American artist Cayce Zavaglia creates amazingly layered embroidered portraits that look more like paintings than thread work. From her website:
Initially, working with an established range of wool colors proved frustrating. Unlike painting, I was unable to mix the colors by hand. Progressively, I created a system of sewing the threads in a sequence that would ultimately give the allusion of a certain color or tone. The direction in which the threads were sewn had to mimic the way lines are layered in a drawing to give the allusion of depth, volume, and form. Over time the stitches have become tighter and more complex but ultimately more evocative of flesh, hair, and cloth.