Thermography, or thermal imaging, is a type of infrared imaging. Thermographic cameras detect radiation in the infrared range of the electromagnetic spectrum (roughly 900Ð14,000 nanometers or 0.9Ð14 µm) and produce images of that radiation. Since infrared radiation is emitted by all objects based on their temperature, according to the black body radiation law, thermography makes it possible to "see" one's environment with or without visible illumination. The amount of radiation emitted by an object increases with temperature, therefore thermography allows one to see variations in temperature, hence the name. With a thermographic camera warm objects stand out well against cooler backgrounds. Humans and other warm-blooded animals become easily visible against the environment day or night, hence historically its extensive use can be ascribed to military and security services.
