Usually anisotropic filters are implemented as second order PDEs; see, for instance. The main drawback of these models is that they convert smooth functions into piecewise constant functions in a phenomenon known as the staircase effect, which causes images to look blocky. Although some effort has been made to numerically reduce the staircase effect in second order models , some researchers trying to avoid this problem have turned to higher order models. In this direction are, for instance, the works presented in [55, 36, 35, 56]. However, very few papers have touched on fast solvers for these high order models, and this work aims to partially fill this gap.