Red Edge Inflection Point (REIP) identifies the precise wavelength where the transition from red absorption to near-infrared reflectance occurs — this inflection point is strongly correlated with chlorophyll content, nitrogen status, and overall plant health. REIP is valuable for assessing crop vigor, nitrogen uptake, leaf area index (LAI), and biomass. It is particularly effective for precision agriculture and nutrient management.

Firefly = 700+ 40 * ((B062 + B095)/2 - B071) / (B082 - B071)
Sentinel 8-9 = 705 + 35 * ((B04 + B07)/2 - B05) / (B06 - B05)