5.1 Detector Response Calibration

As we have discussed before, Landsat MSS has 6 detectors at each band, TM has 16 and SPOT HRVs have 3000 or 6000 detectors. The differences between the SPOT sensors and Landsat sensors are that each SPOT detector collects one column of an image while each detector of Landsat sensors corresponds to many lines of an image (Figure 5.1).

Figure 5.1. Images acquired using detectors in linear array sensors and in scanners

The problem is that no detector functions the same way as others. If the problem becomes serious, we will observe banding or striping on the image.

There are two types of approach to overcome the detector response problems: absolute calibration and relative calibration.

5.1.1 Absolute calibration

5.1.2 Relative calibration