We consider the problem of constructing the depth image of a heterogeneous model (f.ex. the subsurface) based on surface measurements. Due to a limited-aperture and band limited signals, the output from a general inversion scheme will be a distorted or blurred image. If the transmitter/receiver layout, the signal bandwidth and the (initial) background model are all known, this distortion can be computed employing the concept of resolution functions. For a general heterogeneous model this function will be space-variant. Hence, knowing the resolution function such image distortions can in principle be corrected for.