greeness.md

Formula	What It Accounts for	Limitations	How to Use it	Misc.	Citation(s)
Green chromatic coordinate (Gcc) Gcc = G/(R+G+B)	Green pigmentation in vegetation	Different color leaves, background like soil	Take mean of green pixels (digital numbers) for each ROI and then apply Gcc data transformation	Calculate the 90th percentile method* to minimize variation between different illuminations	Woebbecke, D.M et. al, 1995; Gillespie A., et al, 1987
Excess greenness index (ExG) ExG = 2G-(R+B)	Minimize variation between different illuminations (light quality) and enhance detection of plants	Can’t compare absolute values of different cameras	Calculate average of digital numbers across ROI and then apply data transformation	Named ‘2G_RBi’ in Richardson 2007	Sonnentag, O. et. al, 2012
Green Leaf Index (GLI) GLI = (2×G-R-B)/ (2×G+R+B)
CIVE = 0.441R-0.811G+0.385B+18.78745	Can measure crop growth status				Kataoka et. al, 2003
Normalized difference index (NDI) NDI = 128×((G-R)/(G+R))+1					Perez et al., 2000 (links to original paper although equation was slightly modified)
Excess Red ExR = 1.3R-G	Illumination issues that make it difficult to tease apart redness from crops/leaves from soil or camera artifacts				Meyer et al., 1998 (links to closely related paper)
ExGR = ExG-ExR	Minimize variation between different illuminations				Neto et. al, 2004
Combined Indices 1 = ExG + CIVE					Guijarro et al., 2011
Combined Indices 2 = 0.36ExG + 0.47CIVE + 0.17VEG					Guerrerro et al., 2012
Normalized Green-Red Difference (NGRDI) NGRDI = g-r/g+r	Can measure crop growth status				Hunt et. al, 2005
Vegetative Index (VEG) VEG = g/(rab1-a); a = 0.667	Minimize illumination differences between images				Hague et al., 2006
% Green = G/(R+G+B)					Richardson et al 2007