrate the concept of counter-illumination using forward-pointing lights on a B-24 Liberator.
Active camouflage or adaptive camouflage is camouflage that adapts, often rapidly, to the surroundings of an object such as an animal or military vehicle. In theory, active camouflage could provide perfect concealment from visual detection.
Cephalopod molluscs such as this cuttlefish can change color rapidly for signaling or to match their backgrounds.
Four frames of a peacock flounder show its ability to match its coloration to the sea bed around and beneath it.
Yehudi lights prototype raised the average brightness of a Grumman Avenger from a dark shape to the same as the sky.
An invisibility cloak using active camouflage by Susumu Tachi. Left: The cloth seen without a special device. Right: The same cloth seen through the half-mirror projector part of the Retro-Reflective Projection Technology
