Kirlian photograph of the palms of a woman's hands. Kirlian photography is also known as electrophotography, high voltage photography, radiation field photography and corona discharge. The technique obtains a photographic image due to interactions between the subject and an applied electric field. No external light source is used; light emitted as photons from the electrical interaction causes the image on film. A controversial medical application of the technique involves correlating the physical and mental well- being of a subject with image variations arising from differences in sweat rate and sweat composition on the skin surface.