Syntax: thm.themis_emissivity(rad=VAL[, bandlist=INT][, ignore=VAL][, temp_rad_path=STRING][, b1=INT][, b2=INT][, max_emiss=FLOAT])
'rad' - any 3-D radiance array.
'bandlist' - an ordered list of THEMIS bands in rad. Default is 1:10.
'ignore' - non-data pixel value. Default is -32768 AND 0.
'temp_rad_path' - alternate path to temp_rad lookup table. Default is /themis/calib/temp_rad_v4.
'b1' - first band to search for maximum brightness temperature. Default is 3.
'b2' - last band to search for maximum brightness temperature. Default is 9.
'max_emiss' - optional flag to designate the maximum allowable emissivity when searching for maximum brightness temperature.
thm.themis_emissivity() uses a lookup table to convert radiance in all bands to brightness-temperature. The maximum brightness temperature in bands 'b1' - 'b2' is used as the temperature of the surface. This temperature is used to calculate a blackbody radiance. Finally, the emissivity is the ratio of the measured radiance to the blackbody radiance.
This process is reversed using thm.emiss2rad.