  We show that if (u;K) is a minimizer of the Mumford-Shah functional in an
open set of R^3, and if x, K and r > 0 are such that K is close enough to a
minimal cone of type P (a plane), Y (three half planes meeting with 120 degrees
angles) or T (cone over a regular tetrahedron centered at the origin) in terms
of Hausdorff distance in B(x; r), then K is C^1,alpha equivalent to the minimal
cone in B(x; cr) where c < 1 is an universal constant.
