  In approximation theory classical discrete operators, like generalized
sampling, Sz\'{a}sz-Mirak'jan, Baskakov and Bernstein operators, have been
extensively studied for scalar functions. In this paper, we look at the
approximation of curves by a class of discrete operators and we exhibit
graphical examples concerning several cases. The topic has useful implications
about the computer graphics and the image processing: we discuss applications
on the approximation and the reconstruction of curves in images.
