We study the Perspective Shape from Shading problem from the numerical point of view pre-
senting a simple algorithm to compute its solution. The scheme is based on a semi-Lagrangian
approximation of the first order Hamilton-Jacobi equation related to the problem. The scheme is
converging to the weak solution (in the viscosity sense) of the equation and allows to compute
accurately regular as well as non regular solutions. Since the partial differential equation must be
complemented with boundary conditions on the silhouette, we analyse the effect of various types
of boundary conditions on the numerical solution. Some tests on synthetic and real images are
presented.
