1. A method for estimating the intensity of a pixel included within an image, the method comprising: (i) generating a plurality of bidirectional paths extending between a light source and a set of measurement points, each bidirectional path comprising a light subpath extending from the light source and an eye subpath extending from the view point and coupled to the light subpath, wherein each light subpath is characterized by a number of vertices included within said light subpath, and wherein each eye subpath is characterized by a number of vertices included within said eye subpath; (ii) sorting the plurality of bidirectional paths into separation populations, wherein each population includes bidirectional paths constructed from eye subpaths having a common number of vertices, and light subpaths having a common number of vertices; (iii) computing an intensity contribution of each population, and (iv) summing the intensity contributions over a plurality of populations to estimate the intensity of the pixel.