Essentially, they trained a computer to determine, for each individual face, the most attractive set of distances and then choose the ideal closest to the original face. Unlike other research with formulas for facial attractiveness, this program does not produce one ideal for a feature, say a certain eye width or chin length.

They ran the photographs of 92 women and 33 men through the engine, creating before and after shots  essentially, a computer-generated version of hot or not. Changes were made only to the geometry of the faces; unlike the digital retouching done for fashion magazines, wrinkles were not smoothed and hair color was not changed.

The research, published in the August proceedings of Siggraph, an annual conference on computer graphics, is one of the latest studies in a growing field that merges beauty and science, a subject that has drawn mounting interest in academia in the last decade.

Studies have shown that there is surprising agreement about what makes a face attractive. Symmetry is at the core, along with youthfulness; clarity or smoothness of skin; and vivid color, say, in the eyes and hair. There is little dissent among people of different cultures, ethnicities, races, ages and gender.

Yet, like the many other attempts to use objective principles or even mathematical formulas to define beauty, this software program raises what psychologists, philosophers and feminists say are complex, even disturbing, questions about the perception of beauty and a beauty ideal.