A Comparison of Relative Gain Estimation Methods for High Radiometric Resolution Pushbroom Sensors

Modern optical remote sensing satellite instruments are increasingly using a pushbroom design for the focal plane and are also incorporating greater radiometric resolution with 12 bits/pixel, or greater, becoming more common. Both of these design features demand that high precision methods be developed for estimating the relative gain differences among detectors on the focal plane. This paper reviews three approaches – onboard diffuser, side-slither, and lifetime statistics – and provides a direct comparison of their performance. All three methods of relative gain estimation, onboard diffuser, side slither, and lifetime statistics, are capable of excellent performance and can be used for high radiometric resolution optical sensors. For those sensors that have the luxury of an onboard diffuser, a diffuser-based approach can provide accurate relative gain estimates as often as needed by the sensor. Conversely, for those systems that cannot accommodate a diffuser panel, both the side slither and lifetime statistic methods work well. For those sensors that cannot perform a yaw maneuver, the lifetime statistics approach provides adequate results. Thus, a methods for estimation of relative gains is always available for any type of sensor capability.