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).
This will be visible in the browse images because these are created using raw uncalibrated data, but should not exist in the Level 1 processed 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 however).
A calibration parameter file (CPF) containing gain change information is used during processing to incorporate the appropriate gain and bias values.
U.S. Department of the Interior |
U.S. Geological Survey
URL: http://landsat.usgs.gov
Page Contact Information: Ask Landsat
Page Last Modified: 03/7/11 12:55 pm
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