This picture was taken with film sensitive to INFRARED LIGHT at wavelengths near 9 µ (microns, or one millionth of a meter). You can see that the person radiates at 9m as does the match, but notice that the walls in the background do not, meaning that the walls are much colder than this person is. The walls do radiate their own light but at wavelengths longer than infrared, because the walls are cooler than either Jason or the match. If our eyes could respond to wavelengths of infrared light, we'd be able to see each other in the dark. Our eyes can't, but a rattlesnake's eyes can! And so can military-issue night goggles! When you look at a person with these, you're seeing the light the person himself is making and radiating. Infrared goggles and infrared cameras allow us to see light that our eyes alone canNOT see. The goggles register infrared wavelengths and translate them into an arbitrary color of visible light which we CAN see. This is called FALSE COLOR. In this picture, the different colors correspond to different intensities of light at 9m. Here, the developer of the picture chose white to indicate the strongest or brightest light at 9m and blue to show the dim areas at 9m .

In false-color images the colors chosen are completely arbitrary and are up to the whim of the astronomer making the image or the engineer making the infrared goggles.