I'm learning how to perform atmospheric correction manually, hence not using the automated methods available in ENVI
metadata (band 1) for my Landsat 8 scene is as follows;
RADIANCE_MULT_BAND_1 = 1.2344E-02
RADIANCE_ADD_BAND_1 = -61.72016
REFLECTANCE_MULT_BAND_1 = 2.0000E-05
REFLECTANCE_ADD_BAND_1 = -0.100000
SUN_ELEVATION = 48.12237303
So when I use band math to calculate TOA Radiance I type in this:
When I use any of the following band math formulae;
TOA Reflectance (excluding sun elevation adjustment)
TOA Reflectance (including sun elevation adjustment)
Or calculate straight from the raw DN to TOA Reflectance (including sun elevation adjustment)
I end up with something like this:
which looks incorrect.
I've googled and either my search terms are rubbish or no one uses manual band math to do this.
Mikkel's answer below with the revised band math calculation (omitting the intermediate steps) yielded the following statistics:
which look somewhat more realistic.
Wondering if i should add 13.4305 to each band, or ignore the negative minimum?
Mikkel was spot on again, in suggesting that the -13.4305 values were isolated to the "no data" areas around the image;
as you can see, isolated only to the northern edge of the scene.
[END EDIT #2]