Normalized Difference Red Edge Index

The normalized difference red edge index (NDRE) is a metric that can be used to analyse whether images obtained from multi-spectral image sensors contain healthy vegetation or not.^[1] It does this by measuring the amount of chlorophyll in a plant.^[2]

It is similar to Normalized Difference Vegetation Index (NDVI) but uses the ratio of Near-Infrared and the edge of Red as follows:^[3]

${\displaystyle {\mbox{NDRE}}={\frac {({\mbox{NIR}}-{\mbox{RE}})}{({\mbox{NIR}}+{\mbox{RE}})}}}$

The red edge is the part of the spectrum centered around 715 nm.

The Index will give a value between -1.0 to +1.0, with a higher value showing a healthy plant environment.^[3]