Lukáš Tůma, USGS already provides Surface Reflectance (SR) or BOA higher level Landsat products for free via the https://espa.cr.usgs.gov/. After you download the SR product, you can follow the Landsat product guide to scale the reflectance in the 0 to 1 range. For example, check the table on page 21 in the attached product guide of Landsat 8.

There is however, a temporary federal government shutdown in the US right now, due to which the website is down. Alternatively, if you are performing atmospheric correction manually, follow the instructions provided on ENVI's website. Depending on the atmospheric correction algorithm you use, ENVI has a set of instructions. For example, while using FLAASH, the input image needs to be in Radiance.

https://landsat.usgs.gov/landsat-science-data-products

https://www.harrisgeospatial.com/docs/FLAASH.html

Thank you very much. And only because of my curiosity, is it possible to correct TOA reflectance by atmospheric correction to BOA reflectance? Or atmospheric correction is only supposed for radiance...

Hi Lukas,

If you have access to ENVI software or IDL program, there are two built-in atmospheric correction algorithms (FLAASH and QUAC) with which you can convert from ToA to SR/BoA.

I'm not sure if you can convert from ToA to BoA, but with FLAASH/QUAC atmospheric algorithms applied, you can convert the raw radiance image to the SR/BoA image. If you need to compare ToA vs BoA, you can calculate both of these separately (BoA as I said before and ToA by simply implying a radiometric calibration with ENVI).

Thanks!