Minimize Smile Correction
The purpose of smile correction is to correct TOA reflectance (gaseous absorption has already been corrected in a previous processing step) for small-scale variations due to the non-constant central wavelength of a given band across the field of view. Correction is only made for a programmable subset of bands, for which variations can induce severe distortions, after corrections based on a fixed wavelength scheme (e.g. Rayleigh scattering correction). This subset of bands, specific to land and water surface types, ensures smoothness in reflectance local variations with wavelength and allows an accurate estimation of the reflectance derivative using neighbouring bands.
Functional Block Diagram of Smile Correction