Infrared imagery is often a grayscale picture whose scales (or shades of gray) represent the differences in temperature and emissivity of objects in the image. As a general rule, objects in the image that are lighter in color are warmer and darker objects are cooler. No object in the images is detected via visible light wavelengths (400-700 nanometers) rather, only from infrared wavelengths in the 3000-5000 nanometers or 3-5 micrometers (microns) range. Lights and other relatively hot objects are very evident, but as a result of their heat--not light emissions.

When an image is taken by an infrared camera it is often recorded on videotape and later converted to a digital image file with the help of a computer. The image may be then modified in a number of ways to enhance its value to the end user. In the case of the printouts enclosed with this package, the roof images were digitized from the original Super VHS or Hi-8 video tape, then adjusted for contrast and brightness before being scaled and placed in Microsoft PowerPoint file. The PowerPoint file was printed by high resolution ink jet technology.

The highest resolution infrared images are usually found on video tape, while the printed pictures may be used as a convenient reference when making the building drawings or accompanying a roof report. Areas of roof moisture contamination often manifest themselves as warmer (lighter colored) areas that may be nebulous in shape and sometimes mottled in appearance, although they are commonly found in linear or puddle-like shapes. The linear shapes many times follow low areas, drainage routes, roof edges and seams. Puddle-like round or oblong shapes often form around roof penetrations such as mechanical equipment, standpipes, vents and drains. The wet areas are lighter in color because the latent heat (from daylight sunshine) in the trapped water mass is greater than in the dry, functioning insulation or roof substrate. After sunset when the roof structure cools down, wet areas of roof insulation and other materials continue to radiate heat, allowing the sensitive infrared camera to detect the sources of heat and record them for later analysis..