Reply #17: Unless it is a consumer grade thermal image the white is simply the hotest point. [View All]

[Statistical]

Any professional thermal imager will allow a custom range. The actual sensor (very similar to digital camera sensor) has a dynamic range far beyond what you would need to use (say -50 Celsius to 1500 Celsius). So you crop the displayed range by setting the max temp (which shows white) and the min temp (which shows black). The rest of colors are simply points between min and max. Higher quality magers can constantly adjust the dynamic range based on recorded data. So you record everything and it then runs some algorithms to set min & max to provide the most differentiation (detail) between colors bands.

The best analogy to use would be a custom white balance in a digital camera. Except you are calibrating to peak infrared output. It is unlikely that they can't record high temps due to clipping. Recording high temps is easy. It is recording low temps (close to absolute 0) and small temperature changes that is difficult.

Still IF it is indeed clipping (temps beyond max of what is can detect) there would be no way to know what that temp is without knowing the specs of the equipment they are using as any max range would be equipment dependent.