Socks, thermogram footage. Thermography records the temperature of surfaces by detecting long-wavelength infrared radiation. The colours show variations in temperature. The scale runs from white (warmest), through yellow, orange, red and purple to blue (coldest). A colour-coded temperature scale is at right, ranging from 20 degrees Celsius (dark blue) to 33 degrees Celsius (white). This footage shows the heat being radiated from the feet of a person wearing socks. The toes are hotter than the ball of the soles of the feet. The feet overall are radiating more heat than the legs, which are insulated by more layers of clothing.