The Technology Behind Thermal Imagining To Detect Swine Flu
From these equations we can easily see that wavelength generated with human body temperatures are on infrared (IR) range. So the thermal imaging scanner is basically a IR camera which picks up IR radiations emitted by the body.
Then from these scanner data imaging software apply different colors for different wavelengths. Normally from blue for colder bodies to red for hot bodies. In the case of Swine Flu detection room temperature is set as blue (25-32°C) and normal body temperature (37°C) is set as orange color.
When a person with fever is scanned, the IR emitted by that person will be higher and these wavelengths are shown as red and then can easily detected visually or automatically create alarms to indicated fever detection.