Vegetation has a unique spectral signature that enables it to be distinguished readily from other
types of land cover in an optical/near-infrared image. The reflectance is low in both the blue and
red regions of the spectrum, due to absorption by chlorophyll for photosynthesis. It has a peak at
the green region. In the near infrared (NIR) region, the reflectance is much higher than that in
the visible band due to the cellular structure in the leaves. Hence, vegetation can be identified by
the high NIR but generally low visible reflectance. This property has been used in early
reconnaissance missions during war times for "camouflage detection".