Spectral envelope refers to the edges of the spectral properties of a feature, expressed as the range of brightness in the electromagnetic spectrum, as measured by a spectrometer.
... racial makeup of the town is 46.37% White, 44.23% African American, 0.85% Native American, 0.85% Asian, 0.00% Pacific Islander, 2.35% from other races, and 5.34% from two ...