Stroking a dog's head. Thermographic footage of a human using their hand to stroke a dog's head. This action can reduce stress in what is known as animal-assisted therapy. A thermogram shows variation in temperature on the surface of an object, measured by the long-wave infrared radiation it emits. The temperature scale is colour-coded from black (cold) through purple, blue, green and yellow to red and white (hottest). This thermogram footage shows that the dog is warmer than the human's hand, with its eyes the warmest part.