First let me tell you that this quilt is HUGE! Easily 7 feet across and 7 feet high. Second it is made completely of yo-yos!! Yo-yos are little ( these are probably about 2" diameter ) circles of cloth that a gathering stitch is sewn around the edge and pulled up. Kinda like a flattened pouch.
This entire image is made of different color yo-yos but, I think I know how they accomplished such dramatic effects... they turned the image into pixels and created and assembled yo-yos in the same colors and composition.
Regardless of how it was accomplished the size and execution is truly impressive.