The ExR operator algorithm computes the Excess Red Index from a given product.

The ExR results from the following equation:

ExR = 1.3 * R - G

, where:

The bands are:

- G is the Green band
- R is the Red band

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

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