The Image Fulgurator is a device for physically manipulating photographs. It intervenes when a photo is being taken, without the photographer being able to detect anything. The manipulation is only visible on the photo afterwards.
Technically, the Image Fulgurator works like a classical camera, though in reverse. In a normal camera, the light reflected from an object is projected via the lens onto the film. In the Image Fulgurator, this process is exactly the opposite: instead of an unexposed film, an exposed and developed roll of slide film is loaded into the camera and behind it, a flash. When the flash goes off, the image is projected from the film via the lens onto the object.