Ben Spencer and Mark W. Jones have again won the Computer Graphics Forum cover competition. The winning image will be used throughout 2013 as the front cover image of the journal Computer Graphics Forum. The image shows a visualisation of the parameter space of photon trajectory from the emitting light source. When encoded into the photon map, this can be used to distinguish overlapping light envelopes typically associated with caustics. This enables more accurate density estimation along overlapping illumination, thus producing more accurate renders. The technique is described in an upcoming Eurographics 2013 paper. See their previous prize winning entry for 2009.