How accurately can the camera measure an absolute temperature?
Most FLIR Thermography cameras have a specified accuracy of ±2 ºC (±3.6 ºF) or ±2% of reading.
100 °C or lower: ±2 °C,
200 °C: ±4°C
SC660 is specified ±1 °C or ±1% of reading.
This means that any camera, at any environment condition (within specification), at any time will give a reading within the accuracy specification.
However, one particular camera, at the same environment condition, will have a statistical repeatability of measurement that is much better than this. Typically close to the NETD value. This is also applicable when you compare adjacent pixels.
For specific applications such as fever screening, there is an averaging function implemented that makes absolute accuracy specification unneccessary. The averaging function sets a reference value from a series of “normal” readings, and gives an alarm if one single reading differs more than a certain limit.