Green Difference Vegetation Index
As you could assume from the name the Green Difference Vegetation Index is an index of greenness or photosynthetic activity of living plants. It is specifically sensitive to the variation of chlorophyll content in plants.
You can see below this algorithm is also very similar DVI with the substitution of Green instead of Red in the equation. Because of this change the GDVI is more sensitive to the concentration of chlorophyll in plants.
GDVI = NIR - Green
If a plant is taking in the right amount of water or nitrogen it becomes greener and healthier. These elements fuel the photosynthesis process through the production of chlorophyll. Because of this the GDVI algorithm is most commonly used to determine water and fertilizer uptake across a field. With good source data and GDVI results you will be able to allocate your water and fertilizer in a more effective way. Expected values will range from -255 to 255 in the output file.
Reference: Sripada, R., et al. "Aerial Color Infrared Photography for Determining Early In-season Nitrogen Requirements in Corn." Agronomy Journal 98 (2006): 968-977