This is a loom in Ghana used to weave Kente cloth. The 2 harnesses in front, with dark string heddles, are used to weave plain weave in the warp-striped sections. The other two in the back with white string heddles are used to weave the patterns sections that are weft-faced. The figure in the pattern sections is inlay, pick-up. One pair of harness is used in one part of the weaving then the other pair are used.Tien says:
The Ewe weaving I was taught used two pairs of shafts, one white pair which was used to weave pattern, threaded 1-1-1-1-2-2-2-2 (i.e. “plainweave” except with four threads in each heddle) with groups of four threads in each heddle, and one blue pair, which was threaded with single threads in a plainweave pattern. Each thread passed through both pairs of heddles. Given the threading and the sett (which I haven’t measured yet, but the thread we were using was roughly the weight of sewing thread), the plainweave sections came out as a balanced weave (equal parts warp and weft showing), while the pattern section, having 4 ends in each heddle, came out weft-faced, with no warp showing.
This photo and more about this type of weaving can be seen at Tien Chiu's blog, http://www.tienchiu.com/travels/ghana/kente-weaving-in-ghana/.