The PSRI operator algorithm computes the Plant Senescing Reflectance Index from a given product.

The PSRI results from the following equation:

PSRI = (R - B) / RE2

, where:

The bands are:

- B is the Blue band
- RE2 is the Red Edge 2 band
- R is the Red band

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

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