Landsat Missions
Question:
Why do some browse images have a color shift midway through the scene?
Answer:
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. When an order is placed, a calibration parameter file (CPF) containing all gain change information will be used to process the data, incorporating the appropriate gain and bias values into the scene processing. While this artifact will not exist in the final processed (Level 1) product, there may be a single residual scan line of altered Digital Number (DN) values in the affected band(s) at the location where the gain change occurred.
U.S. Department of the Interior |
U.S. Geological Survey
URL: http://landsat.usgs.gov
Page Contact Information: landsat@usgs.gov
Page Last Modified: November 24, 2009
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