What's the principle behind gender detection? Is it based on machine learning algorithms trained with a huge pile of data, or is there some inherent geometric difference between male and female faces that I'm missing?
There's definitely geometric differences between male and female faces. The most distinct difference is that the male chin tends to be larger, giving the face a more "square" shape, while female faces have smaller chins, giving the face a slight "almond" shape. And I'm sure there's more subtle differences as well.
