  We investigate one-parameter deformations of functions on affine space which
define parameterizable hypersurfaces. With the assumption of isolated polar
activity at the origin, we are able to completely express the L\^{e} numbers of
the special fiber in terms of the L\^{e} numbers of the generic fiber and the
characteristic polar multiplicities of the comparison, a perverse sheaf
naturally associated to any reduced complex analytic space on which the
constant sheaf $\Q_X^\bullet[\dim X]$ is perverse. This generalizes the
classical formula for the Milnor number of a plane curve in terms of double
points as well as Mond's image Milnor number. We also recover results of
Gaffney and Bobadilla using this framework. We obtain similar deformation
formulas for maps from $\C^2$ to $\C^3$, and provide an ansatz for obtaining
deformation formulas for all dimensions within Mather's nice dimensions.
