I don't know about overlay redux, but in my opinion it's not hard to loop through all pixels really... It might just be pretty slow as mmf is. What are you using the average for btw?
I would like to destroy the terrain and then destroyed area shoots some rocks and they are the same color of the terrain.
However it would be very nice to se color from a X and Y position where I destroyed terrain, but that sets the color to all of the rocks. So if I destroy area in many different positions, the rocks color will bug