A ccurately re-creating a three-dimensional face from the subtle shading in a photo- graph has long challenged computer scientists. Their algorithms, it now seems, were too gener- al—aspiring to describe the moon’s surface as well, or rather as poorly, as the human head. But by recognizing the fact that head shapes are as- tonishingly regular, Joseph J. Atick, Paul A. Grif- fin and A. Norman Redlich of the Rockefeller University have found a quick means of repro- ducing the unique contours of a person’s face from a snapshot. The discovery may revolutionize the treat- ment of burn victims. Clear plastic masks, fitted over a patient’s face to control the formation of scar tissue, end up determining his or her ap- pearance. Currently the masks are made by tak- ing a painful plaster cast of the burnt face. The Rockefeller technique will instead allow the masks to be constructed from a photograph tak- en prior to the burn, by generating the three-di- mensional face. Scientists at the Computerized Anthropometric Research and Design (CARD) Laboratory at the Wright-Patterson Air Force Base are working to develop such masks. The insight that led to this breakthrough may be even more informative. “Any human face is a combination of a few dozen primary shapes,” Atick maintains. The researchers analyzed 347 three-dimensional scans of heads of air force pi- lots—mostly white men—taken at the CARD lab. From 200 of these, they derived an average, adult white male head shape—dubbed the meanhead (top row, far left )—and a set of 200 standardized variations from that shape, the eigenheads (15 of which are shown in consecutive rows). The latter are so called because they are eigenfunctions, solutions to a set of linear equations that offer the most economical way to store information. The eigenheads thus vastly simplify the derivation of a full face from the shading in a picture, a problem that would otherwise involve an in- finite number of variables. Each of the remaining 147 heads in the database was reproduced to within 1 percent by com- bining the meanhead with no more than 40 eigenheads. The eigenheads may be more than a mathematical aid. The inferior temporal cortex has “face cells,” neurons that fire selectively when a human visage is presented. Why certain cells respond to a given face is not known. But brains have a penchant for eigenfunctions: color, for ex- ample, is analyzed via the blends of red, green and blue that form eigencolors. Our brains may also have figured out that head shapes are best coded as eigenheads. “Each cell might fire in response to a particular eigenhead,” Atick suggests—giving humans their incredible capacity to rec- ognize individual faces. —Madhusree Mukerjee

Here's the article. if someone can get past the paywall, godspeed.