// Soil Adjusted Vegetation Index (abbrv. SAVI)// General formula: (800nm - 670nm) / (800nm + 670nm + L) * (1 + L)// URL https://www.indexdatabase.de/db/si-single.php?sensor_id=96&rsindex_id=87// Initialize parametersletL=0.428;// L = soil brightness correction factor could range from (0 -1)letindex=(B08-B04)/(B08+B04+L)*(1.0+L);// calculate savi index// using colorblend visualization in EO browser returncolorBlend// Start of colorBlend function(index,// specify the index[0,0.1,0.2,0.4,0.5,0.7,1],// specify the borders[[0.69,0.88,0.90],// specify RGB colors [0.74,0.72,0.42],[0.60,0.80,0.20],[0.13,0.54,0.13],[0,0.50,0],[0,0.39,0],[0,0.29,0],]);/*
//using if statements visualization in EO Browser
if (index <-1) return [1,1,1]; // white color for values less than -1
else if (index <0) return [0.69,0.88,0.901]; // blue color majorly water
else if (index <0.09) return [0.74,0.72,0.42];
else if (index <0.1) return [0.64,0.8,0.35];
else if (index <0.2) return [0.57,0.75,0.32];
else if (index <0.3) return [0.60,0.80,0.19];
else if (index <0.4) return [0.13,0.63,0.13];
else if (index <0.5) return [0.13,0.55,0.13];
else if (index <0.6) return [0,0.50,0];
else if (index <0.7) return [0,0.39,0];
else if (index <1) return [0, 0.29,0];
else return [0,0,0];
*/
Empirically derived NDVI products have been shown to be unstable, varying with soil colour, soil moisture, and saturation effects from high density vegetation. In an attempt to improve NDVI, Huete [1] developed a vegetation index that accounted for the differential red and near-infrared extinction through the vegetation canopy. The index is a transformation technique that minimizes soil brightness influences from spectral vegetation indices involving red and near-infrared (NIR) wavelengths.
Description of representative images
SAVI visualized image, Italy. Acquired on 25.05.2020, processed by Sentinel Hub.