1. A method comprising: obtaining a first spherical graph signal defined on a graph, the graph including a plurality of graph vertices and a plurality of graph edges, the first spherical graph signal including a plurality of spherical signal points, each spherical signal point being a point in a N-dimensional sphere of a given radius, each spherical signal point corresponding to one of the graph vertices; applying a spherical graph signal smoothing algorithm to the first spherical graph signal to produce a smoothed spherical graph signal defined on the graph, the smoothed spherical graph signal including a plurality of smoothed spherical signal points, each smoothed spherical signal point being a point in the N-dimensional sphere, each of the smoothed spherical signal points corresponding to one of the graph vertices; and replacing the first spherical graph signal with the smoothed spherical graph signal.