There is no agreed upon number of spectra that constitutes hyperspectral versus multispectral imagery. Typically, multispectral imagery consists of a handful of spectra, perhaps a dozen or fewer. Hyperspectral imagery often times consists of hundreds of spectra. For example, ProVision s current hyperspectral imaging system can capture up to 1024 spectra. Spectra are measurements of reflected energy.
All objects reflect a certain amount of electromagnetic energy.
The intensity of this reflected energy can be measured at various wavelengths. Many objects and substances have spectral characteristics that are unique. In many cases, the whole is greater than the sum of the parts. With hyperspectral imagery, reflected energy is measured in very precise wavelengths and at very small increments. In this way, subtle spectral features associated with various objects and substances are recorded that might go unnoticed in broad band multispectral imagery.