The GBNDVI operator algorithm computes the Green-Blue Normalized Difference Vegetation Index from a given product.

The GBNDVI results from the following equation:

GBNDVI = (N - (G + B)) / (N + (G + B))

, where:

The bands are:

- B is the Blue band
- G is the Green band
- N is the NIR band

Also the processor computes an additional flags band called 'gbndvi_flags' with the following bit coding:

Bit Position	Description
Bit 0	The computed value for GBNDVI is NAN or is Infinite
Bit 1	The computed value for GBNDVI is less than -1 (minus one)
Bit 2	The computed value for GBNDVI is greater than 1 (one)