Why do some Landsat 7 (ETM+) browse images appear to be split midway through a scene?
A linear shift in color is due to gain change in the sensor, which occurs when the sensor encounters an area of consistently different reflectance (for example, when the sensor encounters snowy regions or highly reflective desert areas). These artifacts will be apparent in the Landsat 7 browse, because the browse image has been generated directly from raw uncalibrated data. However, when the Landsat 7 order is placed, a calibration parameter file containing all gain change information will be used to process the data. Therefore, the appropriate gain and bias values will be incorporated into the scene processing. These artifacts will not exist in the final processed (Level 1) product.
