Isothermal imaging makes it possible to configure highlighted temperature-spans in the image. They help to define which temperature corresponds to which color. The Lower limit denotes the temperature where the colored part of the palette will start and all temperatures above this limit will stand out.
Spot temperature reading
This capability is used to view the temperature of a particular area of the image. The emissivity can also be adjusted (depending on the material characteristics) to get a more precise reading. Used as a visual aid for an operator.
For a list of emissivity for different material,