What multigrid and Poisson do to one's image

htmlabstractThough the pun in the title is intended, it is not quite fair to Piet Wesseling as he is a person who promoted the development of multigrid to far more complicated equations than the Poisson equation. Instead, the title should be taken more literally as it truly relates to the contents of this note. It is shown that while multigrid is renowned for his efficiency in solving partial differential equations, integral equations and what not, it can also, maybe surprisingly, be used for the multiresolution of images.