(n) the process of producing pictures in contrasting colors that appear three-dimensional when superimposed and viewed through spectacles with one red and one green lens
n. [ Gr. &unr_; wrought in low relief, &unr_; embossed work; &unr_; + &unr_; to engrave. ] Any sculptured, chased, or embossed ornament worked in low relief, as a cameo. [ 1913 Webster ]