The radiometric photogrammetry calibration report is based on a series of 60 flat field images for each aperture size and sensor. The flat field is illuminated by eight normal light lamps with known spectral illumination curves.
These images are used in photogrammetry software to calculate the specific sensitivity of each pixel to compensate local as well as global variations in sensitivity. Sensitivity tables are calculated for each sensor and aperture setting, and applied during post processing from level 0 to level 1.
Outlier Pixels that do not have a linear behavior as described in the CCD specifications are marked as defective during the calibration procedure in photogrammetry. These pixels are not used or only partially used during post processing and the information is restored by interpolation between the neighborhood pixels surrounding the defective pixels. Certain pixels that are named Qmax pixels due to the fact that they can only store and transfer charge up to a certain maximum amount are detected in an additional calibration step. These pixels are treated differently during post processing in photogrammetry, since their behavior can affect not only single pixel values but whole columns.