A method for obtaining a reflectance image from a plurality of thermal images utilizes a technique of A) obtaining a first thermal image of a subject, the first image containing both temperature and reflectance data; B) changing the environmental temperature of the scene, C) obtaining a second thermal image of the subject, the second image containing both temperature and reflectance data from the scene with said changed environmental temperature; and D) deriving a third image from the first and second images, that third image being essentially a reflectance image. In one embodiment, the third image is derived by subtracting the data in the first image from the data in the second image, or subtracting the data in the second image from the data in the first image. In another embodiment, either of the first or second images are processed along with the third image to produce a temperature image substantially devoid of reflectance information. A system for performing such techniques is also disclosed.