By sampling only localized land imagery the claimed method computes {HEAD ~ black points} that are more robust against {TAIL ~ the localized effects} of atmospheric and land reflection effects than black points computed from wider areas 
are robust against
By sampling only localized land imagery the claimed method computes { HEAD ~ black points } that are more robust against { TAIL ~ the localized effects } of atmospheric and land reflection effects than black points computed from wider areas
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH REL OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH