Most sensors are (micro-) bolometers, although most recently some "quantum dot IR sensors" seem to have emerged.
"Image processing" within the context of thermal imaging is hardly more than calibration, histogram generation and false color display. Maybe you should add some noise reduction techniques.
If interested you may dug deeper on the FLIR Systems' site as they are now selling the imaging sensors: I'd expect to get some support there - eventually after signing some NDA.
Hello, thank you very much for the information. I am working on thermal cameras that can be used to inspect power lines so that any damages to the insulators can be captured by these thermal cameras due to the difference in the temperature of the damaged insulator. So I need to know whether the bolometer sensor in the thermal camera alone does the job or any algorithms will be used to convert a normal image into a thermal image.
It's the bolometer sensor that does "the whole thermography job".
If there is some "classical" image sensor (visual range) as well, this one is for documentation purposes as thermography images are hard to relate to the "real world" (due to low resolution, imaging properties not targeting the depiction of the reals world scene etc.)