Using bitmap data to vary geometry in an array

I am trying to generate array of tiles where the 'cell complexity' of tiles differs according to data generated by a bitmap, so that from a distance you could see the pattern in the array of tiles. 

In current iteration I have used only two cell complexities but ideally would like the option for more, however I cannot figure out how to do this without description becoming unwieldy.

Description with annotation attached. 

 Nathan%20and%20Caitlin%20Tile_Resubmit_v9_Forum%20File.gh