gdal - How to produce a mean raster file based on other raster files?

Possible Duplicate:
Tools to flatten the jp2 to a single band (average the bands)?

I have a number of raster files from a same area, that coordinates of corresponding pixels perfectly match one another. I have to perform simple operations like producing a raster that its pixel values are the average of a 3 raster files corresponding pixel values. Simply speaking, I want a new raster file that is average of 3 other raster files.

Answer

Have a look at gdal_calc.py. You'll probably find some useful examples here