Field IR transmittance through emissive smokes: Method for extracting radiance from thermal imaging

In a smoke environment, target recognition is a pivotal problem faced by imaging-guided weapons and reconnaissance equipment. In fact, the transmittance of smoke is the main hindrance to recognition. In this study, a numerical method for extracting pixel radiance to calculate infrared (IR) smoke transmittance is proposed. First, a description of the field test and the equation governing the transmittance of IR smoke are introduced. Next, a method for extracting pixel radiance from an IR image is presented; specifically, a scheme that uses a bicubic interpolation algorithm, to calculate the radiance of the background pixels is presented. Finally, the steps of the method are illustrated through a test example. The results show that the new method eliminates the anomaly of the transmittance value being less than 0 or greater than 1, and in addition, yields sufficiently accurate solutions for engineering applications.