CI Algorithm Specification |

### CI

The Colour Index algorithm was developed to differentiate soils in the field - Pouget et al.(1990).
Low valued CIs have been shown to be correlated with the presence of a high concentration of carbonates or sulfates and higher values to be correlated with crusted soils and sands in arid regions (Escadfal, 1989).
In most cases the CI gives complementary information with the BI and the NDVI. Used for diachronic analyses, they help for a better understanding of the evolution of soil surfaces

The CI results from the following equation:

CI = (red_factor * red - green_factor * green) / (red_factor * red + green_factor * green)

### CI-Flags

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

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