{HEAD ~ This spectral reflectance} can be also measured using a spectrophotometer or {TAIL ~ a spectral reflectometer}, or may be measured using the densitometer for measuring the optical density as a logarithm of the spectral reflectance 
measured using
{ HEAD ~ This spectral reflectance } can be also measured using a spectrophotometer or { TAIL ~ a spectral reflectometer } , or may be measured using the densitometer for measuring the optical density as a logarithm of the spectral reflectance
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH REL REL OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH