“…Vegetation indices can be derived from RGB color space indices, which represent international standards for color perception by the human eye and were adopted by the Commission Internationale de l'Eclairage (CIE) in 1976 (Yam and Papadakis, 2004;Trussell et al, 2005;Casadesús et al, 2007;Liu et al, 2011;Kipp et al, 2014;Zhou et al, 2015). Several studies show that RGB color space indices, such as hue, a * , u * , and other derived indices, such as green area (GA) and the normalized difference CIELab index (NDlab), outperformed spectral indices such as NGRDI, NDVI, and gNDVI, in predicting yield of wheat and maize more accurately and had higher broad sense heritability for drought tolerance in forage grasses (Kefauver et al, 2015;Vergara-Díaz et al, 2015Zhou et al, 2015;Gracia-Romero et al, 2017Buchaillot et al, 2018Buchaillot et al, , 2019Fernandez-Gallego et al, 2019;De Swaef et al, 2021).…”