1. A method of detecting a human being from objects in a field of view, the method comprising: (a) capturing an image in the field of view with an infrared camera; (b) capturing the image in the field of view with another device; (c) determining first areas of the image that fall within a temperature range, the range being indicative of thermal emission characteristics of the human being based on output from the infrared camera; (d) determining second areas of the image that correspond to characteristics of the human being based on output from the other device; (e) subtracting the second areas of the image from the first areas of the image to define third common areas; and (f) determining that the third common areas include a human being.