Why are some Landsat 4-5 TM browse so dark and low contrast?
Differences in the browse generation algorithms used to create the Landsat 7 ETM+ and the Landsat 4-5 TM browse result in the TM browse being sometimes significantly darker and lower contrast than similar scenes in the ETM+ inventory over the same geographic region. The differences in the browse generation algorithms have been identified and changes to the Landsat TM browse generation algorithm are scheduled. These changes will correct differences in the specifics of the method used to histogram the data before processing the contrast stretch, bringing the two algorithms closer together so the browse generated by each will be visually more similar in brightness and contrast. The changes to the Landsat TM browse generation algorithm are scheduled for release in early March, 2005, but that will only affect the new browse being created from that date forward. There currently is not a reprocessing plan to address the dark browse in the current TM inventory. Until the new algorithm is in pl
