1. A stereoscopic image rendering system comprising: a receiver unit adapted to receive a pair of stereoscopic images; and an image processing unit adapted to compute a first depth map from the pair of stereoscopic images; determine extreme depth values from a window selected in the depth map; determine a filter map based on the extreme depth values; and compute a second depth map by combining the filter map with the first depth map; wherein the filter map is defined with a quadratic function expressed by the formulae αx2+βx+γ, wherein α, β and γ are parameters, the extreme depth values include a minimal depth value and a maximal depth value, the minimal depth value being assigned to the parameters α and γ, and the maximal depth value being assigned to the parameter β.