average a texture map to vertex map

[Gerbrand Nel]

Hey guys.
I have to camera project footage onto a low poly object, and then average
all the colors per polygon to set the color of each polygon.
I thought of using particles colored by the emitters texturemap, but I cant
figure out how to average the colors per polygon, and then set it to the
vertex color.
As always I need to solve this problem yesterday, so any help would be
awesome.
Thanks smart people!
G