Explain, strictly from within the framework of Darwinian evolution, how natural selection “crafted” such an organ

Consider the human eye, an exquisitely adapted organ that gives rise to stereo vision in full color (see, for instance, “The Evolution of Primate Color Vision” by Gerald H. Jacobs and Jeremy Nathans, Scientific American, April 2009 issue, pp. 56-63).
Explain, strictly from within the framework of Darwinian evolution, how natural selection “crafted” such an organ