A novel method to analyze and to distinguish the non-dissipative component from the dissipative frictional component of the lateral force in a Scanning Force and Friction Microscope (SFFM) is worked out and applied to images acquired on various samples. We have determined the twisting spring constants of the cantilevers by computer statical analysis, since they are essential for the quantitative determination but are not provided by the manufacturer. Quantitative results for the μ D dynamical friction coefficient images are reported. Comparison with the forward-backward lateral force image subtraction model is made.