**Figure 4:** Error in estimating the displacement of
a particle location from the digitizing grid as a function of
the size *w* of the mask used for centroid refinement.
Heavy lines are quadrature sums of the error estimates in
eqns. (12) and (13).
Circles are Monte-Carlo calculations for Gaussian surfaces of
revolution with additive noise and
halfwidths *s* = 6 pixels (a) and *s* = 2 pixels (b).
In both cases, the error estimate provides an adequate
value for both the optimal kernel support, *w*, and for the
accuracy of the position estimate at that value.

Mon Mar 11 23:01:27 CST 1996