1. A method of calibrating a system for extracting a surface profile from a stereo pair of images obtained at an arbitrary setting S of an optical system, comprising: determining surface profile reconstruction parameters for a stereo pair of images obtained with the optical system at a reference setting S0 of the optical system, the reference setting S0 being different from the arbitrary setting S; determining warping parameters for a digital image processor for warping the stereo pair of images obtained with the optical system at the arbitrary setting S into a stereo pair of warped images corresponding to the reference setting S0; wherein the settings S and S0 include at least a different configuration for magnification of the optical system; and further comprising recording surface profile reconstruction parameters for a plurality of reference settings in a table.