Tested and works perfect!
If you are open to ideas will be great a parameter to say the intensity/tolerance of ilumination. I mean, in case the image have a lot of white tones(Or dressed as white or anything) will be odd, so a slider with a intensity from 0-100(for example) will be useful.
Example (maybe a 55, 50 and 45 number):
And if you still are open to more, an option to randomize/speed form X to X values and get an image where the thermal is changing more-less and seems he is breathing or something