SURF has later been shown to have similar performance to SIFT, while at the same time being much faster. Other studies conclude that when speed is not critical, SIFT outperforms SURF. Specifically, disregarding discretization effects the pure image descriptor in SIFT is significantly better than the pure image descriptor in SURF, whereas the scale-space extrema of the determinant of the Hessian underlying the pure interest point detector in SURF constitute significantly better interest points compared to the scale-space extrema of the Laplacian to which the interest point detector in SIFT constitutes a numerical approximation.