Black Light Vision create the black light effect through the iPhone camera.
A black light, also referred to as a UV light or ultraviolet light, is a lamp that emits ultraviolet radiation (UV) in the long-wave (near ultraviolet, UVA) range, and little visible light. Other types of ultraviolet lamp emit large amounts of visible light along with the ultraviolet; but a "black light" usually refers to a lamp that has a dark blue optical filtering material in the glass envelope of the bulb (or the lamp housing) which blocks most of the visible light, so the lamp emits mostly ultraviolet.