The Vitruvian Man, is a drawing by Leonardo da Vinci around 1490. It is accompanied by notes based on the work of the architect Vitruvius. The drawing, which is in pen and ink on paper, depicts a man in two superimposed positions with his arms and legs apart and inscribed in a circle and square.

The drawing is based on the correlations of ideal human proportions with geometry described by the ancient Roman architect Vitruvius in Book III of his treatise De Architectura.

Source: Wikipedia, Vitruvian Man

Selective color is a post-processing technique where most of a photo is converted to black and white, but some parts are left in color.