The thermal cameras mounted in our products have the function of FFC.
There is a shutter between the thermal camera sensor and the lens. This shutter is used to perform a flat-field correction, or FFC.
Flat field correction (FFC) is a method to remove non-uniformities in the image caused by different sensitivities of the pixels and by distortions caused by optics.
The FFC process takes about one-half second that employ an internal shutter. While the shutter is in the field of view of the sensor, the image just prior to the shutter moving is frozen and displayed until the FFC process finishes and the shutter moves out of the field of view of the sensor.