Hello I am trying to convert the DN values of Landat 8 OLI to surface reflectance, I did the atmospheric correction with flaash module using ENVI 5.1, and also the new filter function landsat8_oli.sli from the \envi51\resource\filterfuncs directory. would you please tell me, how can I calculate the surface reflectance values between 0 and 1?????????? the result of atmospheric correction is just digital numbers, the maximum value in my study area is approximately 5000 so when I try to use the usgs formula to retrieve TOA reflectance all the values are negative for most of the bands. for example I have values between 0 and 2046 for green band (atmospherically corrected), using USGS TOA reflectance conversion formula ρλ' = MρQcal + Aρ the values of green band (blue band etc) (2046* 2.0000E-05) - 0.100000 are always negative. Thank you in advance for your feedback