Dark Subtract adds value to landsat bands 5 and 7 instead of

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Last Post 26 Aug 2011 10:14 AM by anon

Dark Subtract adds value to landsat bands 5 and 7 instead of subtracting

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anon

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26 Aug 2011 10:14 AM
Hi Everyone, i'm using ENVI 4.8 to process Landsat 5 tm and landsat 7etm images. After the automatic dark subtract process, i noticed that the reflectance values for band 5 and band 7 are actually higher then the original. Have any1 experienced this before?? does anyone knows why this is happening?? Many Thanks in Advance.

MariM

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26 Aug 2011 12:17 PM
Did you calibrate the data to radiance first? Did you use the band minimum or user value?

Deleted User

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27 Aug 2011 12:28 AM
Data was calibrated to at-sensor reflectance and i used band minimum.

Deleted User

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28 Aug 2011 09:34 AM
i figured it out. turns out my images have negative band values due to the calibration. i'll dark-subtract with user inputs.

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