Abstract: We present a powerful technique to simulate and approximate caustics in images. Our algorithm is designed to produce good results without the need to painstakingly paint over pixels. The ability to edit global illumination through image processing allows interaction with images at a level which has not yet been demonstrated, and significantly augments and extends current image-based material editing approaches. We show by means of a set of psychophysical experiments that the resulting imagery is visually plausible and on par with photon mapping, albeit without the need for handmodeling the underlying geometry.