thank you very much.
it seems to work nicely : i can set a color to a cube by specifying its coords (X,Y in pixels frop a TOP) in a CHOP.
the main problem is now to, somehow, generate it.
Let's say I have a 40*40 pixels image that i need to map on cubes, i can't just copy/paste this 1600 times and change the X,Y values.
Any ideas ?