Normalization of Infrared Facial Images under Variant Ambient Temperatures

Abstract

This chapter dedicates to eliminate the effect of ambient temperatures on thermal images. The thermal images of a face are severely affected by a variety of factors, such as environmental temperature, eyeglasses, hairstyle and so on. To alleviate the ambient temperatures variations, three methods are proposed to normalize thermal images. The normalization based on transformation uses the function obtained by the block and least squares method. It should be highlighted that psychological (e.g., happy, angry, and sad etc) and physiological (e.g., fever) conditions also affect the thermal patterns of faces.