CIred-edge takes advantage of a narrow spectral band between the red and the near-infrared (NIR) bands of the plant reflectance range. The red-edge band is highly sensitive to the light reflected off of the cellular structure of a plant. Brighter reflectance corresponds to a larger number of plant cells and, by extrapolation, to the greener area.

Sentinel = (B08/B06)-1
Firefly = (B118/B080)-1