It is proved that local moments are related to their surface fitting c
oefficients by a linear transform, and by this the surface-fitting-bas
ed-feature extraction is converted into the computation of 2D local mo
ments. A NPT recursive method is proposed to compute 2D local moments
quickly and then to efficiently implement surface fitting. The new met
hod has a novel advantage that its computational complexity for both 2
D local moment computation and surface fitting is independent of the m
ask size, which much efficiently speed up the feature extraction.