The authors present the results of a statistical analysis of the penumbra of sunspots. The intensity distribution, and several parameters derived from it, is analysed at different heliocentric angles and positions on the spot. It has revealed, on the one hand, that a two-component model is compatible with the observations and that both components lie at the same height, and on the other, that the penumbral asymmetry found by Collados et al. (1987) is confirmed under a photometrical point of view, the western penumbra being slightly shorter than the eastern one.