[mapserver-users] Raster merge

[Andrew Mason]

Hello List,

I wonder if anyone can anyone suggest a possible mechanism for  
achieving the following?

I have two rasters covering the same area.

Raster A contains the suitability of the location for the growth of  
Species A (on a scale of 1 to 30)
Raster B contains the suitability of the location for the growth of  
Species B (on a scale of 1 to 30)

I would like to generate a layer that shows the result of the  
following rule:

Display green at locations where Species A suitability is > 18
Otherwise if Species B suitability > 14 display blue
Otherwise display red.

Thank you

Andrew Mason