### BI2

The **second** **B**rightness **I**ndex
algorithm is representing the average of the brightness of a
satellite image.

The result looks like a panchromatic image with the same
resolution of the original image.

This index is therefore sensitive to the brightness of soils which
is highly correlated with the humidity and the presence of salts in
surface (Escadafal, 1989).

The BI2 results from the following equation:

**BI2 = sqrt( ( (red_factor * red * red_factor * red) +
(green_factor * green * green_factor * green) + (IR_factor *
near_IR * IR_factor * near_IR) ) / 3 )**

### BI2-Flags

Also the processor computes an additional flags band called
'bi2_flags' with the following bit coding:

Bit Position |
Description |

Bit 0 |
The computed value for BI2 is NAN or is Infinite |

Bit 1 |
The computed value for BI2 is less than 0 (zero) |

Bit 2 |
The computed value for BI2 is greater than Floating Point
Maximum Value |