How are European Landsat products (radiometric corrected or above) calibrated from radiometric corrections point of view?
Basically three kinds of calibration methods could be used for the radiometric correction of TM / ETM+ products: pre-flight or pre launch (PL), in-flight, using lifetime model, Any calibration algorithm computes the calibration gain and bias (offset) of each detector band. It determined the detector Look Up Tables (LUTs) to be applied for the generation of the radiometric corrected image. For TM instrument, the pre-flight calibration procedure uses heuristic look up table estimated in laboratory before the launch in order to estimate the calibration gain. The analysis of the dark current as part of Internal Calibration (IC) data is used to estimate the calibration offset. Obviously, after 25 years of TM instrument operation, the value defined before the flight do not account for the detector ageing. So that, the pre flight calibration is not valid anymore. The IC system is a part of the TM and ETM+ instruments. The response of the detector to a Lamp signal for which the radiance is wel
